[libcamera-devel,v3,3/8] libcamera: v4l2_device: Add support for META_CAPTURE devices

Message ID 20190226162641.12116-4-jacopo@jmondi.org
State Superseded
Headers show
Series
  • v4l2_(sub)dev: improvements and tests
Related show

Commit Message

Jacopo Mondi Feb. 26, 2019, 4:26 p.m. UTC
Add support for devices that provide video meta-data to v4l2_device.cpp
and re-arrange bufferType handling in open() method.

Signed-off-by: Jacopo Mondi <jacopo@jmondi.org>
---
 src/libcamera/include/v4l2_device.h |  4 +++
 src/libcamera/v4l2_device.cpp       | 38 +++++++++++++++++------------
 2 files changed, 27 insertions(+), 15 deletions(-)

Comments

Kieran Bingham Feb. 26, 2019, 11:24 p.m. UTC | #1
Hi Jacopo,

On 26/02/2019 16:26, Jacopo Mondi wrote:
> Add support for devices that provide video meta-data to v4l2_device.cpp
> and re-arrange bufferType handling in open() method.
> 
> Signed-off-by: Jacopo Mondi <jacopo@jmondi.org>
> ---
>  src/libcamera/include/v4l2_device.h |  4 +++
>  src/libcamera/v4l2_device.cpp       | 38 +++++++++++++++++------------
>  2 files changed, 27 insertions(+), 15 deletions(-)
> 
> diff --git a/src/libcamera/include/v4l2_device.h b/src/libcamera/include/v4l2_device.h
> index 1d31d1b403bc..52eb6785cc15 100644
> --- a/src/libcamera/include/v4l2_device.h
> +++ b/src/libcamera/include/v4l2_device.h
> @@ -53,6 +53,10 @@ struct V4L2Capability final : v4l2_capability {
>  		return device_caps() & (V4L2_CAP_VIDEO_CAPTURE |
>  					V4L2_CAP_VIDEO_CAPTURE_MPLANE);
>  	}
> +	bool isMeta() const
> +	{
> +		return device_caps() & V4L2_CAP_META_CAPTURE;
> +	}
>  	bool isOutput() const
>  	{
>  		return device_caps() & (V4L2_CAP_VIDEO_OUTPUT |
> diff --git a/src/libcamera/v4l2_device.cpp b/src/libcamera/v4l2_device.cpp
> index 24e115554a99..8be8af7a2893 100644
> --- a/src/libcamera/v4l2_device.cpp
> +++ b/src/libcamera/v4l2_device.cpp
> @@ -79,6 +79,15 @@ LOG_DEFINE_CATEGORY(V4L2)
>   * \return True if the device can output video frames
>   */
>  
> +/**
> + * \fn bool V4L2Capability::isMeta()
> + * \brief Identify if the device is capable of providing video meta-data
> + *
> + * FIXME: add support for META_OUTPUT, introduced in Linux v4.20

I think I saw Niklas suggest to make this a Todo: rather than fixme -
but I don't think we need to worry too much over terminology that should
be removed within a couple of weeks :D as We'll update this after the
5.0 is released.


Likewise, I think the conditionals below might get some more thought put
into them when we add in META_OUTPUT - but that's all future work.

This patch gets us closer.

Reviewed-by: Kieran Bingham <kieran.bingham@ideasonboard.com>


> + *
> + * \return True if the device can provide video meta-data
> + */
> +
>  /**
>   * \fn bool V4L2Capability::hasStreaming()
>   * \brief Determine if the device can perform Streaming I/O
> @@ -280,33 +289,32 @@ int V4L2Device::open()
>  		<< "Opened device " << caps_.bus_info() << ": "
>  		<< caps_.driver() << ": " << caps_.card();
>  
> -	if (!caps_.isCapture() && !caps_.isOutput()) {
> -		LOG(V4L2, Debug) << "Device is not a supported type";
> -		return -EINVAL;
> -	}
> -
>  	if (!caps_.hasStreaming()) {
>  		LOG(V4L2, Error) << "Device does not support streaming I/O";
>  		return -EINVAL;
>  	}
>  
> -	if (caps_.isCapture())
> +	/*
> +	 * Set buffer type and wait for read notifications on CAPTURE devices
> +	 * (POLLIN), and write notifications for OUTPUT devices (POLLOUT).
> +	 */
> +	if (caps_.isCapture()) {
> +		fdEvent_ = new EventNotifier(fd_, EventNotifier::Read);
>  		bufferType_ = caps_.isMultiplanar()
>  			    ? V4L2_BUF_TYPE_VIDEO_CAPTURE_MPLANE
>  			    : V4L2_BUF_TYPE_VIDEO_CAPTURE;
> -	else
> +	} else if (caps_.isOutput()) {
> +		fdEvent_ = new EventNotifier(fd_, EventNotifier::Write);
>  		bufferType_ = caps_.isMultiplanar()
>  			    ? V4L2_BUF_TYPE_VIDEO_OUTPUT_MPLANE
>  			    : V4L2_BUF_TYPE_VIDEO_OUTPUT;
> -
> -	/*
> -	 *  We wait for Read notifications on CAPTURE devices (POLLIN), and
> -	 *  Write notifications for OUTPUT devices (POLLOUT).
> -	 */
> -	if (caps_.isCapture())
> +	} else if (caps_.isMeta()) {
>  		fdEvent_ = new EventNotifier(fd_, EventNotifier::Read);
> -	else
> -		fdEvent_ = new EventNotifier(fd_, EventNotifier::Write);
> +		bufferType_ = V4L2_BUF_TYPE_META_CAPTURE;
> +	} else {
> +		LOG(V4L2, Debug) << "Device is not a supported type";
> +		return -EINVAL;
> +	}
>  
>  	fdEvent_->activated.connect(this, &V4L2Device::bufferAvailable);
>  	fdEvent_->setEnabled(false);
>
Kieran Bingham Feb. 26, 2019, 11:28 p.m. UTC | #2
On 26/02/2019 23:24, Kieran Bingham wrote:
> Hi Jacopo,
> 
> On 26/02/2019 16:26, Jacopo Mondi wrote:
>> Add support for devices that provide video meta-data to v4l2_device.cpp
>> and re-arrange bufferType handling in open() method.
>>
>> Signed-off-by: Jacopo Mondi <jacopo@jmondi.org>
>> ---
>>  src/libcamera/include/v4l2_device.h |  4 +++
>>  src/libcamera/v4l2_device.cpp       | 38 +++++++++++++++++------------
>>  2 files changed, 27 insertions(+), 15 deletions(-)
>>
>> diff --git a/src/libcamera/include/v4l2_device.h b/src/libcamera/include/v4l2_device.h
>> index 1d31d1b403bc..52eb6785cc15 100644
>> --- a/src/libcamera/include/v4l2_device.h
>> +++ b/src/libcamera/include/v4l2_device.h
>> @@ -53,6 +53,10 @@ struct V4L2Capability final : v4l2_capability {
>>  		return device_caps() & (V4L2_CAP_VIDEO_CAPTURE |
>>  					V4L2_CAP_VIDEO_CAPTURE_MPLANE);
>>  	}
>> +	bool isMeta() const

One last thought here,

I'm a bit concerned that if we have isMeta and isOutput handling this -
we might end up with an ugly 2 x 2 matrix in if statements.

Any pretty way to make this better?

Or would it be cleaner to move towards:

bool isMetaCapture()
bool isMetaOutput()

This bit feels like a pain point - but I don't think that should stop
this patch right now.




>> +	{
>> +		return device_caps() & V4L2_CAP_META_CAPTURE;
>> +	}
>>  	bool isOutput() const
>>  	{
>>  		return device_caps() & (V4L2_CAP_VIDEO_OUTPUT |
>> diff --git a/src/libcamera/v4l2_device.cpp b/src/libcamera/v4l2_device.cpp
>> index 24e115554a99..8be8af7a2893 100644
>> --- a/src/libcamera/v4l2_device.cpp
>> +++ b/src/libcamera/v4l2_device.cpp
>> @@ -79,6 +79,15 @@ LOG_DEFINE_CATEGORY(V4L2)
>>   * \return True if the device can output video frames
>>   */
>>  
>> +/**
>> + * \fn bool V4L2Capability::isMeta()
>> + * \brief Identify if the device is capable of providing video meta-data
>> + *
>> + * FIXME: add support for META_OUTPUT, introduced in Linux v4.20
> 
> I think I saw Niklas suggest to make this a Todo: rather than fixme -
> but I don't think we need to worry too much over terminology that should
> be removed within a couple of weeks :D as We'll update this after the
> 5.0 is released.
> 
> 
> Likewise, I think the conditionals below might get some more thought put
> into them when we add in META_OUTPUT - but that's all future work.
> 
> This patch gets us closer.
> 
> Reviewed-by: Kieran Bingham <kieran.bingham@ideasonboard.com>
> 
> 
>> + *
>> + * \return True if the device can provide video meta-data
>> + */
>> +
>>  /**
>>   * \fn bool V4L2Capability::hasStreaming()
>>   * \brief Determine if the device can perform Streaming I/O
>> @@ -280,33 +289,32 @@ int V4L2Device::open()
>>  		<< "Opened device " << caps_.bus_info() << ": "
>>  		<< caps_.driver() << ": " << caps_.card();
>>  
>> -	if (!caps_.isCapture() && !caps_.isOutput()) {
>> -		LOG(V4L2, Debug) << "Device is not a supported type";
>> -		return -EINVAL;
>> -	}
>> -
>>  	if (!caps_.hasStreaming()) {
>>  		LOG(V4L2, Error) << "Device does not support streaming I/O";
>>  		return -EINVAL;
>>  	}
>>  
>> -	if (caps_.isCapture())
>> +	/*
>> +	 * Set buffer type and wait for read notifications on CAPTURE devices
>> +	 * (POLLIN), and write notifications for OUTPUT devices (POLLOUT).
>> +	 */
>> +	if (caps_.isCapture()) {
>> +		fdEvent_ = new EventNotifier(fd_, EventNotifier::Read);
>>  		bufferType_ = caps_.isMultiplanar()
>>  			    ? V4L2_BUF_TYPE_VIDEO_CAPTURE_MPLANE
>>  			    : V4L2_BUF_TYPE_VIDEO_CAPTURE;
>> -	else
>> +	} else if (caps_.isOutput()) {
>> +		fdEvent_ = new EventNotifier(fd_, EventNotifier::Write);
>>  		bufferType_ = caps_.isMultiplanar()
>>  			    ? V4L2_BUF_TYPE_VIDEO_OUTPUT_MPLANE
>>  			    : V4L2_BUF_TYPE_VIDEO_OUTPUT;
>> -
>> -	/*
>> -	 *  We wait for Read notifications on CAPTURE devices (POLLIN), and
>> -	 *  Write notifications for OUTPUT devices (POLLOUT).
>> -	 */
>> -	if (caps_.isCapture())
>> +	} else if (caps_.isMeta()) {
>>  		fdEvent_ = new EventNotifier(fd_, EventNotifier::Read);
>> -	else
>> -		fdEvent_ = new EventNotifier(fd_, EventNotifier::Write);
>> +		bufferType_ = V4L2_BUF_TYPE_META_CAPTURE;
>> +	} else {
>> +		LOG(V4L2, Debug) << "Device is not a supported type";
>> +		return -EINVAL;
>> +	}
>>  
>>  	fdEvent_->activated.connect(this, &V4L2Device::bufferAvailable);
>>  	fdEvent_->setEnabled(false);
>>
>
Jacopo Mondi Feb. 27, 2019, 9:05 a.m. UTC | #3
Hi Kieran,

On Tue, Feb 26, 2019 at 11:28:09PM +0000, Kieran Bingham wrote:
>
>
> On 26/02/2019 23:24, Kieran Bingham wrote:
> > Hi Jacopo,
> >
> > On 26/02/2019 16:26, Jacopo Mondi wrote:
> >> Add support for devices that provide video meta-data to v4l2_device.cpp
> >> and re-arrange bufferType handling in open() method.
> >>
> >> Signed-off-by: Jacopo Mondi <jacopo@jmondi.org>
> >> ---
> >>  src/libcamera/include/v4l2_device.h |  4 +++
> >>  src/libcamera/v4l2_device.cpp       | 38 +++++++++++++++++------------
> >>  2 files changed, 27 insertions(+), 15 deletions(-)
> >>
> >> diff --git a/src/libcamera/include/v4l2_device.h b/src/libcamera/include/v4l2_device.h
> >> index 1d31d1b403bc..52eb6785cc15 100644
> >> --- a/src/libcamera/include/v4l2_device.h
> >> +++ b/src/libcamera/include/v4l2_device.h
> >> @@ -53,6 +53,10 @@ struct V4L2Capability final : v4l2_capability {
> >>  		return device_caps() & (V4L2_CAP_VIDEO_CAPTURE |
> >>  					V4L2_CAP_VIDEO_CAPTURE_MPLANE);
> >>  	}
> >> +	bool isMeta() const
>
> One last thought here,
>
> I'm a bit concerned that if we have isMeta and isOutput handling this -
> we might end up with an ugly 2 x 2 matrix in if statements.
>
> Any pretty way to make this better?
>
> Or would it be cleaner to move towards:
>
> bool isMetaCapture()
> bool isMetaOutput()

In prevision of introducing support for META_OUTPUT, I have now named
this 'isMetaCapture()'.

I'm not so concerned about the if matrix, it will look like:

	if (caps_.isCapture()) {
		fdEvent_ = new EventNotifier(fd_, EventNotifier::Read);
		bufferType_ = caps_.isMultiplanar()
			    ? V4L2_BUF_TYPE_VIDEO_CAPTURE_MPLANE
			    : V4L2_BUF_TYPE_VIDEO_CAPTURE;
	} else if (caps_.isOutput()) {
		fdEvent_ = new EventNotifier(fd_, EventNotifier::Write);
		bufferType_ = caps_.isMultiplanar()
			    ? V4L2_BUF_TYPE_VIDEO_OUTPUT_MPLANE
			    : V4L2_BUF_TYPE_VIDEO_OUTPUT;
	} else if (caps_.isMetaCapture()) {
		fdEvent_ = new EventNotifier(fd_, EventNotifier::Read);
		bufferType_ = V4L2_BUF_TYPE_META_CAPTURE;
	} else if (caps_.isMetaOutput()) {
		fdEvent_ = new EventNotifier(fd_, EventNotifier::Write);
		bufferType_ = V4L2_BUF_TYPE_META_OUTPUT;
	} else {
		LOG(V4L2, Debug) << "Device is not a supported type";
		return -EINVAL;
	}

We could rename isCapture/isOutput to isVideoCapture/isVideoOutput for
simmetry, but I don't think that's a big deal, isn't it?

Thanks
  j

>
> This bit feels like a pain point - but I don't think that should stop
> this patch right now.
>
>
>
>
> >> +	{
> >> +		return device_caps() & V4L2_CAP_META_CAPTURE;
> >> +	}
> >>  	bool isOutput() const
> >>  	{
> >>  		return device_caps() & (V4L2_CAP_VIDEO_OUTPUT |
> >> diff --git a/src/libcamera/v4l2_device.cpp b/src/libcamera/v4l2_device.cpp
> >> index 24e115554a99..8be8af7a2893 100644
> >> --- a/src/libcamera/v4l2_device.cpp
> >> +++ b/src/libcamera/v4l2_device.cpp
> >> @@ -79,6 +79,15 @@ LOG_DEFINE_CATEGORY(V4L2)
> >>   * \return True if the device can output video frames
> >>   */
> >>
> >> +/**
> >> + * \fn bool V4L2Capability::isMeta()
> >> + * \brief Identify if the device is capable of providing video meta-data
> >> + *
> >> + * FIXME: add support for META_OUTPUT, introduced in Linux v4.20
> >
> > I think I saw Niklas suggest to make this a Todo: rather than fixme -
> > but I don't think we need to worry too much over terminology that should
> > be removed within a couple of weeks :D as We'll update this after the
> > 5.0 is released.
> >
> >
> > Likewise, I think the conditionals below might get some more thought put
> > into them when we add in META_OUTPUT - but that's all future work.
> >
> > This patch gets us closer.
> >
> > Reviewed-by: Kieran Bingham <kieran.bingham@ideasonboard.com>
> >
> >
> >> + *
> >> + * \return True if the device can provide video meta-data
> >> + */
> >> +
> >>  /**
> >>   * \fn bool V4L2Capability::hasStreaming()
> >>   * \brief Determine if the device can perform Streaming I/O
> >> @@ -280,33 +289,32 @@ int V4L2Device::open()
> >>  		<< "Opened device " << caps_.bus_info() << ": "
> >>  		<< caps_.driver() << ": " << caps_.card();
> >>
> >> -	if (!caps_.isCapture() && !caps_.isOutput()) {
> >> -		LOG(V4L2, Debug) << "Device is not a supported type";
> >> -		return -EINVAL;
> >> -	}
> >> -
> >>  	if (!caps_.hasStreaming()) {
> >>  		LOG(V4L2, Error) << "Device does not support streaming I/O";
> >>  		return -EINVAL;
> >>  	}
> >>
> >> -	if (caps_.isCapture())
> >> +	/*
> >> +	 * Set buffer type and wait for read notifications on CAPTURE devices
> >> +	 * (POLLIN), and write notifications for OUTPUT devices (POLLOUT).
> >> +	 */
> >> +	if (caps_.isCapture()) {
> >> +		fdEvent_ = new EventNotifier(fd_, EventNotifier::Read);
> >>  		bufferType_ = caps_.isMultiplanar()
> >>  			    ? V4L2_BUF_TYPE_VIDEO_CAPTURE_MPLANE
> >>  			    : V4L2_BUF_TYPE_VIDEO_CAPTURE;
> >> -	else
> >> +	} else if (caps_.isOutput()) {
> >> +		fdEvent_ = new EventNotifier(fd_, EventNotifier::Write);
> >>  		bufferType_ = caps_.isMultiplanar()
> >>  			    ? V4L2_BUF_TYPE_VIDEO_OUTPUT_MPLANE
> >>  			    : V4L2_BUF_TYPE_VIDEO_OUTPUT;
> >> -
> >> -	/*
> >> -	 *  We wait for Read notifications on CAPTURE devices (POLLIN), and
> >> -	 *  Write notifications for OUTPUT devices (POLLOUT).
> >> -	 */
> >> -	if (caps_.isCapture())
> >> +	} else if (caps_.isMeta()) {
> >>  		fdEvent_ = new EventNotifier(fd_, EventNotifier::Read);
> >> -	else
> >> -		fdEvent_ = new EventNotifier(fd_, EventNotifier::Write);
> >> +		bufferType_ = V4L2_BUF_TYPE_META_CAPTURE;
> >> +	} else {
> >> +		LOG(V4L2, Debug) << "Device is not a supported type";
> >> +		return -EINVAL;
> >> +	}
> >>
> >>  	fdEvent_->activated.connect(this, &V4L2Device::bufferAvailable);
> >>  	fdEvent_->setEnabled(false);
> >>
> >
>
> --
> Regards
> --
> Kieran
Laurent Pinchart Feb. 27, 2019, 5:54 p.m. UTC | #4
Hi Jacopo,

Thank you for the patch.

On Tue, Feb 26, 2019 at 05:26:36PM +0100, Jacopo Mondi wrote:
> Add support for devices that provide video meta-data to v4l2_device.cpp
> and re-arrange bufferType handling in open() method.
> 
> Signed-off-by: Jacopo Mondi <jacopo@jmondi.org>
> ---
>  src/libcamera/include/v4l2_device.h |  4 +++
>  src/libcamera/v4l2_device.cpp       | 38 +++++++++++++++++------------
>  2 files changed, 27 insertions(+), 15 deletions(-)
> 
> diff --git a/src/libcamera/include/v4l2_device.h b/src/libcamera/include/v4l2_device.h
> index 1d31d1b403bc..52eb6785cc15 100644
> --- a/src/libcamera/include/v4l2_device.h
> +++ b/src/libcamera/include/v4l2_device.h
> @@ -53,6 +53,10 @@ struct V4L2Capability final : v4l2_capability {
>  		return device_caps() & (V4L2_CAP_VIDEO_CAPTURE |
>  					V4L2_CAP_VIDEO_CAPTURE_MPLANE);
>  	}
> +	bool isMeta() const
> +	{
> +		return device_caps() & V4L2_CAP_META_CAPTURE;
> +	}
>  	bool isOutput() const
>  	{
>  		return device_caps() & (V4L2_CAP_VIDEO_OUTPUT |

Even if you don't introduce support for V4L2_CAP_META_OUTPUT now,
isCapture() should still return true for V4L2_CAP_META_CAPTURE to ease
transition later. Don't forget to update the isOutput() and isCapture()
documentation to not mention video frames anymore, but just output and
capture.

> diff --git a/src/libcamera/v4l2_device.cpp b/src/libcamera/v4l2_device.cpp
> index 24e115554a99..8be8af7a2893 100644
> --- a/src/libcamera/v4l2_device.cpp
> +++ b/src/libcamera/v4l2_device.cpp
> @@ -79,6 +79,15 @@ LOG_DEFINE_CATEGORY(V4L2)
>   * \return True if the device can output video frames
>   */
>  
> +/**
> + * \fn bool V4L2Capability::isMeta()
> + * \brief Identify if the device is capable of providing video meta-data
> + *
> + * FIXME: add support for META_OUTPUT, introduced in Linux v4.20

Maybe \todo ?

s/v4.20/v5.0/

> + *
> + * \return True if the device can provide video meta-data
> + */
> +
>  /**
>   * \fn bool V4L2Capability::hasStreaming()
>   * \brief Determine if the device can perform Streaming I/O
> @@ -280,33 +289,32 @@ int V4L2Device::open()
>  		<< "Opened device " << caps_.bus_info() << ": "
>  		<< caps_.driver() << ": " << caps_.card();
>  
> -	if (!caps_.isCapture() && !caps_.isOutput()) {
> -		LOG(V4L2, Debug) << "Device is not a supported type";
> -		return -EINVAL;
> -	}
> -
>  	if (!caps_.hasStreaming()) {
>  		LOG(V4L2, Error) << "Device does not support streaming I/O";
>  		return -EINVAL;
>  	}
>  
> -	if (caps_.isCapture())
> +	/*
> +	 * Set buffer type and wait for read notifications on CAPTURE devices
> +	 * (POLLIN), and write notifications for OUTPUT devices (POLLOUT).
> +	 */
> +	if (caps_.isCapture()) {
> +		fdEvent_ = new EventNotifier(fd_, EventNotifier::Read);
>  		bufferType_ = caps_.isMultiplanar()
>  			    ? V4L2_BUF_TYPE_VIDEO_CAPTURE_MPLANE
>  			    : V4L2_BUF_TYPE_VIDEO_CAPTURE;
> -	else
> +	} else if (caps_.isOutput()) {
> +		fdEvent_ = new EventNotifier(fd_, EventNotifier::Write);
>  		bufferType_ = caps_.isMultiplanar()
>  			    ? V4L2_BUF_TYPE_VIDEO_OUTPUT_MPLANE
>  			    : V4L2_BUF_TYPE_VIDEO_OUTPUT;
> -
> -	/*
> -	 *  We wait for Read notifications on CAPTURE devices (POLLIN), and
> -	 *  Write notifications for OUTPUT devices (POLLOUT).
> -	 */
> -	if (caps_.isCapture())
> +	} else if (caps_.isMeta()) {
>  		fdEvent_ = new EventNotifier(fd_, EventNotifier::Read);
> -	else
> -		fdEvent_ = new EventNotifier(fd_, EventNotifier::Write);
> +		bufferType_ = V4L2_BUF_TYPE_META_CAPTURE;
> +	} else {
> +		LOG(V4L2, Debug) << "Device is not a supported type";
> +		return -EINVAL;
> +	}
>  
>  	fdEvent_->activated.connect(this, &V4L2Device::bufferAvailable);
>  	fdEvent_->setEnabled(false);
Jacopo Mondi Feb. 28, 2019, 8:49 a.m. UTC | #5
Hi Laurent,

On Wed, Feb 27, 2019 at 07:54:18PM +0200, Laurent Pinchart wrote:
> Hi Jacopo,
>
> Thank you for the patch.
>
> On Tue, Feb 26, 2019 at 05:26:36PM +0100, Jacopo Mondi wrote:
> > Add support for devices that provide video meta-data to v4l2_device.cpp
> > and re-arrange bufferType handling in open() method.
> >
> > Signed-off-by: Jacopo Mondi <jacopo@jmondi.org>
> > ---
> >  src/libcamera/include/v4l2_device.h |  4 +++
> >  src/libcamera/v4l2_device.cpp       | 38 +++++++++++++++++------------
> >  2 files changed, 27 insertions(+), 15 deletions(-)
> >
> > diff --git a/src/libcamera/include/v4l2_device.h b/src/libcamera/include/v4l2_device.h
> > index 1d31d1b403bc..52eb6785cc15 100644
> > --- a/src/libcamera/include/v4l2_device.h
> > +++ b/src/libcamera/include/v4l2_device.h
> > @@ -53,6 +53,10 @@ struct V4L2Capability final : v4l2_capability {
> >  		return device_caps() & (V4L2_CAP_VIDEO_CAPTURE |
> >  					V4L2_CAP_VIDEO_CAPTURE_MPLANE);
> >  	}
> > +	bool isMeta() const
> > +	{
> > +		return device_caps() & V4L2_CAP_META_CAPTURE;
> > +	}
> >  	bool isOutput() const
> >  	{
> >  		return device_caps() & (V4L2_CAP_VIDEO_OUTPUT |
>
> Even if you don't introduce support for V4L2_CAP_META_OUTPUT now,
> isCapture() should still return true for V4L2_CAP_META_CAPTURE to ease
> transition later. Don't forget to update the isOutput() and isCapture()
> documentation to not mention video frames anymore, but just output and
> capture.
>

As done in v4, I introduced an isMetaCapture() method, preparing for
an isMetaOutput() one. In this way isCapture() and isOutput() would
refer to video streams only and the bufferType intialization looks
like:

	 * Set buffer type and wait for read notifications on CAPTURE devices
	 * (POLLIN), and write notifications for OUTPUT devices (POLLOUT).
	 */
	if (caps_.isCapture()) {
		fdEvent_ = new EventNotifier(fd_, EventNotifier::Read);
		bufferType_ = caps_.isMultiplanar()
			    ? V4L2_BUF_TYPE_VIDEO_CAPTURE_MPLANE
			    : V4L2_BUF_TYPE_VIDEO_CAPTURE;
	} else if (caps_.isOutput()) {
		fdEvent_ = new EventNotifier(fd_, EventNotifier::Write);
		bufferType_ = caps_.isMultiplanar()
			    ? V4L2_BUF_TYPE_VIDEO_OUTPUT_MPLANE
			    : V4L2_BUF_TYPE_VIDEO_OUTPUT;
	} else if (caps_.isMetaCapture()) {
		fdEvent_ = new EventNotifier(fd_, EventNotifier::Read);
		bufferType_ = V4L2_BUF_TYPE_META_CAPTURE;
	} else if (caps_.isMetaOutput()) {
		fdEvent_ = new EventNotifier(fd_, EventNotifier::Write);
		bufferType_ = V4L2_BUF_TYPE_META_OUTPUT;
	} else {
		LOG(V4L2, Debug) << "Device is not a supported type";
		return -EINVAL;
	}



> > diff --git a/src/libcamera/v4l2_device.cpp b/src/libcamera/v4l2_device.cpp
> > index 24e115554a99..8be8af7a2893 100644
> > --- a/src/libcamera/v4l2_device.cpp
> > +++ b/src/libcamera/v4l2_device.cpp
> > @@ -79,6 +79,15 @@ LOG_DEFINE_CATEGORY(V4L2)
> >   * \return True if the device can output video frames
> >   */
> >
> > +/**
> > + * \fn bool V4L2Capability::isMeta()
> > + * \brief Identify if the device is capable of providing video meta-data
> > + *
> > + * FIXME: add support for META_OUTPUT, introduced in Linux v4.20
>
> Maybe \todo ?
>
> s/v4.20/v5.0/
>
> > + *
> > + * \return True if the device can provide video meta-data
> > + */
> > +
> >  /**
> >   * \fn bool V4L2Capability::hasStreaming()
> >   * \brief Determine if the device can perform Streaming I/O
> > @@ -280,33 +289,32 @@ int V4L2Device::open()
> >  		<< "Opened device " << caps_.bus_info() << ": "
> >  		<< caps_.driver() << ": " << caps_.card();
> >
> > -	if (!caps_.isCapture() && !caps_.isOutput()) {
> > -		LOG(V4L2, Debug) << "Device is not a supported type";
> > -		return -EINVAL;
> > -	}
> > -
> >  	if (!caps_.hasStreaming()) {
> >  		LOG(V4L2, Error) << "Device does not support streaming I/O";
> >  		return -EINVAL;
> >  	}
> >
> > -	if (caps_.isCapture())
> > +	/*
> > +	 * Set buffer type and wait for read notifications on CAPTURE devices
> > +	 * (POLLIN), and write notifications for OUTPUT devices (POLLOUT).
> > +	 */
> > +	if (caps_.isCapture()) {
> > +		fdEvent_ = new EventNotifier(fd_, EventNotifier::Read);
> >  		bufferType_ = caps_.isMultiplanar()
> >  			    ? V4L2_BUF_TYPE_VIDEO_CAPTURE_MPLANE
> >  			    : V4L2_BUF_TYPE_VIDEO_CAPTURE;
> > -	else
> > +	} else if (caps_.isOutput()) {
> > +		fdEvent_ = new EventNotifier(fd_, EventNotifier::Write);
> >  		bufferType_ = caps_.isMultiplanar()
> >  			    ? V4L2_BUF_TYPE_VIDEO_OUTPUT_MPLANE
> >  			    : V4L2_BUF_TYPE_VIDEO_OUTPUT;
> > -
> > -	/*
> > -	 *  We wait for Read notifications on CAPTURE devices (POLLIN), and
> > -	 *  Write notifications for OUTPUT devices (POLLOUT).
> > -	 */
> > -	if (caps_.isCapture())
> > +	} else if (caps_.isMeta()) {
> >  		fdEvent_ = new EventNotifier(fd_, EventNotifier::Read);
> > -	else
> > -		fdEvent_ = new EventNotifier(fd_, EventNotifier::Write);
> > +		bufferType_ = V4L2_BUF_TYPE_META_CAPTURE;
> > +	} else {
> > +		LOG(V4L2, Debug) << "Device is not a supported type";
> > +		return -EINVAL;
> > +	}
> >
> >  	fdEvent_->activated.connect(this, &V4L2Device::bufferAvailable);
> >  	fdEvent_->setEnabled(false);
>
> --
> Regards,
>
> Laurent Pinchart
Laurent Pinchart Feb. 28, 2019, 5:25 p.m. UTC | #6
Hi Jacopo,

On Thu, Feb 28, 2019 at 09:49:53AM +0100, Jacopo Mondi wrote:
> On Wed, Feb 27, 2019 at 07:54:18PM +0200, Laurent Pinchart wrote:
> > On Tue, Feb 26, 2019 at 05:26:36PM +0100, Jacopo Mondi wrote:
> >> Add support for devices that provide video meta-data to v4l2_device.cpp
> >> and re-arrange bufferType handling in open() method.
> >>
> >> Signed-off-by: Jacopo Mondi <jacopo@jmondi.org>
> >> ---
> >>  src/libcamera/include/v4l2_device.h |  4 +++
> >>  src/libcamera/v4l2_device.cpp       | 38 +++++++++++++++++------------
> >>  2 files changed, 27 insertions(+), 15 deletions(-)
> >>
> >> diff --git a/src/libcamera/include/v4l2_device.h b/src/libcamera/include/v4l2_device.h
> >> index 1d31d1b403bc..52eb6785cc15 100644
> >> --- a/src/libcamera/include/v4l2_device.h
> >> +++ b/src/libcamera/include/v4l2_device.h
> >> @@ -53,6 +53,10 @@ struct V4L2Capability final : v4l2_capability {
> >>  		return device_caps() & (V4L2_CAP_VIDEO_CAPTURE |
> >>  					V4L2_CAP_VIDEO_CAPTURE_MPLANE);
> >>  	}
> >> +	bool isMeta() const
> >> +	{
> >> +		return device_caps() & V4L2_CAP_META_CAPTURE;
> >> +	}
> >>  	bool isOutput() const
> >>  	{
> >>  		return device_caps() & (V4L2_CAP_VIDEO_OUTPUT |
> >
> > Even if you don't introduce support for V4L2_CAP_META_OUTPUT now,
> > isCapture() should still return true for V4L2_CAP_META_CAPTURE to ease
> > transition later. Don't forget to update the isOutput() and isCapture()
> > documentation to not mention video frames anymore, but just output and
> > capture.
> >
> 
> As done in v4, I introduced an isMetaCapture() method, preparing for
> an isMetaOutput() one. In this way isCapture() and isOutput() would
> refer to video streams only and the bufferType intialization looks
> like:

That's confusing. Let's have

isCapture() -> V4L2_CAP_META_CAPTURE | V4L2_CAP_VIDEO_CAPTURE |
	       V4L2_CAP_VIDEO_CAPTURE_MPLANE
isOutput() -> V4L2_CAP_META_OUTPUT | V4L2_CAP_VIDEO_OUTPUT |
	      V4L2_CAP_VIDEO_OUTPUT_MPLANE
isMeta() -> V4L2_CAP_META_CAPTURE | V4L2_CAP_META_OUTPUT
isVideo() -> V4L2_CAP_VIDEO_CAPTURE | V4L2_CAP_VIDEO_CAPTURE_MPLANE |
	     V4L2_CAP_VIDEO_OUTPUT | V4L2_CAP_VIDEO_OUTPUT_MPLANE

and you can then also add, if desired,

isMetaCapture() -> isMeta() && isCapture()
...

> 
> 	 * Set buffer type and wait for read notifications on CAPTURE devices
> 	 * (POLLIN), and write notifications for OUTPUT devices (POLLOUT).
> 	 */
> 	if (caps_.isCapture()) {
> 		fdEvent_ = new EventNotifier(fd_, EventNotifier::Read);
> 		bufferType_ = caps_.isMultiplanar()
> 			    ? V4L2_BUF_TYPE_VIDEO_CAPTURE_MPLANE
> 			    : V4L2_BUF_TYPE_VIDEO_CAPTURE;
> 	} else if (caps_.isOutput()) {
> 		fdEvent_ = new EventNotifier(fd_, EventNotifier::Write);
> 		bufferType_ = caps_.isMultiplanar()
> 			    ? V4L2_BUF_TYPE_VIDEO_OUTPUT_MPLANE
> 			    : V4L2_BUF_TYPE_VIDEO_OUTPUT;
> 	} else if (caps_.isMetaCapture()) {
> 		fdEvent_ = new EventNotifier(fd_, EventNotifier::Read);
> 		bufferType_ = V4L2_BUF_TYPE_META_CAPTURE;
> 	} else if (caps_.isMetaOutput()) {
> 		fdEvent_ = new EventNotifier(fd_, EventNotifier::Write);
> 		bufferType_ = V4L2_BUF_TYPE_META_OUTPUT;
> 	} else {
> 		LOG(V4L2, Debug) << "Device is not a supported type";
> 		return -EINVAL;
> 	}
> 
> >> diff --git a/src/libcamera/v4l2_device.cpp b/src/libcamera/v4l2_device.cpp
> >> index 24e115554a99..8be8af7a2893 100644
> >> --- a/src/libcamera/v4l2_device.cpp
> >> +++ b/src/libcamera/v4l2_device.cpp
> >> @@ -79,6 +79,15 @@ LOG_DEFINE_CATEGORY(V4L2)
> >>   * \return True if the device can output video frames
> >>   */
> >>
> >> +/**
> >> + * \fn bool V4L2Capability::isMeta()
> >> + * \brief Identify if the device is capable of providing video meta-data
> >> + *
> >> + * FIXME: add support for META_OUTPUT, introduced in Linux v4.20
> >
> > Maybe \todo ?
> >
> > s/v4.20/v5.0/
> >
> >> + *
> >> + * \return True if the device can provide video meta-data
> >> + */
> >> +
> >>  /**
> >>   * \fn bool V4L2Capability::hasStreaming()
> >>   * \brief Determine if the device can perform Streaming I/O
> >> @@ -280,33 +289,32 @@ int V4L2Device::open()
> >>  		<< "Opened device " << caps_.bus_info() << ": "
> >>  		<< caps_.driver() << ": " << caps_.card();
> >>
> >> -	if (!caps_.isCapture() && !caps_.isOutput()) {
> >> -		LOG(V4L2, Debug) << "Device is not a supported type";
> >> -		return -EINVAL;
> >> -	}
> >> -
> >>  	if (!caps_.hasStreaming()) {
> >>  		LOG(V4L2, Error) << "Device does not support streaming I/O";
> >>  		return -EINVAL;
> >>  	}
> >>
> >> -	if (caps_.isCapture())
> >> +	/*
> >> +	 * Set buffer type and wait for read notifications on CAPTURE devices
> >> +	 * (POLLIN), and write notifications for OUTPUT devices (POLLOUT).
> >> +	 */
> >> +	if (caps_.isCapture()) {
> >> +		fdEvent_ = new EventNotifier(fd_, EventNotifier::Read);
> >>  		bufferType_ = caps_.isMultiplanar()
> >>  			    ? V4L2_BUF_TYPE_VIDEO_CAPTURE_MPLANE
> >>  			    : V4L2_BUF_TYPE_VIDEO_CAPTURE;
> >> -	else
> >> +	} else if (caps_.isOutput()) {
> >> +		fdEvent_ = new EventNotifier(fd_, EventNotifier::Write);
> >>  		bufferType_ = caps_.isMultiplanar()
> >>  			    ? V4L2_BUF_TYPE_VIDEO_OUTPUT_MPLANE
> >>  			    : V4L2_BUF_TYPE_VIDEO_OUTPUT;
> >> -
> >> -	/*
> >> -	 *  We wait for Read notifications on CAPTURE devices (POLLIN), and
> >> -	 *  Write notifications for OUTPUT devices (POLLOUT).
> >> -	 */
> >> -	if (caps_.isCapture())
> >> +	} else if (caps_.isMeta()) {
> >>  		fdEvent_ = new EventNotifier(fd_, EventNotifier::Read);
> >> -	else
> >> -		fdEvent_ = new EventNotifier(fd_, EventNotifier::Write);
> >> +		bufferType_ = V4L2_BUF_TYPE_META_CAPTURE;
> >> +	} else {
> >> +		LOG(V4L2, Debug) << "Device is not a supported type";
> >> +		return -EINVAL;
> >> +	}
> >>
> >>  	fdEvent_->activated.connect(this, &V4L2Device::bufferAvailable);
> >>  	fdEvent_->setEnabled(false);
Jacopo Mondi Feb. 28, 2019, 7:15 p.m. UTC | #7
Hi Laurent,

On Thu, Feb 28, 2019 at 07:25:49PM +0200, Laurent Pinchart wrote:
> Hi Jacopo,
>
> On Thu, Feb 28, 2019 at 09:49:53AM +0100, Jacopo Mondi wrote:
> > On Wed, Feb 27, 2019 at 07:54:18PM +0200, Laurent Pinchart wrote:
> > > On Tue, Feb 26, 2019 at 05:26:36PM +0100, Jacopo Mondi wrote:
> > >> Add support for devices that provide video meta-data to v4l2_device.cpp
> > >> and re-arrange bufferType handling in open() method.
> > >>
> > >> Signed-off-by: Jacopo Mondi <jacopo@jmondi.org>
> > >> ---
> > >>  src/libcamera/include/v4l2_device.h |  4 +++
> > >>  src/libcamera/v4l2_device.cpp       | 38 +++++++++++++++++------------
> > >>  2 files changed, 27 insertions(+), 15 deletions(-)
> > >>
> > >> diff --git a/src/libcamera/include/v4l2_device.h b/src/libcamera/include/v4l2_device.h
> > >> index 1d31d1b403bc..52eb6785cc15 100644
> > >> --- a/src/libcamera/include/v4l2_device.h
> > >> +++ b/src/libcamera/include/v4l2_device.h
> > >> @@ -53,6 +53,10 @@ struct V4L2Capability final : v4l2_capability {
> > >>  		return device_caps() & (V4L2_CAP_VIDEO_CAPTURE |
> > >>  					V4L2_CAP_VIDEO_CAPTURE_MPLANE);
> >

[snip]

> > As done in v4, I introduced an isMetaCapture() method, preparing for
> > an isMetaOutput() one. In this way isCapture() and isOutput() would
> > refer to video streams only and the bufferType intialization looks
> > like:
>
> That's confusing. Let's have
>
> isCapture() -> V4L2_CAP_META_CAPTURE | V4L2_CAP_VIDEO_CAPTURE |
> 	       V4L2_CAP_VIDEO_CAPTURE_MPLANE
> isOutput() -> V4L2_CAP_META_OUTPUT | V4L2_CAP_VIDEO_OUTPUT |
> 	      V4L2_CAP_VIDEO_OUTPUT_MPLANE
> isMeta() -> V4L2_CAP_META_CAPTURE | V4L2_CAP_META_OUTPUT
> isVideo() -> V4L2_CAP_VIDEO_CAPTURE | V4L2_CAP_VIDEO_CAPTURE_MPLANE |
> 	     V4L2_CAP_VIDEO_OUTPUT | V4L2_CAP_VIDEO_OUTPUT_MPLANE
>
> and you can then also add, if desired,
>
> isMetaCapture() -> isMeta() && isCapture()
> ...
>

I think the code below here, which is the only place where those
functions are used would become less nice if this case.

Those functions are only used to assign bufferType_ and fdEvent_,
let's keep it straightforward as the below series of if/else


> >
> > 	 * Set buffer type and wait for read notifications on CAPTURE devices
> > 	 * (POLLIN), and write notifications for OUTPUT devices (POLLOUT).
> > 	 */
> > 	if (caps_.isCapture()) {
> > 		fdEvent_ = new EventNotifier(fd_, EventNotifier::Read);
> > 		bufferType_ = caps_.isMultiplanar()
> > 			    ? V4L2_BUF_TYPE_VIDEO_CAPTURE_MPLANE
> > 			    : V4L2_BUF_TYPE_VIDEO_CAPTURE;
> > 	} else if (caps_.isOutput()) {
> > 		fdEvent_ = new EventNotifier(fd_, EventNotifier::Write);
> > 		bufferType_ = caps_.isMultiplanar()
> > 			    ? V4L2_BUF_TYPE_VIDEO_OUTPUT_MPLANE
> > 			    : V4L2_BUF_TYPE_VIDEO_OUTPUT;
> > 	} else if (caps_.isMetaCapture()) {
> > 		fdEvent_ = new EventNotifier(fd_, EventNotifier::Read);
> > 		bufferType_ = V4L2_BUF_TYPE_META_CAPTURE;
> > 	} else if (caps_.isMetaOutput()) {
> > 		fdEvent_ = new EventNotifier(fd_, EventNotifier::Write);
> > 		bufferType_ = V4L2_BUF_TYPE_META_OUTPUT;
> > 	} else {
> > 		LOG(V4L2, Debug) << "Device is not a supported type";
> > 		return -EINVAL;
> > 	}
> >
> > >> diff --git a/src/libcamera/v4l2_device.cpp b/src/libcamera/v4l2_device.cpp
> > >> index 24e115554a99..8be8af7a2893 100644
> > >> --- a/src/libcamera/v4l2_device.cpp
> > >> +++ b/src/libcamera/v4l2_device.cpp
> > >> @@ -79,6 +79,15 @@ LOG_DEFINE_CATEGORY(V4L2)
> > >>   * \return True if the device can output video frames
> > >>   */
> > >>
> > >> +/**
> > >> + * \fn bool V4L2Capability::isMeta()
> > >> + * \brief Identify if the device is capable of providing video meta-data
> > >> + *
> > >> + * FIXME: add support for META_OUTPUT, introduced in Linux v4.20
> > >
> > > Maybe \todo ?
> > >
> > > s/v4.20/v5.0/
> > >
> > >> + *
> > >> + * \return True if the device can provide video meta-data
> > >> + */
> > >> +
> > >>  /**
> > >>   * \fn bool V4L2Capability::hasStreaming()
> > >>   * \brief Determine if the device can perform Streaming I/O
> > >> @@ -280,33 +289,32 @@ int V4L2Device::open()
> > >>  		<< "Opened device " << caps_.bus_info() << ": "
> > >>  		<< caps_.driver() << ": " << caps_.card();
> > >>
> > >> -	if (!caps_.isCapture() && !caps_.isOutput()) {
> > >> -		LOG(V4L2, Debug) << "Device is not a supported type";
> > >> -		return -EINVAL;
> > >> -	}
> > >> -
> > >>  	if (!caps_.hasStreaming()) {
> > >>  		LOG(V4L2, Error) << "Device does not support streaming I/O";
> > >>  		return -EINVAL;
> > >>  	}
> > >>
> > >> -	if (caps_.isCapture())
> > >> +	/*
> > >> +	 * Set buffer type and wait for read notifications on CAPTURE devices
> > >> +	 * (POLLIN), and write notifications for OUTPUT devices (POLLOUT).
> > >> +	 */
> > >> +	if (caps_.isCapture()) {
> > >> +		fdEvent_ = new EventNotifier(fd_, EventNotifier::Read);
> > >>  		bufferType_ = caps_.isMultiplanar()
> > >>  			    ? V4L2_BUF_TYPE_VIDEO_CAPTURE_MPLANE
> > >>  			    : V4L2_BUF_TYPE_VIDEO_CAPTURE;
> > >> -	else
> > >> +	} else if (caps_.isOutput()) {
> > >> +		fdEvent_ = new EventNotifier(fd_, EventNotifier::Write);
> > >>  		bufferType_ = caps_.isMultiplanar()
> > >>  			    ? V4L2_BUF_TYPE_VIDEO_OUTPUT_MPLANE
> > >>  			    : V4L2_BUF_TYPE_VIDEO_OUTPUT;
> > >> -
> > >> -	/*
> > >> -	 *  We wait for Read notifications on CAPTURE devices (POLLIN), and
> > >> -	 *  Write notifications for OUTPUT devices (POLLOUT).
> > >> -	 */
> > >> -	if (caps_.isCapture())
> > >> +	} else if (caps_.isMeta()) {
> > >>  		fdEvent_ = new EventNotifier(fd_, EventNotifier::Read);
> > >> -	else
> > >> -		fdEvent_ = new EventNotifier(fd_, EventNotifier::Write);
> > >> +		bufferType_ = V4L2_BUF_TYPE_META_CAPTURE;
> > >> +	} else {
> > >> +		LOG(V4L2, Debug) << "Device is not a supported type";
> > >> +		return -EINVAL;
> > >> +	}
> > >>
> > >>  	fdEvent_->activated.connect(this, &V4L2Device::bufferAvailable);
> > >>  	fdEvent_->setEnabled(false);
>
> --
> Regards,
>
> Laurent Pinchart
Laurent Pinchart Feb. 28, 2019, 9:45 p.m. UTC | #8
Hi Jacopo,

On Thu, Feb 28, 2019 at 08:15:57PM +0100, Jacopo Mondi wrote:
> On Thu, Feb 28, 2019 at 07:25:49PM +0200, Laurent Pinchart wrote:
> > On Thu, Feb 28, 2019 at 09:49:53AM +0100, Jacopo Mondi wrote:
> >> On Wed, Feb 27, 2019 at 07:54:18PM +0200, Laurent Pinchart wrote:
> >>> On Tue, Feb 26, 2019 at 05:26:36PM +0100, Jacopo Mondi wrote:
> >>>> Add support for devices that provide video meta-data to v4l2_device.cpp
> >>>> and re-arrange bufferType handling in open() method.
> >>>>
> >>>> Signed-off-by: Jacopo Mondi <jacopo@jmondi.org>
> >>>> ---
> >>>>  src/libcamera/include/v4l2_device.h |  4 +++
> >>>>  src/libcamera/v4l2_device.cpp       | 38 +++++++++++++++++------------
> >>>>  2 files changed, 27 insertions(+), 15 deletions(-)
> >>>>
> >>>> diff --git a/src/libcamera/include/v4l2_device.h b/src/libcamera/include/v4l2_device.h
> >>>> index 1d31d1b403bc..52eb6785cc15 100644
> >>>> --- a/src/libcamera/include/v4l2_device.h
> >>>> +++ b/src/libcamera/include/v4l2_device.h
> >>>> @@ -53,6 +53,10 @@ struct V4L2Capability final : v4l2_capability {
> >>>>  		return device_caps() & (V4L2_CAP_VIDEO_CAPTURE |
> >>>>  					V4L2_CAP_VIDEO_CAPTURE_MPLANE);
> 
> [snip]
> 
> >> As done in v4, I introduced an isMetaCapture() method, preparing for
> >> an isMetaOutput() one. In this way isCapture() and isOutput() would
> >> refer to video streams only and the bufferType intialization looks
> >> like:
> >
> > That's confusing. Let's have
> >
> > isCapture() -> V4L2_CAP_META_CAPTURE | V4L2_CAP_VIDEO_CAPTURE |
> > 	       V4L2_CAP_VIDEO_CAPTURE_MPLANE
> > isOutput() -> V4L2_CAP_META_OUTPUT | V4L2_CAP_VIDEO_OUTPUT |
> > 	      V4L2_CAP_VIDEO_OUTPUT_MPLANE
> > isMeta() -> V4L2_CAP_META_CAPTURE | V4L2_CAP_META_OUTPUT
> > isVideo() -> V4L2_CAP_VIDEO_CAPTURE | V4L2_CAP_VIDEO_CAPTURE_MPLANE |
> > 	     V4L2_CAP_VIDEO_OUTPUT | V4L2_CAP_VIDEO_OUTPUT_MPLANE
> >
> > and you can then also add, if desired,
> >
> > isMetaCapture() -> isMeta() && isCapture()
> > ...
> >
> 
> I think the code below here, which is the only place where those
> functions are used would become less nice if this case.
> 
> Those functions are only used to assign bufferType_ and fdEvent_,
> let's keep it straightforward as the below series of if/else

The code below is fine, my point is that isCapture() should not mean
isVideoCapture().

	bool isCapture() const
	{
		return device_caps() & (V4L2_CAP_META_CAPTURE |
					V4L2_CAP_VIDEO_CAPTURE |
					V4L2_CAP_VIDEO_CAPTURE_MPLANE);
	}

	bool isOutput() const
	{
		return device_caps() & (V4L2_CAP_META_OUTPUT |
					V4L2_CAP_VIDEO_OUTPUT |
					V4L2_CAP_VIDEO_OUTPUT_MPLANE);
	}

	bool isMeta() const
	{
		return device_caps() & (V4L2_CAP_META_CAPTURE |
					V4L2_CAP_META_OUTPUT);
	}

	bool isVideo() const
	{
		return device_caps() & (V4L2_CAP_VIDEO_CAPTURE |
					V4L2_CAP_VIDEO_CAPTURE_MPLANE |
					V4L2_CAP_VIDEO_OUTPUT |
					V4L2_CAP_VIDEO_OUTPUT_MPLANE);
	}

	bool isMetaCapture() const
	{
		return isMeta() && isCapture();
	}

	bool isMetaOutput() const
	{
		return isMeta() && isOutput();
	}

	bool isVideoCapture() const
	{
		return isVideo() && isCapture();
	}

	bool isVideoOutput() const
	{
		return isVideo() && isOutput();
	}

and then use those four last functions below.

> >>
> >> 	 * Set buffer type and wait for read notifications on CAPTURE devices
> >> 	 * (POLLIN), and write notifications for OUTPUT devices (POLLOUT).
> >> 	 */
> >> 	if (caps_.isCapture()) {
> >> 		fdEvent_ = new EventNotifier(fd_, EventNotifier::Read);
> >> 		bufferType_ = caps_.isMultiplanar()
> >> 			    ? V4L2_BUF_TYPE_VIDEO_CAPTURE_MPLANE
> >> 			    : V4L2_BUF_TYPE_VIDEO_CAPTURE;
> >> 	} else if (caps_.isOutput()) {
> >> 		fdEvent_ = new EventNotifier(fd_, EventNotifier::Write);
> >> 		bufferType_ = caps_.isMultiplanar()
> >> 			    ? V4L2_BUF_TYPE_VIDEO_OUTPUT_MPLANE
> >> 			    : V4L2_BUF_TYPE_VIDEO_OUTPUT;
> >> 	} else if (caps_.isMetaCapture()) {
> >> 		fdEvent_ = new EventNotifier(fd_, EventNotifier::Read);
> >> 		bufferType_ = V4L2_BUF_TYPE_META_CAPTURE;
> >> 	} else if (caps_.isMetaOutput()) {
> >> 		fdEvent_ = new EventNotifier(fd_, EventNotifier::Write);
> >> 		bufferType_ = V4L2_BUF_TYPE_META_OUTPUT;
> >> 	} else {
> >> 		LOG(V4L2, Debug) << "Device is not a supported type";
> >> 		return -EINVAL;
> >> 	}
> >>
Jacopo Mondi March 1, 2019, 9:40 a.m. UTC | #9
Hi Laurent,

On Thu, Feb 28, 2019 at 11:45:37PM +0200, Laurent Pinchart wrote:
> Hi Jacopo,
>
> On Thu, Feb 28, 2019 at 08:15:57PM +0100, Jacopo Mondi wrote:
> > On Thu, Feb 28, 2019 at 07:25:49PM +0200, Laurent Pinchart wrote:
> > > On Thu, Feb 28, 2019 at 09:49:53AM +0100, Jacopo Mondi wrote:
> > >> On Wed, Feb 27, 2019 at 07:54:18PM +0200, Laurent Pinchart wrote:
> > >>> On Tue, Feb 26, 2019 at 05:26:36PM +0100, Jacopo Mondi wrote:
> > >>>> Add support for devices that provide video meta-data to v4l2_device.cpp
> > >>>> and re-arrange bufferType handling in open() method.
> > >>>>
> > >>>> Signed-off-by: Jacopo Mondi <jacopo@jmondi.org>
> > >>>> ---
> > >>>>  src/libcamera/include/v4l2_device.h |  4 +++
> > >>>>  src/libcamera/v4l2_device.cpp       | 38 +++++++++++++++++------------
> > >>>>  2 files changed, 27 insertions(+), 15 deletions(-)
> > >>>>
> > >>>> diff --git a/src/libcamera/include/v4l2_device.h b/src/libcamera/include/v4l2_device.h
> > >>>> index 1d31d1b403bc..52eb6785cc15 100644
> > >>>> --- a/src/libcamera/include/v4l2_device.h
> > >>>> +++ b/src/libcamera/include/v4l2_device.h
> > >>>> @@ -53,6 +53,10 @@ struct V4L2Capability final : v4l2_capability {
> > >>>>  		return device_caps() & (V4L2_CAP_VIDEO_CAPTURE |
> > >>>>  					V4L2_CAP_VIDEO_CAPTURE_MPLANE);
> >
> > [snip]
> >
> > >> As done in v4, I introduced an isMetaCapture() method, preparing for
> > >> an isMetaOutput() one. In this way isCapture() and isOutput() would
> > >> refer to video streams only and the bufferType intialization looks
> > >> like:
> > >
> > > That's confusing. Let's have
> > >
> > > isCapture() -> V4L2_CAP_META_CAPTURE | V4L2_CAP_VIDEO_CAPTURE |
> > > 	       V4L2_CAP_VIDEO_CAPTURE_MPLANE
> > > isOutput() -> V4L2_CAP_META_OUTPUT | V4L2_CAP_VIDEO_OUTPUT |
> > > 	      V4L2_CAP_VIDEO_OUTPUT_MPLANE
> > > isMeta() -> V4L2_CAP_META_CAPTURE | V4L2_CAP_META_OUTPUT
> > > isVideo() -> V4L2_CAP_VIDEO_CAPTURE | V4L2_CAP_VIDEO_CAPTURE_MPLANE |
> > > 	     V4L2_CAP_VIDEO_OUTPUT | V4L2_CAP_VIDEO_OUTPUT_MPLANE
> > >
> > > and you can then also add, if desired,
> > >
> > > isMetaCapture() -> isMeta() && isCapture()
> > > ...
> > >
> >
> > I think the code below here, which is the only place where those
> > functions are used would become less nice if this case.
> >
> > Those functions are only used to assign bufferType_ and fdEvent_,
> > let's keep it straightforward as the below series of if/else
>
> The code below is fine, my point is that isCapture() should not mean
> isVideoCapture().
>
> 	bool isCapture() const
> 	{
> 		return device_caps() & (V4L2_CAP_META_CAPTURE |
> 					V4L2_CAP_VIDEO_CAPTURE |
> 					V4L2_CAP_VIDEO_CAPTURE_MPLANE);
> 	}
>
> 	bool isOutput() const
> 	{
> 		return device_caps() & (V4L2_CAP_META_OUTPUT |
> 					V4L2_CAP_VIDEO_OUTPUT |
> 					V4L2_CAP_VIDEO_OUTPUT_MPLANE);
> 	}
>
> 	bool isMeta() const
> 	{
> 		return device_caps() & (V4L2_CAP_META_CAPTURE |
> 					V4L2_CAP_META_OUTPUT);
> 	}
>
> 	bool isVideo() const
> 	{
> 		return device_caps() & (V4L2_CAP_VIDEO_CAPTURE |
> 					V4L2_CAP_VIDEO_CAPTURE_MPLANE |
> 					V4L2_CAP_VIDEO_OUTPUT |
> 					V4L2_CAP_VIDEO_OUTPUT_MPLANE);
> 	}
>
> 	bool isMetaCapture() const
> 	{
> 		return isMeta() && isCapture();
> 	}
>
> 	bool isMetaOutput() const
> 	{
> 		return isMeta() && isOutput();
> 	}
>
> 	bool isVideoCapture() const
> 	{
> 		return isVideo() && isCapture();
> 	}
>
> 	bool isVideoOutput() const
> 	{
> 		return isVideo() && isOutput();
> 	}
>
> and then use those four last functions below.

I see. I don't feel like adding 4 functions and one level of
indirection is super useful considering this is
used in a single place, but if that would help moving forward I'll
change this.

>
> > >>
> > >> 	 * Set buffer type and wait for read notifications on CAPTURE devices
> > >> 	 * (POLLIN), and write notifications for OUTPUT devices (POLLOUT).
> > >> 	 */
> > >> 	if (caps_.isCapture()) {
> > >> 		fdEvent_ = new EventNotifier(fd_, EventNotifier::Read);
> > >> 		bufferType_ = caps_.isMultiplanar()
> > >> 			    ? V4L2_BUF_TYPE_VIDEO_CAPTURE_MPLANE
> > >> 			    : V4L2_BUF_TYPE_VIDEO_CAPTURE;
> > >> 	} else if (caps_.isOutput()) {
> > >> 		fdEvent_ = new EventNotifier(fd_, EventNotifier::Write);
> > >> 		bufferType_ = caps_.isMultiplanar()
> > >> 			    ? V4L2_BUF_TYPE_VIDEO_OUTPUT_MPLANE
> > >> 			    : V4L2_BUF_TYPE_VIDEO_OUTPUT;
> > >> 	} else if (caps_.isMetaCapture()) {
> > >> 		fdEvent_ = new EventNotifier(fd_, EventNotifier::Read);
> > >> 		bufferType_ = V4L2_BUF_TYPE_META_CAPTURE;
> > >> 	} else if (caps_.isMetaOutput()) {
> > >> 		fdEvent_ = new EventNotifier(fd_, EventNotifier::Write);
> > >> 		bufferType_ = V4L2_BUF_TYPE_META_OUTPUT;
> > >> 	} else {
> > >> 		LOG(V4L2, Debug) << "Device is not a supported type";
> > >> 		return -EINVAL;
> > >> 	}
> > >>
>
> --
> Regards,
>
> Laurent Pinchart
Laurent Pinchart March 1, 2019, 9:53 a.m. UTC | #10
Hi Jacopo,

On Fri, Mar 01, 2019 at 10:40:46AM +0100, Jacopo Mondi wrote:
> On Thu, Feb 28, 2019 at 11:45:37PM +0200, Laurent Pinchart wrote:
> > On Thu, Feb 28, 2019 at 08:15:57PM +0100, Jacopo Mondi wrote:
> >> On Thu, Feb 28, 2019 at 07:25:49PM +0200, Laurent Pinchart wrote:
> >>> On Thu, Feb 28, 2019 at 09:49:53AM +0100, Jacopo Mondi wrote:
> >>>> On Wed, Feb 27, 2019 at 07:54:18PM +0200, Laurent Pinchart wrote:
> >>>>> On Tue, Feb 26, 2019 at 05:26:36PM +0100, Jacopo Mondi wrote:
> >>>>>> Add support for devices that provide video meta-data to v4l2_device.cpp
> >>>>>> and re-arrange bufferType handling in open() method.
> >>>>>>
> >>>>>> Signed-off-by: Jacopo Mondi <jacopo@jmondi.org>
> >>>>>> ---
> >>>>>>  src/libcamera/include/v4l2_device.h |  4 +++
> >>>>>>  src/libcamera/v4l2_device.cpp       | 38 +++++++++++++++++------------
> >>>>>>  2 files changed, 27 insertions(+), 15 deletions(-)
> >>>>>>
> >>>>>> diff --git a/src/libcamera/include/v4l2_device.h b/src/libcamera/include/v4l2_device.h
> >>>>>> index 1d31d1b403bc..52eb6785cc15 100644
> >>>>>> --- a/src/libcamera/include/v4l2_device.h
> >>>>>> +++ b/src/libcamera/include/v4l2_device.h
> >>>>>> @@ -53,6 +53,10 @@ struct V4L2Capability final : v4l2_capability {
> >>>>>>  		return device_caps() & (V4L2_CAP_VIDEO_CAPTURE |
> >>>>>>  					V4L2_CAP_VIDEO_CAPTURE_MPLANE);
> >>
> >> [snip]
> >>
> >>>> As done in v4, I introduced an isMetaCapture() method, preparing for
> >>>> an isMetaOutput() one. In this way isCapture() and isOutput() would
> >>>> refer to video streams only and the bufferType intialization looks
> >>>> like:
> >>>
> >>> That's confusing. Let's have
> >>>
> >>> isCapture() -> V4L2_CAP_META_CAPTURE | V4L2_CAP_VIDEO_CAPTURE |
> >>> 	       V4L2_CAP_VIDEO_CAPTURE_MPLANE
> >>> isOutput() -> V4L2_CAP_META_OUTPUT | V4L2_CAP_VIDEO_OUTPUT |
> >>> 	      V4L2_CAP_VIDEO_OUTPUT_MPLANE
> >>> isMeta() -> V4L2_CAP_META_CAPTURE | V4L2_CAP_META_OUTPUT
> >>> isVideo() -> V4L2_CAP_VIDEO_CAPTURE | V4L2_CAP_VIDEO_CAPTURE_MPLANE |
> >>> 	     V4L2_CAP_VIDEO_OUTPUT | V4L2_CAP_VIDEO_OUTPUT_MPLANE
> >>>
> >>> and you can then also add, if desired,
> >>>
> >>> isMetaCapture() -> isMeta() && isCapture()
> >>> ...
> >>>
> >>
> >> I think the code below here, which is the only place where those
> >> functions are used would become less nice if this case.
> >>
> >> Those functions are only used to assign bufferType_ and fdEvent_,
> >> let's keep it straightforward as the below series of if/else
> >
> > The code below is fine, my point is that isCapture() should not mean
> > isVideoCapture().
> >
> > 	bool isCapture() const
> > 	{
> > 		return device_caps() & (V4L2_CAP_META_CAPTURE |
> > 					V4L2_CAP_VIDEO_CAPTURE |
> > 					V4L2_CAP_VIDEO_CAPTURE_MPLANE);
> > 	}
> >
> > 	bool isOutput() const
> > 	{
> > 		return device_caps() & (V4L2_CAP_META_OUTPUT |
> > 					V4L2_CAP_VIDEO_OUTPUT |
> > 					V4L2_CAP_VIDEO_OUTPUT_MPLANE);
> > 	}
> >
> > 	bool isMeta() const
> > 	{
> > 		return device_caps() & (V4L2_CAP_META_CAPTURE |
> > 					V4L2_CAP_META_OUTPUT);
> > 	}
> >
> > 	bool isVideo() const
> > 	{
> > 		return device_caps() & (V4L2_CAP_VIDEO_CAPTURE |
> > 					V4L2_CAP_VIDEO_CAPTURE_MPLANE |
> > 					V4L2_CAP_VIDEO_OUTPUT |
> > 					V4L2_CAP_VIDEO_OUTPUT_MPLANE);
> > 	}
> >
> > 	bool isMetaCapture() const
> > 	{
> > 		return isMeta() && isCapture();
> > 	}
> >
> > 	bool isMetaOutput() const
> > 	{
> > 		return isMeta() && isOutput();
> > 	}
> >
> > 	bool isVideoCapture() const
> > 	{
> > 		return isVideo() && isCapture();
> > 	}
> >
> > 	bool isVideoOutput() const
> > 	{
> > 		return isVideo() && isOutput();
> > 	}
> >
> > and then use those four last functions below.
> 
> I see. I don't feel like adding 4 functions and one level of
> indirection is super useful considering this is
> used in a single place, but if that would help moving forward I'll
> change this.

You can get rid of the level of indirection if you prefer (although the
compiler should really optimize this), but what I really want is
s/isCapture/isVideoCapture/ and s/isOutput/isVideoOutput/.

> >>>>
> >>>> 	 * Set buffer type and wait for read notifications on CAPTURE devices
> >>>> 	 * (POLLIN), and write notifications for OUTPUT devices (POLLOUT).
> >>>> 	 */
> >>>> 	if (caps_.isCapture()) {
> >>>> 		fdEvent_ = new EventNotifier(fd_, EventNotifier::Read);
> >>>> 		bufferType_ = caps_.isMultiplanar()
> >>>> 			    ? V4L2_BUF_TYPE_VIDEO_CAPTURE_MPLANE
> >>>> 			    : V4L2_BUF_TYPE_VIDEO_CAPTURE;
> >>>> 	} else if (caps_.isOutput()) {
> >>>> 		fdEvent_ = new EventNotifier(fd_, EventNotifier::Write);
> >>>> 		bufferType_ = caps_.isMultiplanar()
> >>>> 			    ? V4L2_BUF_TYPE_VIDEO_OUTPUT_MPLANE
> >>>> 			    : V4L2_BUF_TYPE_VIDEO_OUTPUT;
> >>>> 	} else if (caps_.isMetaCapture()) {
> >>>> 		fdEvent_ = new EventNotifier(fd_, EventNotifier::Read);
> >>>> 		bufferType_ = V4L2_BUF_TYPE_META_CAPTURE;
> >>>> 	} else if (caps_.isMetaOutput()) {
> >>>> 		fdEvent_ = new EventNotifier(fd_, EventNotifier::Write);
> >>>> 		bufferType_ = V4L2_BUF_TYPE_META_OUTPUT;
> >>>> 	} else {
> >>>> 		LOG(V4L2, Debug) << "Device is not a supported type";
> >>>> 		return -EINVAL;
> >>>> 	}
> >>>>

Patch

diff --git a/src/libcamera/include/v4l2_device.h b/src/libcamera/include/v4l2_device.h
index 1d31d1b403bc..52eb6785cc15 100644
--- a/src/libcamera/include/v4l2_device.h
+++ b/src/libcamera/include/v4l2_device.h
@@ -53,6 +53,10 @@  struct V4L2Capability final : v4l2_capability {
 		return device_caps() & (V4L2_CAP_VIDEO_CAPTURE |
 					V4L2_CAP_VIDEO_CAPTURE_MPLANE);
 	}
+	bool isMeta() const
+	{
+		return device_caps() & V4L2_CAP_META_CAPTURE;
+	}
 	bool isOutput() const
 	{
 		return device_caps() & (V4L2_CAP_VIDEO_OUTPUT |
diff --git a/src/libcamera/v4l2_device.cpp b/src/libcamera/v4l2_device.cpp
index 24e115554a99..8be8af7a2893 100644
--- a/src/libcamera/v4l2_device.cpp
+++ b/src/libcamera/v4l2_device.cpp
@@ -79,6 +79,15 @@  LOG_DEFINE_CATEGORY(V4L2)
  * \return True if the device can output video frames
  */
 
+/**
+ * \fn bool V4L2Capability::isMeta()
+ * \brief Identify if the device is capable of providing video meta-data
+ *
+ * FIXME: add support for META_OUTPUT, introduced in Linux v4.20
+ *
+ * \return True if the device can provide video meta-data
+ */
+
 /**
  * \fn bool V4L2Capability::hasStreaming()
  * \brief Determine if the device can perform Streaming I/O
@@ -280,33 +289,32 @@  int V4L2Device::open()
 		<< "Opened device " << caps_.bus_info() << ": "
 		<< caps_.driver() << ": " << caps_.card();
 
-	if (!caps_.isCapture() && !caps_.isOutput()) {
-		LOG(V4L2, Debug) << "Device is not a supported type";
-		return -EINVAL;
-	}
-
 	if (!caps_.hasStreaming()) {
 		LOG(V4L2, Error) << "Device does not support streaming I/O";
 		return -EINVAL;
 	}
 
-	if (caps_.isCapture())
+	/*
+	 * Set buffer type and wait for read notifications on CAPTURE devices
+	 * (POLLIN), and write notifications for OUTPUT devices (POLLOUT).
+	 */
+	if (caps_.isCapture()) {
+		fdEvent_ = new EventNotifier(fd_, EventNotifier::Read);
 		bufferType_ = caps_.isMultiplanar()
 			    ? V4L2_BUF_TYPE_VIDEO_CAPTURE_MPLANE
 			    : V4L2_BUF_TYPE_VIDEO_CAPTURE;
-	else
+	} else if (caps_.isOutput()) {
+		fdEvent_ = new EventNotifier(fd_, EventNotifier::Write);
 		bufferType_ = caps_.isMultiplanar()
 			    ? V4L2_BUF_TYPE_VIDEO_OUTPUT_MPLANE
 			    : V4L2_BUF_TYPE_VIDEO_OUTPUT;
-
-	/*
-	 *  We wait for Read notifications on CAPTURE devices (POLLIN), and
-	 *  Write notifications for OUTPUT devices (POLLOUT).
-	 */
-	if (caps_.isCapture())
+	} else if (caps_.isMeta()) {
 		fdEvent_ = new EventNotifier(fd_, EventNotifier::Read);
-	else
-		fdEvent_ = new EventNotifier(fd_, EventNotifier::Write);
+		bufferType_ = V4L2_BUF_TYPE_META_CAPTURE;
+	} else {
+		LOG(V4L2, Debug) << "Device is not a supported type";
+		return -EINVAL;
+	}
 
 	fdEvent_->activated.connect(this, &V4L2Device::bufferAvailable);
 	fdEvent_->setEnabled(false);