[libcamera-devel,v2,2/2] libcamera: Introduce V4L2Device base class

1416 diff mbox series

he V4L2 devices and subdevices share a few common operations,like
opening and closing a device node, and perform IOCTLs on the device.

With the forthcoming introduction of support for V4L2 controls, the
quantity of shared code will drastically increase, as the control
implementation is identical for the two.

To maximize code re-use and avoid duplications, provide a V4L2Device
base class which groups the common operations and members.

The newly introduced base class provides methods to open/close a device
node, access the file descriptor, and perform IOCTLs on the device.

Signed-off-by: Jacopo Mondi <jacopo@jmondi.org>
Signed-off-by: Kieran Bingham <kieran.bingham@ideasonboard.com>
---
 src/libcamera/include/v4l2_device.h      |  36 ++++++
 src/libcamera/include/v4l2_subdevice.h   |   6 +-
 src/libcamera/include/v4l2_videodevice.h |   5 +-
 src/libcamera/meson.build                |   2 +
 src/libcamera/v4l2_device.cpp            | 148 +++++++++++++++++++++++
 src/libcamera/v4l2_subdevice.cpp         |  66 +++-------
 src/libcamera/v4l2_videodevice.cpp       |  68 ++++-------
 7 files changed, 227 insertions(+), 104 deletions(-)
 create mode 100644 src/libcamera/include/v4l2_device.h
 create mode 100644 src/libcamera/v4l2_device.cpp

Hi Jacopo,

On 12/06/2019 14:38, Jacopo Mondi wrote:
> he V4L2 devices and subdevices share a few common operations,like

s/he/The/

> opening and closing a device node, and perform IOCTLs on the device.
> 
> With the forthcoming introduction of support for V4L2 controls, the
> quantity of shared code will drastically increase, as the control
> implementation is identical for the two.
> 
> To maximize code re-use and avoid duplications, provide a V4L2Device
> base class which groups the common operations and members.
> 
> The newly introduced base class provides methods to open/close a device
> node, access the file descriptor, and perform IOCTLs on the device.
> 
> Signed-off-by: Jacopo Mondi <jacopo@jmondi.org>
> Signed-off-by: Kieran Bingham <kieran.bingham@ideasonboard.com>


Thank you - this is much easier to review now :-D


A few comments below:

> ---
>  src/libcamera/include/v4l2_device.h      |  36 ++++++
>  src/libcamera/include/v4l2_subdevice.h   |   6 +-
>  src/libcamera/include/v4l2_videodevice.h |   5 +-
>  src/libcamera/meson.build                |   2 +
>  src/libcamera/v4l2_device.cpp            | 148 +++++++++++++++++++++++
>  src/libcamera/v4l2_subdevice.cpp         |  66 +++-------
>  src/libcamera/v4l2_videodevice.cpp       |  68 ++++-------
>  7 files changed, 227 insertions(+), 104 deletions(-)
>  create mode 100644 src/libcamera/include/v4l2_device.h
>  create mode 100644 src/libcamera/v4l2_device.cpp
> 
> diff --git a/src/libcamera/include/v4l2_device.h b/src/libcamera/include/v4l2_device.h
> new file mode 100644
> index 000000000000..584a570a4703
> --- /dev/null
> +++ b/src/libcamera/include/v4l2_device.h
> @@ -0,0 +1,36 @@
> +/* SPDX-License-Identifier: LGPL-2.1-or-later */
> +/*
> + * Copyright (C) 2019, Google Inc.
> + *
> + * v4l2_device.h - Common base for V4L2 video devices and subdevices
> + */
> +#ifndef __LIBCAMERA_V4L2_DEVICE_H__
> +#define __LIBCAMERA_V4L2_DEVICE_H__
> +
> +#include <string>
> +
> +namespace libcamera {
> +
> +class V4L2Device
> +{
> +public:
> +	virtual ~V4L2Device() { close(); }
> +
> +protected:
> +	V4L2Device();
> +
> +	int fd() { return fd_; }
> +
> +	int open(const std::string &pathname, unsigned int flags);
> +	int close();
> +	bool isOpen() const;
> +
> +	int ioctl(unsigned long request, void *argp);
> +
> +private:
> +	int fd_;
> +};
> +
> +} /* namespace libcamera */
> +
> +#endif /* __LIBCAMERA_V4L2_DEVICE_H__ */
> diff --git a/src/libcamera/include/v4l2_subdevice.h b/src/libcamera/include/v4l2_subdevice.h
> index 3e4e5107aebe..a34b719f8c52 100644
> --- a/src/libcamera/include/v4l2_subdevice.h
> +++ b/src/libcamera/include/v4l2_subdevice.h
> @@ -16,6 +16,7 @@
>  #include "formats.h"
>  #include "log.h"
>  #include "media_object.h"
> +#include "v4l2_device.h"
>  
>  namespace libcamera {
>  
> @@ -28,7 +29,7 @@ struct V4L2SubdeviceFormat {
>  	const std::string toString() const;
>  };
>  
> -class V4L2Subdevice : protected Loggable
> +class V4L2Subdevice : public V4L2Device, protected Loggable
>  {
>  public:
>  	explicit V4L2Subdevice(const MediaEntity *entity);
> @@ -37,8 +38,6 @@ public:
>  	~V4L2Subdevice();
>  
>  	int open();
> -	bool isOpen() const;
> -	void close();
>  
>  	const MediaEntity *entity() const { return entity_; }
>  
> @@ -64,7 +63,6 @@ private:
>  			 Rectangle *rect);
>  
>  	const MediaEntity *entity_;
> -	int fd_;
>  };
>  
>  } /* namespace libcamera */
> diff --git a/src/libcamera/include/v4l2_videodevice.h b/src/libcamera/include/v4l2_videodevice.h
> index 6ecdb64e5f3c..15a83635b9bf 100644
> --- a/src/libcamera/include/v4l2_videodevice.h
> +++ b/src/libcamera/include/v4l2_videodevice.h
> @@ -17,6 +17,7 @@
>  #include <libcamera/signal.h>
>  
>  #include "log.h"
> +#include "v4l2_device.h"
>  
>  namespace libcamera {
>  
> @@ -111,7 +112,7 @@ public:
>  	const std::string toString() const;
>  };
>  
> -class V4L2VideoDevice : protected Loggable
> +class V4L2VideoDevice : public V4L2Device, protected Loggable
>  {
>  public:
>  	explicit V4L2VideoDevice(const std::string &deviceNode);
> @@ -122,7 +123,6 @@ public:
>  	V4L2VideoDevice &operator=(const V4L2VideoDevice &) = delete;
>  
>  	int open();
> -	bool isOpen() const;
>  	void close();
>  
>  	const char *driverName() const { return caps_.driver(); }
> @@ -167,7 +167,6 @@ private:
>  	void bufferAvailable(EventNotifier *notifier);
>  
>  	std::string deviceNode_;
> -	int fd_;
>  	V4L2Capability caps_;
>  
>  	enum v4l2_buf_type bufferType_;
> diff --git a/src/libcamera/meson.build b/src/libcamera/meson.build
> index 15ab53b1abbe..f26ad5b2dc57 100644
> --- a/src/libcamera/meson.build
> +++ b/src/libcamera/meson.build
> @@ -23,6 +23,7 @@ libcamera_sources = files([
>      'stream.cpp',
>      'timer.cpp',
>      'utils.cpp',
> +    'v4l2_device.cpp',
>      'v4l2_subdevice.cpp',
>      'v4l2_videodevice.cpp',
>  ])
> @@ -41,6 +42,7 @@ libcamera_headers = files([
>      'include/media_object.h',
>      'include/pipeline_handler.h',
>      'include/utils.h',
> +    'include/v4l2_device.h',
>      'include/v4l2_subdevice.h',
>      'include/v4l2_videodevice.h',
>  ])
> diff --git a/src/libcamera/v4l2_device.cpp b/src/libcamera/v4l2_device.cpp
> new file mode 100644
> index 000000000000..f89b2a2982ba
> --- /dev/null
> +++ b/src/libcamera/v4l2_device.cpp
> @@ -0,0 +1,148 @@
> +/* SPDX-License-Identifier: LGPL-2.1-or-later */
> +/*
> + * Copyright (C) 2019, Google Inc.
> + *
> + * v4l2_device.cpp - Common base for V4L2 devices and subdevices
> + */
> +
> +#include "v4l2_device.h"
> +
> +#include <fcntl.h>
> +#include <string.h>
> +#include <sys/ioctl.h>
> +#include <unistd.h>
> +
> +#include "log.h"
> +
> +/**
> + * \file v4l2_device.h
> + * \brief Common base for V4L2 devices and subdevices
> + */
> +
> +namespace libcamera {
> +
> +LOG_DEFINE_CATEGORY(V4L2)
> +
> +/**
> + * \class V4L2Device
> + * \brief Base class for V4L2Videodev and V4L2Subdev
> + *
> + * The V4L2Device class groups together the methods and fields common to
> + * both V4L2Videodev and V4L2Subdev, and provide a base class which
> + * provides methods to open and close the device node associated with the
> + * device and to perform IOCTL system calls on it.
> + *
> + * The V4L2Device class cannot be instantiated directly, as its constructor
> + * is protected. Users should use instead one the derived classes to model
> + * either a V4L2 video device or a V4L2 subdevice.
> + */
> +
> +/**
> + * \brief Construct a V4L2Device
> + *
> + * The V4L2Device constructor is protected and can only be accessed by the
> + * V4L2Videodev and V4L2Subdev derived classes.
> + *
> + * Initialize the file descriptor to -1.
> + */
> +V4L2Device::V4L2Device()
> +	: fd_(-1)
> +{
> +}
> +
> +/**
> + * \fn V4L2Device::fd()
> + * \brief Retrieve the V4L2 device file descriptor
> + * \return The V4L2 device file descriptor, -1 if the device node is not open
> + */
> +
> +/**
> + * \brief Open a V4L2 device node
> + * \param pathname The filesystem path of the device node to open
> + * \param flags Access mode flags
> + *
> + * Initialize the file descriptor, which was initially set to -1.
> + *
> + * \return 0 on success or a negative error code otherwise
> + */
> +int V4L2Device::open(const std::string &pathname, unsigned int flags)
> +{
> +	if (isOpen()) {
> +		LOG(V4L2, Error) << "Device already open";
> +		return -EBUSY;
> +	}
> +
> +	int ret = ::open(pathname.c_str(), flags);
> +	if (ret < 0) {
> +		ret = -errno;
> +		LOG(V4L2, Error) << "Failed to open V4L2 device: "
> +				 << strerror(-ret);
> +		return ret;
> +	}
> +
> +	fd_ = ret;
> +
> +	return 0;
> +}
> +
> +/**
> + * \brief Close the device node
> + *
> + * Reset the file descriptor to -1
> + *
> + * \return 0 on success or a negative error code otherwise
> + */
> +int V4L2Device::close()
> +{
> +	if (fd_ < 0)
> +		return 0;
> +
> +	int ret = ::close(fd_);
> +	if (ret < 0) {
> +		ret = -errno;
> +		LOG(V4L2, Error) << "Failed to close V4L2 device: "
> +				 << strerror(-ret);
> +		return ret;
> +	}
> +
> +	fd_ = -1;
> +
> +	return 0;
> +}
> +
> +/**
> + * \brief Check if the V4L2 device node is open
> + * \return True if the V4L2 device node is open, false otherwise
> + */
> +bool V4L2Device::isOpen() const
> +{
> +	return fd_ != -1;
> +}
> +
> +/**
> + * \brief Perform an IOCTL system call on the device node
> + * \param request The IOCTL request code
> + * \param argp A poiunter to the IOCTL argument


s/poiunter/pointer/


> + * \return 0 on success or a negative error code otherwise
> + */
> +int V4L2Device::ioctl(unsigned long request, void *argp)
> +{
> +	/*
> +	 * Printing out an error message is usually better performed
> +	 * in the caller, which can provide more context.
> +	 */
> +	if (::ioctl(fd_, request, argp) < 0)
> +		return -errno;

I /really/ like this ... but note how many of the call sites for
V4L2Device::ioctl() still work with the -errno fuss, which should now
just deal directly with 'ret' where it's used.

'man ioctl' states:

RETURN VALUE
       Usually,  on  success zero is returned.  A few ioctl() requests
       use the return value as an output parameter and return a
       nonnegative value on success.  On error, -1 is returned, and
       errno is set appropriately.


I really like simplifying the -1, errno check pattern that is
everywhere. But do we need to be sure we'll never need the return code
of the ioctl?

(I don't think we do - and we /could/ have a different call for that if
necessary)



> +
> +	return 0;
> +}
> +
> +/**
> + * \var V4L2Device::fd_
> + * \brief The V4L2 device node file descriptor
> + *
> + * The file descriptor is initialized to -1 and reset to this value once
> + * the device node gets closed.
> + */
> +
> +} /* namespace libcamera */
> diff --git a/src/libcamera/v4l2_subdevice.cpp b/src/libcamera/v4l2_subdevice.cpp
> index 6681c1920065..b1e5f559b944 100644
> --- a/src/libcamera/v4l2_subdevice.cpp
> +++ b/src/libcamera/v4l2_subdevice.cpp
> @@ -29,7 +29,7 @@
>  
>  namespace libcamera {
>  
> -LOG_DEFINE_CATEGORY(V4L2Subdev)
> +LOG_DECLARE_CATEGORY(V4L2)
>  
>  /**
>   * \struct V4L2SubdeviceFormat
> @@ -102,7 +102,7 @@ const std::string V4L2SubdeviceFormat::toString() const
>   * path
>   */
>  V4L2Subdevice::V4L2Subdevice(const MediaEntity *entity)
> -	: entity_(entity), fd_(-1)
> +	: V4L2Device(), entity_(entity)
>  {
>  }
>  
> @@ -117,45 +117,7 @@ V4L2Subdevice::~V4L2Subdevice()
>   */
>  int V4L2Subdevice::open()
>  {
> -	int ret;
> -
> -	if (isOpen()) {
> -		LOG(V4L2Subdev, Error) << "Device already open";
> -		return -EBUSY;
> -	}
> -
> -	ret = ::open(entity_->deviceNode().c_str(), O_RDWR);
> -	if (ret < 0) {
> -		ret = -errno;
> -		LOG(V4L2Subdev, Error)
> -			<< "Failed to open V4L2 subdevice '"
> -			<< entity_->deviceNode() << "': " << strerror(-ret);
> -		return ret;
> -	}
> -	fd_ = ret;
> -
> -	return 0;
> -}
> -
> -/**
> - * \brief Check if the subdevice is open
> - * \return True if the subdevice is open, false otherwise
> - */
> -bool V4L2Subdevice::isOpen() const
> -{
> -	return fd_ != -1;
> -}
> -
> -/**
> - * \brief Close the subdevice, releasing any resources acquired by open()
> - */
> -void V4L2Subdevice::close()
> -{
> -	if (!isOpen())
> -		return;
> -
> -	::close(fd_);
> -	fd_ = -1;
> +	return V4L2Device::open(entity_->deviceNode(), O_RDWR);
>  }
>  
>  /**
> @@ -207,7 +169,7 @@ FormatEnum V4L2Subdevice::formats(unsigned int pad)
>  	int ret;
>  
>  	if (pad >= entity_->pads().size()) {
> -		LOG(V4L2Subdev, Error) << "Invalid pad: " << pad;
> +		LOG(V4L2, Error) << "Invalid pad: " << pad;
>  		return formatMap;
>  	}
>  
> @@ -215,7 +177,7 @@ FormatEnum V4L2Subdevice::formats(unsigned int pad)
>  	mbusEnum.index = 0;
>  	mbusEnum.which = V4L2_SUBDEV_FORMAT_ACTIVE;
>  	while (true) {
> -		ret = ioctl(fd_, VIDIOC_SUBDEV_ENUM_MBUS_CODE, &mbusEnum);
> +		ret = ioctl(VIDIOC_SUBDEV_ENUM_MBUS_CODE, &mbusEnum);
>  		if (ret)
>  			break;
>  
> @@ -229,7 +191,7 @@ FormatEnum V4L2Subdevice::formats(unsigned int pad)
>  
>  	if (ret && (errno != EINVAL && errno != ENOTTY)) {
>  		ret = -errno;
> -		LOG(V4L2Subdev, Error)
> +		LOG(V4L2, Error)
>  			<< "Unable to enumerate formats on pad " << pad
>  			<< ": " << strerror(-ret);
>  		formatMap.clear();
> @@ -250,10 +212,10 @@ int V4L2Subdevice::getFormat(unsigned int pad, V4L2SubdeviceFormat *format)
>  	subdevFmt.which = V4L2_SUBDEV_FORMAT_ACTIVE;
>  	subdevFmt.pad = pad;
>  
> -	int ret = ioctl(fd_, VIDIOC_SUBDEV_G_FMT, &subdevFmt);
> +	int ret = ioctl(VIDIOC_SUBDEV_G_FMT, &subdevFmt);
>  	if (ret) {
>  		ret = -errno;
> -		LOG(V4L2Subdev, Error)
> +		LOG(V4L2, Error)
>  			<< "Unable to get format on pad " << pad
>  			<< ": " << strerror(-ret);
>  		return ret;
> @@ -286,10 +248,10 @@ int V4L2Subdevice::setFormat(unsigned int pad, V4L2SubdeviceFormat *format)
>  	subdevFmt.format.height = format->size.height;
>  	subdevFmt.format.code = format->mbus_code;
>  
> -	int ret = ioctl(fd_, VIDIOC_SUBDEV_S_FMT, &subdevFmt);
> +	int ret = ioctl(VIDIOC_SUBDEV_S_FMT, &subdevFmt);
>  	if (ret) {
>  		ret = -errno;
> -		LOG(V4L2Subdev, Error)
> +		LOG(V4L2, Error)
>  			<< "Unable to set format on pad " << pad
>  			<< ": " << strerror(-ret);
>  		return ret;
> @@ -339,7 +301,7 @@ int V4L2Subdevice::enumPadSizes(unsigned int pad,unsigned int code,
>  	sizeEnum.code = code;
>  	sizeEnum.which = V4L2_SUBDEV_FORMAT_ACTIVE;
>  	while (true) {
> -		ret = ioctl(fd_, VIDIOC_SUBDEV_ENUM_FRAME_SIZE, &sizeEnum);
> +		ret = ioctl(VIDIOC_SUBDEV_ENUM_FRAME_SIZE, &sizeEnum);
>  		if (ret)
>  			break;
>  
> @@ -351,7 +313,7 @@ int V4L2Subdevice::enumPadSizes(unsigned int pad,unsigned int code,
>  
>  	if (ret && (errno != EINVAL && errno != ENOTTY)) {
>  		ret = -errno;
> -		LOG(V4L2Subdev, Error)
> +		LOG(V4L2, Error)
>  			<< "Unable to enumerate sizes on pad " << pad
>  			<< ": " << strerror(-ret);
>  		sizes->clear();
> @@ -377,10 +339,10 @@ int V4L2Subdevice::setSelection(unsigned int pad, unsigned int target,
>  	sel.r.width = rect->w;
>  	sel.r.height = rect->h;
>  
> -	int ret = ioctl(fd_, VIDIOC_SUBDEV_S_SELECTION, &sel);
> +	int ret = ioctl(VIDIOC_SUBDEV_S_SELECTION, &sel);
>  	if (ret < 0) {
>  		ret = -errno;
> -		LOG(V4L2Subdev, Error)
> +		LOG(V4L2, Error)
>  			<< "Unable to set rectangle " << target << " on pad "
>  			<< pad << ": " << strerror(-ret);
>  		return ret;
> diff --git a/src/libcamera/v4l2_videodevice.cpp b/src/libcamera/v4l2_videodevice.cpp
> index 8957cf8f97d3..14e711d5dde3 100644
> --- a/src/libcamera/v4l2_videodevice.cpp
> +++ b/src/libcamera/v4l2_videodevice.cpp
> @@ -30,7 +30,7 @@
>   */
>  namespace libcamera {
>  
> -LOG_DEFINE_CATEGORY(V4L2)
> +LOG_DECLARE_CATEGORY(V4L2)
>  
>  /**
>   * \struct V4L2Capability
> @@ -270,7 +270,7 @@ const std::string V4L2DeviceFormat::toString() const
>   * \param[in] deviceNode The file-system path to the video device node
>   */
>  V4L2VideoDevice::V4L2VideoDevice(const std::string &deviceNode)
> -	: deviceNode_(deviceNode), fd_(-1), bufferPool_(nullptr),
> +	: V4L2Device(), deviceNode_(deviceNode), bufferPool_(nullptr),
>  	  queuedBuffersCount_(0), fdEvent_(nullptr)
>  {
>  	/*
> @@ -305,21 +305,11 @@ int V4L2VideoDevice::open()
>  {
>  	int ret;
>  
> -	if (isOpen()) {
> -		LOG(V4L2, Error) << "Device already open";
> -		return -EBUSY;
> -	}
> -
> -	ret = ::open(deviceNode_.c_str(), O_RDWR | O_NONBLOCK);
> -	if (ret < 0) {
> -		ret = -errno;
> -		LOG(V4L2, Error)
> -			<< "Failed to open V4L2 device: " << strerror(-ret);
> +	ret = V4L2Device::open(deviceNode_, O_RDWR | O_NONBLOCK);
> +	if (ret < 0)
>  		return ret;
> -	}
> -	fd_ = ret;
>  
> -	ret = ioctl(fd_, VIDIOC_QUERYCAP, &caps_);
> +	ret = ioctl(VIDIOC_QUERYCAP, &caps_);
>  	if (ret < 0) {
>  		ret = -errno;
>  		LOG(V4L2, Error)
> @@ -342,20 +332,20 @@ int V4L2VideoDevice::open()
>  	 * (POLLIN), and write notifications for OUTPUT devices (POLLOUT).
>  	 */
>  	if (caps_.isVideoCapture()) {
> -		fdEvent_ = new EventNotifier(fd_, EventNotifier::Read);
> +		fdEvent_ = new EventNotifier(fd(), EventNotifier::Read);
>  		bufferType_ = caps_.isMultiplanar()
>  			    ? V4L2_BUF_TYPE_VIDEO_CAPTURE_MPLANE
>  			    : V4L2_BUF_TYPE_VIDEO_CAPTURE;
>  	} else if (caps_.isVideoOutput()) {
> -		fdEvent_ = new EventNotifier(fd_, EventNotifier::Write);
> +		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);
> +		fdEvent_ = new EventNotifier(fd(), EventNotifier::Read);
>  		bufferType_ = V4L2_BUF_TYPE_META_CAPTURE;
>  	} else if (caps_.isMetaOutput()) {
> -		fdEvent_ = new EventNotifier(fd_, EventNotifier::Write);
> +		fdEvent_ = new EventNotifier(fd(), EventNotifier::Write);
>  		bufferType_ = V4L2_BUF_TYPE_META_OUTPUT;
>  	} else {
>  		LOG(V4L2, Error) << "Device is not a supported type";
> @@ -368,28 +358,16 @@ int V4L2VideoDevice::open()
>  	return 0;
>  }
>  
> -/**
> - * \brief Check if device is successfully opened
> - * \return True if the device is open, false otherwise
> - */
> -bool V4L2VideoDevice::isOpen() const
> -{
> -	return fd_ != -1;
> -}
> -
>  /**
>   * \brief Close the device, releasing any resources acquired by open()
>   */
>  void V4L2VideoDevice::close()
>  {
> -	if (fd_ < 0)
> +	if (fd() < 0)
>  		return;
>  
>  	releaseBuffers();
>  	delete fdEvent_;
> -
> -	::close(fd_);
> -	fd_ = -1;
>  }
>  
>  /**
> @@ -462,7 +440,7 @@ int V4L2VideoDevice::getFormatMeta(V4L2DeviceFormat *format)
>  	int ret;
>  
>  	v4l2Format.type = bufferType_;
> -	ret = ioctl(fd_, VIDIOC_G_FMT, &v4l2Format);
> +	ret = ioctl(VIDIOC_G_FMT, &v4l2Format);


I really like that ioctl now knows about the FD internally and thus is
simpler :)

"do this action with this structure..."


>  	if (ret) {
>  		ret = -errno;
>  		LOG(V4L2, Error) << "Unable to get format: " << strerror(-ret);

This is an example of things that I think should now be:

ret = ioctl(VIDIOC_G_FMT, &v4l2Format);
if (ret) {
	LOG(V4L2, Error) << "Unable to get format: " << strerror(ret);
	...
}

That probably applies to all uses of V4L2Device::ioctl()


> @@ -488,7 +466,7 @@ int V4L2VideoDevice::setFormatMeta(V4L2DeviceFormat *format)
>  	v4l2Format.type = bufferType_;
>  	pix->dataformat = format->fourcc;
>  	pix->buffersize = format->planes[0].size;
> -	ret = ioctl(fd_, VIDIOC_S_FMT, &v4l2Format);
> +	ret = ioctl(VIDIOC_S_FMT, &v4l2Format);
>  	if (ret) {
>  		ret = -errno;
>  		LOG(V4L2, Error) << "Unable to set format: " << strerror(-ret);
> @@ -516,7 +494,7 @@ int V4L2VideoDevice::getFormatMultiplane(V4L2DeviceFormat *format)
>  	int ret;
>  
>  	v4l2Format.type = bufferType_;
> -	ret = ioctl(fd_, VIDIOC_G_FMT, &v4l2Format);
> +	ret = ioctl(VIDIOC_G_FMT, &v4l2Format);
>  	if (ret) {
>  		ret = -errno;
>  		LOG(V4L2, Error) << "Unable to get format: " << strerror(-ret);
> @@ -554,7 +532,7 @@ int V4L2VideoDevice::setFormatMultiplane(V4L2DeviceFormat *format)
>  		pix->plane_fmt[i].sizeimage = format->planes[i].size;
>  	}
>  
> -	ret = ioctl(fd_, VIDIOC_S_FMT, &v4l2Format);
> +	ret = ioctl(VIDIOC_S_FMT, &v4l2Format);
>  	if (ret) {
>  		ret = -errno;
>  		LOG(V4L2, Error) << "Unable to set format: " << strerror(-ret);
> @@ -584,7 +562,7 @@ int V4L2VideoDevice::getFormatSingleplane(V4L2DeviceFormat *format)
>  	int ret;
>  
>  	v4l2Format.type = bufferType_;
> -	ret = ioctl(fd_, VIDIOC_G_FMT, &v4l2Format);
> +	ret = ioctl(VIDIOC_G_FMT, &v4l2Format);
>  	if (ret) {
>  		ret = -errno;
>  		LOG(V4L2, Error) << "Unable to get format: " << strerror(-ret);
> @@ -613,7 +591,7 @@ int V4L2VideoDevice::setFormatSingleplane(V4L2DeviceFormat *format)
>  	pix->pixelformat = format->fourcc;
>  	pix->bytesperline = format->planes[0].bpl;
>  	pix->field = V4L2_FIELD_NONE;
> -	ret = ioctl(fd_, VIDIOC_S_FMT, &v4l2Format);
> +	ret = ioctl(VIDIOC_S_FMT, &v4l2Format);
>  	if (ret) {
>  		ret = -errno;
>  		LOG(V4L2, Error) << "Unable to set format: " << strerror(-ret);
> @@ -643,7 +621,7 @@ int V4L2VideoDevice::requestBuffers(unsigned int count)
>  	rb.type = bufferType_;
>  	rb.memory = memoryType_;
>  
> -	ret = ioctl(fd_, VIDIOC_REQBUFS, &rb);
> +	ret = ioctl(VIDIOC_REQBUFS, &rb);
>  	if (ret < 0) {
>  		ret = -errno;
>  		LOG(V4L2, Error)
> @@ -695,7 +673,7 @@ int V4L2VideoDevice::exportBuffers(BufferPool *pool)
>  		buf.length = VIDEO_MAX_PLANES;
>  		buf.m.planes = planes;
>  
> -		ret = ioctl(fd_, VIDIOC_QUERYBUF, &buf);
> +		ret = ioctl(VIDIOC_QUERYBUF, &buf);
>  		if (ret < 0) {
>  			ret = -errno;
>  			LOG(V4L2, Error)
> @@ -748,7 +726,7 @@ int V4L2VideoDevice::createPlane(Buffer *buffer, unsigned int planeIndex,
>  	expbuf.plane = planeIndex;
>  	expbuf.flags = O_RDWR;
>  
> -	ret = ioctl(fd_, VIDIOC_EXPBUF, &expbuf);
> +	ret = ioctl(VIDIOC_EXPBUF, &expbuf);
>  	if (ret < 0) {
>  		ret = -errno;
>  		LOG(V4L2, Error)
> @@ -855,7 +833,7 @@ int V4L2VideoDevice::queueBuffer(Buffer *buffer)
>  
>  	LOG(V4L2, Debug) << "Queueing buffer " << buf.index;
>  
> -	ret = ioctl(fd_, VIDIOC_QBUF, &buf);
> +	ret = ioctl(VIDIOC_QBUF, &buf);
>  	if (ret < 0) {
>  		ret = -errno;
>  		LOG(V4L2, Error)
> @@ -892,7 +870,7 @@ Buffer *V4L2VideoDevice::dequeueBuffer()
>  		buf.m.planes = planes;
>  	}
>  
> -	ret = ioctl(fd_, VIDIOC_DQBUF, &buf);
> +	ret = ioctl(VIDIOC_DQBUF, &buf);
>  	if (ret < 0) {
>  		ret = -errno;
>  		LOG(V4L2, Error)
> @@ -952,7 +930,7 @@ int V4L2VideoDevice::streamOn()
>  {
>  	int ret;
>  
> -	ret = ioctl(fd_, VIDIOC_STREAMON, &bufferType_);
> +	ret = ioctl(VIDIOC_STREAMON, &bufferType_);
>  	if (ret < 0) {
>  		ret = -errno;
>  		LOG(V4L2, Error)
> @@ -975,7 +953,7 @@ int V4L2VideoDevice::streamOff()
>  {
>  	int ret;
>  
> -	ret = ioctl(fd_, VIDIOC_STREAMOFF, &bufferType_);
> +	ret = ioctl(VIDIOC_STREAMOFF, &bufferType_);
>  	if (ret < 0) {
>  		ret = -errno;
>  		LOG(V4L2, Error)
>

Oh and,

On 12/06/2019 14:50, Kieran Bingham wrote:
> Hi Jacopo,
> 
> On 12/06/2019 14:38, Jacopo Mondi wrote:
>> he V4L2 devices and subdevices share a few common operations,like
> 
> s/he/The/
> 
>> opening and closing a device node, and perform IOCTLs on the device.
>>
>> With the forthcoming introduction of support for V4L2 controls, the
>> quantity of shared code will drastically increase, as the control
>> implementation is identical for the two.
>>
>> To maximize code re-use and avoid duplications, provide a V4L2Device
>> base class which groups the common operations and members.
>>
>> The newly introduced base class provides methods to open/close a device
>> node, access the file descriptor, and perform IOCTLs on the device.
>>
>> Signed-off-by: Jacopo Mondi <jacopo@jmondi.org>
>> Signed-off-by: Kieran Bingham <kieran.bingham@ideasonboard.com>
> 
> 
> Thank you - this is much easier to review now :-D
> 
> 
> A few comments below:

With comments addressed as you see fit,

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


> 
>> ---
>>  src/libcamera/include/v4l2_device.h      |  36 ++++++
>>  src/libcamera/include/v4l2_subdevice.h   |   6 +-
>>  src/libcamera/include/v4l2_videodevice.h |   5 +-
>>  src/libcamera/meson.build                |   2 +
>>  src/libcamera/v4l2_device.cpp            | 148 +++++++++++++++++++++++
>>  src/libcamera/v4l2_subdevice.cpp         |  66 +++-------
>>  src/libcamera/v4l2_videodevice.cpp       |  68 ++++-------
>>  7 files changed, 227 insertions(+), 104 deletions(-)
>>  create mode 100644 src/libcamera/include/v4l2_device.h
>>  create mode 100644 src/libcamera/v4l2_device.cpp
>>
>> diff --git a/src/libcamera/include/v4l2_device.h b/src/libcamera/include/v4l2_device.h
>> new file mode 100644
>> index 000000000000..584a570a4703
>> --- /dev/null
>> +++ b/src/libcamera/include/v4l2_device.h
>> @@ -0,0 +1,36 @@
>> +/* SPDX-License-Identifier: LGPL-2.1-or-later */
>> +/*
>> + * Copyright (C) 2019, Google Inc.
>> + *
>> + * v4l2_device.h - Common base for V4L2 video devices and subdevices
>> + */
>> +#ifndef __LIBCAMERA_V4L2_DEVICE_H__
>> +#define __LIBCAMERA_V4L2_DEVICE_H__
>> +
>> +#include <string>
>> +
>> +namespace libcamera {
>> +
>> +class V4L2Device
>> +{
>> +public:
>> +	virtual ~V4L2Device() { close(); }
>> +
>> +protected:
>> +	V4L2Device();
>> +
>> +	int fd() { return fd_; }
>> +
>> +	int open(const std::string &pathname, unsigned int flags);
>> +	int close();
>> +	bool isOpen() const;
>> +
>> +	int ioctl(unsigned long request, void *argp);
>> +
>> +private:
>> +	int fd_;
>> +};
>> +
>> +} /* namespace libcamera */
>> +
>> +#endif /* __LIBCAMERA_V4L2_DEVICE_H__ */
>> diff --git a/src/libcamera/include/v4l2_subdevice.h b/src/libcamera/include/v4l2_subdevice.h
>> index 3e4e5107aebe..a34b719f8c52 100644
>> --- a/src/libcamera/include/v4l2_subdevice.h
>> +++ b/src/libcamera/include/v4l2_subdevice.h
>> @@ -16,6 +16,7 @@
>>  #include "formats.h"
>>  #include "log.h"
>>  #include "media_object.h"
>> +#include "v4l2_device.h"
>>  
>>  namespace libcamera {
>>  
>> @@ -28,7 +29,7 @@ struct V4L2SubdeviceFormat {
>>  	const std::string toString() const;
>>  };
>>  
>> -class V4L2Subdevice : protected Loggable
>> +class V4L2Subdevice : public V4L2Device, protected Loggable
>>  {
>>  public:
>>  	explicit V4L2Subdevice(const MediaEntity *entity);
>> @@ -37,8 +38,6 @@ public:
>>  	~V4L2Subdevice();
>>  
>>  	int open();
>> -	bool isOpen() const;
>> -	void close();
>>  
>>  	const MediaEntity *entity() const { return entity_; }
>>  
>> @@ -64,7 +63,6 @@ private:
>>  			 Rectangle *rect);
>>  
>>  	const MediaEntity *entity_;
>> -	int fd_;
>>  };
>>  
>>  } /* namespace libcamera */
>> diff --git a/src/libcamera/include/v4l2_videodevice.h b/src/libcamera/include/v4l2_videodevice.h
>> index 6ecdb64e5f3c..15a83635b9bf 100644
>> --- a/src/libcamera/include/v4l2_videodevice.h
>> +++ b/src/libcamera/include/v4l2_videodevice.h
>> @@ -17,6 +17,7 @@
>>  #include <libcamera/signal.h>
>>  
>>  #include "log.h"
>> +#include "v4l2_device.h"
>>  
>>  namespace libcamera {
>>  
>> @@ -111,7 +112,7 @@ public:
>>  	const std::string toString() const;
>>  };
>>  
>> -class V4L2VideoDevice : protected Loggable
>> +class V4L2VideoDevice : public V4L2Device, protected Loggable
>>  {
>>  public:
>>  	explicit V4L2VideoDevice(const std::string &deviceNode);
>> @@ -122,7 +123,6 @@ public:
>>  	V4L2VideoDevice &operator=(const V4L2VideoDevice &) = delete;
>>  
>>  	int open();
>> -	bool isOpen() const;
>>  	void close();
>>  
>>  	const char *driverName() const { return caps_.driver(); }
>> @@ -167,7 +167,6 @@ private:
>>  	void bufferAvailable(EventNotifier *notifier);
>>  
>>  	std::string deviceNode_;
>> -	int fd_;
>>  	V4L2Capability caps_;
>>  
>>  	enum v4l2_buf_type bufferType_;
>> diff --git a/src/libcamera/meson.build b/src/libcamera/meson.build
>> index 15ab53b1abbe..f26ad5b2dc57 100644
>> --- a/src/libcamera/meson.build
>> +++ b/src/libcamera/meson.build
>> @@ -23,6 +23,7 @@ libcamera_sources = files([
>>      'stream.cpp',
>>      'timer.cpp',
>>      'utils.cpp',
>> +    'v4l2_device.cpp',
>>      'v4l2_subdevice.cpp',
>>      'v4l2_videodevice.cpp',
>>  ])
>> @@ -41,6 +42,7 @@ libcamera_headers = files([
>>      'include/media_object.h',
>>      'include/pipeline_handler.h',
>>      'include/utils.h',
>> +    'include/v4l2_device.h',
>>      'include/v4l2_subdevice.h',
>>      'include/v4l2_videodevice.h',
>>  ])
>> diff --git a/src/libcamera/v4l2_device.cpp b/src/libcamera/v4l2_device.cpp
>> new file mode 100644
>> index 000000000000..f89b2a2982ba
>> --- /dev/null
>> +++ b/src/libcamera/v4l2_device.cpp
>> @@ -0,0 +1,148 @@
>> +/* SPDX-License-Identifier: LGPL-2.1-or-later */
>> +/*
>> + * Copyright (C) 2019, Google Inc.
>> + *
>> + * v4l2_device.cpp - Common base for V4L2 devices and subdevices
>> + */
>> +
>> +#include "v4l2_device.h"
>> +
>> +#include <fcntl.h>
>> +#include <string.h>
>> +#include <sys/ioctl.h>
>> +#include <unistd.h>
>> +
>> +#include "log.h"
>> +
>> +/**
>> + * \file v4l2_device.h
>> + * \brief Common base for V4L2 devices and subdevices
>> + */
>> +
>> +namespace libcamera {
>> +
>> +LOG_DEFINE_CATEGORY(V4L2)
>> +
>> +/**
>> + * \class V4L2Device
>> + * \brief Base class for V4L2Videodev and V4L2Subdev
>> + *
>> + * The V4L2Device class groups together the methods and fields common to
>> + * both V4L2Videodev and V4L2Subdev, and provide a base class which
>> + * provides methods to open and close the device node associated with the
>> + * device and to perform IOCTL system calls on it.
>> + *
>> + * The V4L2Device class cannot be instantiated directly, as its constructor
>> + * is protected. Users should use instead one the derived classes to model
>> + * either a V4L2 video device or a V4L2 subdevice.
>> + */
>> +
>> +/**
>> + * \brief Construct a V4L2Device
>> + *
>> + * The V4L2Device constructor is protected and can only be accessed by the
>> + * V4L2Videodev and V4L2Subdev derived classes.
>> + *
>> + * Initialize the file descriptor to -1.
>> + */
>> +V4L2Device::V4L2Device()
>> +	: fd_(-1)
>> +{
>> +}
>> +
>> +/**
>> + * \fn V4L2Device::fd()
>> + * \brief Retrieve the V4L2 device file descriptor
>> + * \return The V4L2 device file descriptor, -1 if the device node is not open
>> + */
>> +
>> +/**
>> + * \brief Open a V4L2 device node
>> + * \param pathname The filesystem path of the device node to open
>> + * \param flags Access mode flags
>> + *
>> + * Initialize the file descriptor, which was initially set to -1.
>> + *
>> + * \return 0 on success or a negative error code otherwise
>> + */
>> +int V4L2Device::open(const std::string &pathname, unsigned int flags)
>> +{
>> +	if (isOpen()) {
>> +		LOG(V4L2, Error) << "Device already open";
>> +		return -EBUSY;
>> +	}
>> +
>> +	int ret = ::open(pathname.c_str(), flags);
>> +	if (ret < 0) {
>> +		ret = -errno;
>> +		LOG(V4L2, Error) << "Failed to open V4L2 device: "
>> +				 << strerror(-ret);
>> +		return ret;
>> +	}
>> +
>> +	fd_ = ret;
>> +
>> +	return 0;
>> +}
>> +
>> +/**
>> + * \brief Close the device node
>> + *
>> + * Reset the file descriptor to -1
>> + *
>> + * \return 0 on success or a negative error code otherwise
>> + */
>> +int V4L2Device::close()
>> +{
>> +	if (fd_ < 0)
>> +		return 0;
>> +
>> +	int ret = ::close(fd_);
>> +	if (ret < 0) {
>> +		ret = -errno;
>> +		LOG(V4L2, Error) << "Failed to close V4L2 device: "
>> +				 << strerror(-ret);
>> +		return ret;
>> +	}
>> +
>> +	fd_ = -1;
>> +
>> +	return 0;
>> +}
>> +
>> +/**
>> + * \brief Check if the V4L2 device node is open
>> + * \return True if the V4L2 device node is open, false otherwise
>> + */
>> +bool V4L2Device::isOpen() const
>> +{
>> +	return fd_ != -1;
>> +}
>> +
>> +/**
>> + * \brief Perform an IOCTL system call on the device node
>> + * \param request The IOCTL request code
>> + * \param argp A poiunter to the IOCTL argument
> 
> 
> s/poiunter/pointer/
> 
> 
>> + * \return 0 on success or a negative error code otherwise
>> + */
>> +int V4L2Device::ioctl(unsigned long request, void *argp)
>> +{
>> +	/*
>> +	 * Printing out an error message is usually better performed
>> +	 * in the caller, which can provide more context.
>> +	 */
>> +	if (::ioctl(fd_, request, argp) < 0)
>> +		return -errno;
> 
> I /really/ like this ... but note how many of the call sites for
> V4L2Device::ioctl() still work with the -errno fuss, which should now
> just deal directly with 'ret' where it's used.
> 
> 'man ioctl' states:
> 
> RETURN VALUE
>        Usually,  on  success zero is returned.  A few ioctl() requests
>        use the return value as an output parameter and return a
>        nonnegative value on success.  On error, -1 is returned, and
>        errno is set appropriately.
> 
> 
> I really like simplifying the -1, errno check pattern that is
> everywhere. But do we need to be sure we'll never need the return code
> of the ioctl?
> 
> (I don't think we do - and we /could/ have a different call for that if
> necessary)
> 
> 
> 
>> +
>> +	return 0;
>> +}
>> +
>> +/**
>> + * \var V4L2Device::fd_
>> + * \brief The V4L2 device node file descriptor
>> + *
>> + * The file descriptor is initialized to -1 and reset to this value once
>> + * the device node gets closed.
>> + */
>> +
>> +} /* namespace libcamera */
>> diff --git a/src/libcamera/v4l2_subdevice.cpp b/src/libcamera/v4l2_subdevice.cpp
>> index 6681c1920065..b1e5f559b944 100644
>> --- a/src/libcamera/v4l2_subdevice.cpp
>> +++ b/src/libcamera/v4l2_subdevice.cpp
>> @@ -29,7 +29,7 @@
>>  
>>  namespace libcamera {
>>  
>> -LOG_DEFINE_CATEGORY(V4L2Subdev)
>> +LOG_DECLARE_CATEGORY(V4L2)
>>  
>>  /**
>>   * \struct V4L2SubdeviceFormat
>> @@ -102,7 +102,7 @@ const std::string V4L2SubdeviceFormat::toString() const
>>   * path
>>   */
>>  V4L2Subdevice::V4L2Subdevice(const MediaEntity *entity)
>> -	: entity_(entity), fd_(-1)
>> +	: V4L2Device(), entity_(entity)
>>  {
>>  }
>>  
>> @@ -117,45 +117,7 @@ V4L2Subdevice::~V4L2Subdevice()
>>   */
>>  int V4L2Subdevice::open()
>>  {
>> -	int ret;
>> -
>> -	if (isOpen()) {
>> -		LOG(V4L2Subdev, Error) << "Device already open";
>> -		return -EBUSY;
>> -	}
>> -
>> -	ret = ::open(entity_->deviceNode().c_str(), O_RDWR);
>> -	if (ret < 0) {
>> -		ret = -errno;
>> -		LOG(V4L2Subdev, Error)
>> -			<< "Failed to open V4L2 subdevice '"
>> -			<< entity_->deviceNode() << "': " << strerror(-ret);
>> -		return ret;
>> -	}
>> -	fd_ = ret;
>> -
>> -	return 0;
>> -}
>> -
>> -/**
>> - * \brief Check if the subdevice is open
>> - * \return True if the subdevice is open, false otherwise
>> - */
>> -bool V4L2Subdevice::isOpen() const
>> -{
>> -	return fd_ != -1;
>> -}
>> -
>> -/**
>> - * \brief Close the subdevice, releasing any resources acquired by open()
>> - */
>> -void V4L2Subdevice::close()
>> -{
>> -	if (!isOpen())
>> -		return;
>> -
>> -	::close(fd_);
>> -	fd_ = -1;
>> +	return V4L2Device::open(entity_->deviceNode(), O_RDWR);
>>  }
>>  
>>  /**
>> @@ -207,7 +169,7 @@ FormatEnum V4L2Subdevice::formats(unsigned int pad)
>>  	int ret;
>>  
>>  	if (pad >= entity_->pads().size()) {
>> -		LOG(V4L2Subdev, Error) << "Invalid pad: " << pad;
>> +		LOG(V4L2, Error) << "Invalid pad: " << pad;
>>  		return formatMap;
>>  	}
>>  
>> @@ -215,7 +177,7 @@ FormatEnum V4L2Subdevice::formats(unsigned int pad)
>>  	mbusEnum.index = 0;
>>  	mbusEnum.which = V4L2_SUBDEV_FORMAT_ACTIVE;
>>  	while (true) {
>> -		ret = ioctl(fd_, VIDIOC_SUBDEV_ENUM_MBUS_CODE, &mbusEnum);
>> +		ret = ioctl(VIDIOC_SUBDEV_ENUM_MBUS_CODE, &mbusEnum);
>>  		if (ret)
>>  			break;
>>  
>> @@ -229,7 +191,7 @@ FormatEnum V4L2Subdevice::formats(unsigned int pad)
>>  
>>  	if (ret && (errno != EINVAL && errno != ENOTTY)) {
>>  		ret = -errno;
>> -		LOG(V4L2Subdev, Error)
>> +		LOG(V4L2, Error)
>>  			<< "Unable to enumerate formats on pad " << pad
>>  			<< ": " << strerror(-ret);
>>  		formatMap.clear();
>> @@ -250,10 +212,10 @@ int V4L2Subdevice::getFormat(unsigned int pad, V4L2SubdeviceFormat *format)
>>  	subdevFmt.which = V4L2_SUBDEV_FORMAT_ACTIVE;
>>  	subdevFmt.pad = pad;
>>  
>> -	int ret = ioctl(fd_, VIDIOC_SUBDEV_G_FMT, &subdevFmt);
>> +	int ret = ioctl(VIDIOC_SUBDEV_G_FMT, &subdevFmt);
>>  	if (ret) {
>>  		ret = -errno;
>> -		LOG(V4L2Subdev, Error)
>> +		LOG(V4L2, Error)
>>  			<< "Unable to get format on pad " << pad
>>  			<< ": " << strerror(-ret);
>>  		return ret;
>> @@ -286,10 +248,10 @@ int V4L2Subdevice::setFormat(unsigned int pad, V4L2SubdeviceFormat *format)
>>  	subdevFmt.format.height = format->size.height;
>>  	subdevFmt.format.code = format->mbus_code;
>>  
>> -	int ret = ioctl(fd_, VIDIOC_SUBDEV_S_FMT, &subdevFmt);
>> +	int ret = ioctl(VIDIOC_SUBDEV_S_FMT, &subdevFmt);
>>  	if (ret) {
>>  		ret = -errno;
>> -		LOG(V4L2Subdev, Error)
>> +		LOG(V4L2, Error)
>>  			<< "Unable to set format on pad " << pad
>>  			<< ": " << strerror(-ret);
>>  		return ret;
>> @@ -339,7 +301,7 @@ int V4L2Subdevice::enumPadSizes(unsigned int pad,unsigned int code,
>>  	sizeEnum.code = code;
>>  	sizeEnum.which = V4L2_SUBDEV_FORMAT_ACTIVE;
>>  	while (true) {
>> -		ret = ioctl(fd_, VIDIOC_SUBDEV_ENUM_FRAME_SIZE, &sizeEnum);
>> +		ret = ioctl(VIDIOC_SUBDEV_ENUM_FRAME_SIZE, &sizeEnum);
>>  		if (ret)
>>  			break;
>>  
>> @@ -351,7 +313,7 @@ int V4L2Subdevice::enumPadSizes(unsigned int pad,unsigned int code,
>>  
>>  	if (ret && (errno != EINVAL && errno != ENOTTY)) {
>>  		ret = -errno;
>> -		LOG(V4L2Subdev, Error)
>> +		LOG(V4L2, Error)
>>  			<< "Unable to enumerate sizes on pad " << pad
>>  			<< ": " << strerror(-ret);
>>  		sizes->clear();
>> @@ -377,10 +339,10 @@ int V4L2Subdevice::setSelection(unsigned int pad, unsigned int target,
>>  	sel.r.width = rect->w;
>>  	sel.r.height = rect->h;
>>  
>> -	int ret = ioctl(fd_, VIDIOC_SUBDEV_S_SELECTION, &sel);
>> +	int ret = ioctl(VIDIOC_SUBDEV_S_SELECTION, &sel);
>>  	if (ret < 0) {
>>  		ret = -errno;
>> -		LOG(V4L2Subdev, Error)
>> +		LOG(V4L2, Error)
>>  			<< "Unable to set rectangle " << target << " on pad "
>>  			<< pad << ": " << strerror(-ret);
>>  		return ret;
>> diff --git a/src/libcamera/v4l2_videodevice.cpp b/src/libcamera/v4l2_videodevice.cpp
>> index 8957cf8f97d3..14e711d5dde3 100644
>> --- a/src/libcamera/v4l2_videodevice.cpp
>> +++ b/src/libcamera/v4l2_videodevice.cpp
>> @@ -30,7 +30,7 @@
>>   */
>>  namespace libcamera {
>>  
>> -LOG_DEFINE_CATEGORY(V4L2)
>> +LOG_DECLARE_CATEGORY(V4L2)
>>  
>>  /**
>>   * \struct V4L2Capability
>> @@ -270,7 +270,7 @@ const std::string V4L2DeviceFormat::toString() const
>>   * \param[in] deviceNode The file-system path to the video device node
>>   */
>>  V4L2VideoDevice::V4L2VideoDevice(const std::string &deviceNode)
>> -	: deviceNode_(deviceNode), fd_(-1), bufferPool_(nullptr),
>> +	: V4L2Device(), deviceNode_(deviceNode), bufferPool_(nullptr),
>>  	  queuedBuffersCount_(0), fdEvent_(nullptr)
>>  {
>>  	/*
>> @@ -305,21 +305,11 @@ int V4L2VideoDevice::open()
>>  {
>>  	int ret;
>>  
>> -	if (isOpen()) {
>> -		LOG(V4L2, Error) << "Device already open";
>> -		return -EBUSY;
>> -	}
>> -
>> -	ret = ::open(deviceNode_.c_str(), O_RDWR | O_NONBLOCK);
>> -	if (ret < 0) {
>> -		ret = -errno;
>> -		LOG(V4L2, Error)
>> -			<< "Failed to open V4L2 device: " << strerror(-ret);
>> +	ret = V4L2Device::open(deviceNode_, O_RDWR | O_NONBLOCK);
>> +	if (ret < 0)
>>  		return ret;
>> -	}
>> -	fd_ = ret;
>>  
>> -	ret = ioctl(fd_, VIDIOC_QUERYCAP, &caps_);
>> +	ret = ioctl(VIDIOC_QUERYCAP, &caps_);
>>  	if (ret < 0) {
>>  		ret = -errno;
>>  		LOG(V4L2, Error)
>> @@ -342,20 +332,20 @@ int V4L2VideoDevice::open()
>>  	 * (POLLIN), and write notifications for OUTPUT devices (POLLOUT).
>>  	 */
>>  	if (caps_.isVideoCapture()) {
>> -		fdEvent_ = new EventNotifier(fd_, EventNotifier::Read);
>> +		fdEvent_ = new EventNotifier(fd(), EventNotifier::Read);
>>  		bufferType_ = caps_.isMultiplanar()
>>  			    ? V4L2_BUF_TYPE_VIDEO_CAPTURE_MPLANE
>>  			    : V4L2_BUF_TYPE_VIDEO_CAPTURE;
>>  	} else if (caps_.isVideoOutput()) {
>> -		fdEvent_ = new EventNotifier(fd_, EventNotifier::Write);
>> +		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);
>> +		fdEvent_ = new EventNotifier(fd(), EventNotifier::Read);
>>  		bufferType_ = V4L2_BUF_TYPE_META_CAPTURE;
>>  	} else if (caps_.isMetaOutput()) {
>> -		fdEvent_ = new EventNotifier(fd_, EventNotifier::Write);
>> +		fdEvent_ = new EventNotifier(fd(), EventNotifier::Write);
>>  		bufferType_ = V4L2_BUF_TYPE_META_OUTPUT;
>>  	} else {
>>  		LOG(V4L2, Error) << "Device is not a supported type";
>> @@ -368,28 +358,16 @@ int V4L2VideoDevice::open()
>>  	return 0;
>>  }
>>  
>> -/**
>> - * \brief Check if device is successfully opened
>> - * \return True if the device is open, false otherwise
>> - */
>> -bool V4L2VideoDevice::isOpen() const
>> -{
>> -	return fd_ != -1;
>> -}
>> -
>>  /**
>>   * \brief Close the device, releasing any resources acquired by open()
>>   */
>>  void V4L2VideoDevice::close()
>>  {
>> -	if (fd_ < 0)
>> +	if (fd() < 0)
>>  		return;
>>  
>>  	releaseBuffers();
>>  	delete fdEvent_;
>> -
>> -	::close(fd_);
>> -	fd_ = -1;
>>  }
>>  
>>  /**
>> @@ -462,7 +440,7 @@ int V4L2VideoDevice::getFormatMeta(V4L2DeviceFormat *format)
>>  	int ret;
>>  
>>  	v4l2Format.type = bufferType_;
>> -	ret = ioctl(fd_, VIDIOC_G_FMT, &v4l2Format);
>> +	ret = ioctl(VIDIOC_G_FMT, &v4l2Format);
> 
> 
> I really like that ioctl now knows about the FD internally and thus is
> simpler :)
> 
> "do this action with this structure..."
> 
> 
>>  	if (ret) {
>>  		ret = -errno;
>>  		LOG(V4L2, Error) << "Unable to get format: " << strerror(-ret);
> 
> This is an example of things that I think should now be:
> 
> ret = ioctl(VIDIOC_G_FMT, &v4l2Format);
> if (ret) {
> 	LOG(V4L2, Error) << "Unable to get format: " << strerror(ret);
> 	...
> }
> 
> That probably applies to all uses of V4L2Device::ioctl()
> 
> 
>> @@ -488,7 +466,7 @@ int V4L2VideoDevice::setFormatMeta(V4L2DeviceFormat *format)
>>  	v4l2Format.type = bufferType_;
>>  	pix->dataformat = format->fourcc;
>>  	pix->buffersize = format->planes[0].size;
>> -	ret = ioctl(fd_, VIDIOC_S_FMT, &v4l2Format);
>> +	ret = ioctl(VIDIOC_S_FMT, &v4l2Format);
>>  	if (ret) {
>>  		ret = -errno;
>>  		LOG(V4L2, Error) << "Unable to set format: " << strerror(-ret);
>> @@ -516,7 +494,7 @@ int V4L2VideoDevice::getFormatMultiplane(V4L2DeviceFormat *format)
>>  	int ret;
>>  
>>  	v4l2Format.type = bufferType_;
>> -	ret = ioctl(fd_, VIDIOC_G_FMT, &v4l2Format);
>> +	ret = ioctl(VIDIOC_G_FMT, &v4l2Format);
>>  	if (ret) {
>>  		ret = -errno;
>>  		LOG(V4L2, Error) << "Unable to get format: " << strerror(-ret);
>> @@ -554,7 +532,7 @@ int V4L2VideoDevice::setFormatMultiplane(V4L2DeviceFormat *format)
>>  		pix->plane_fmt[i].sizeimage = format->planes[i].size;
>>  	}
>>  
>> -	ret = ioctl(fd_, VIDIOC_S_FMT, &v4l2Format);
>> +	ret = ioctl(VIDIOC_S_FMT, &v4l2Format);
>>  	if (ret) {
>>  		ret = -errno;
>>  		LOG(V4L2, Error) << "Unable to set format: " << strerror(-ret);
>> @@ -584,7 +562,7 @@ int V4L2VideoDevice::getFormatSingleplane(V4L2DeviceFormat *format)
>>  	int ret;
>>  
>>  	v4l2Format.type = bufferType_;
>> -	ret = ioctl(fd_, VIDIOC_G_FMT, &v4l2Format);
>> +	ret = ioctl(VIDIOC_G_FMT, &v4l2Format);
>>  	if (ret) {
>>  		ret = -errno;
>>  		LOG(V4L2, Error) << "Unable to get format: " << strerror(-ret);
>> @@ -613,7 +591,7 @@ int V4L2VideoDevice::setFormatSingleplane(V4L2DeviceFormat *format)
>>  	pix->pixelformat = format->fourcc;
>>  	pix->bytesperline = format->planes[0].bpl;
>>  	pix->field = V4L2_FIELD_NONE;
>> -	ret = ioctl(fd_, VIDIOC_S_FMT, &v4l2Format);
>> +	ret = ioctl(VIDIOC_S_FMT, &v4l2Format);
>>  	if (ret) {
>>  		ret = -errno;
>>  		LOG(V4L2, Error) << "Unable to set format: " << strerror(-ret);
>> @@ -643,7 +621,7 @@ int V4L2VideoDevice::requestBuffers(unsigned int count)
>>  	rb.type = bufferType_;
>>  	rb.memory = memoryType_;
>>  
>> -	ret = ioctl(fd_, VIDIOC_REQBUFS, &rb);
>> +	ret = ioctl(VIDIOC_REQBUFS, &rb);
>>  	if (ret < 0) {
>>  		ret = -errno;
>>  		LOG(V4L2, Error)
>> @@ -695,7 +673,7 @@ int V4L2VideoDevice::exportBuffers(BufferPool *pool)
>>  		buf.length = VIDEO_MAX_PLANES;
>>  		buf.m.planes = planes;
>>  
>> -		ret = ioctl(fd_, VIDIOC_QUERYBUF, &buf);
>> +		ret = ioctl(VIDIOC_QUERYBUF, &buf);
>>  		if (ret < 0) {
>>  			ret = -errno;
>>  			LOG(V4L2, Error)
>> @@ -748,7 +726,7 @@ int V4L2VideoDevice::createPlane(Buffer *buffer, unsigned int planeIndex,
>>  	expbuf.plane = planeIndex;
>>  	expbuf.flags = O_RDWR;
>>  
>> -	ret = ioctl(fd_, VIDIOC_EXPBUF, &expbuf);
>> +	ret = ioctl(VIDIOC_EXPBUF, &expbuf);
>>  	if (ret < 0) {
>>  		ret = -errno;
>>  		LOG(V4L2, Error)
>> @@ -855,7 +833,7 @@ int V4L2VideoDevice::queueBuffer(Buffer *buffer)
>>  
>>  	LOG(V4L2, Debug) << "Queueing buffer " << buf.index;
>>  
>> -	ret = ioctl(fd_, VIDIOC_QBUF, &buf);
>> +	ret = ioctl(VIDIOC_QBUF, &buf);
>>  	if (ret < 0) {
>>  		ret = -errno;
>>  		LOG(V4L2, Error)
>> @@ -892,7 +870,7 @@ Buffer *V4L2VideoDevice::dequeueBuffer()
>>  		buf.m.planes = planes;
>>  	}
>>  
>> -	ret = ioctl(fd_, VIDIOC_DQBUF, &buf);
>> +	ret = ioctl(VIDIOC_DQBUF, &buf);
>>  	if (ret < 0) {
>>  		ret = -errno;
>>  		LOG(V4L2, Error)
>> @@ -952,7 +930,7 @@ int V4L2VideoDevice::streamOn()
>>  {
>>  	int ret;
>>  
>> -	ret = ioctl(fd_, VIDIOC_STREAMON, &bufferType_);
>> +	ret = ioctl(VIDIOC_STREAMON, &bufferType_);
>>  	if (ret < 0) {
>>  		ret = -errno;
>>  		LOG(V4L2, Error)
>> @@ -975,7 +953,7 @@ int V4L2VideoDevice::streamOff()
>>  {
>>  	int ret;
>>  
>> -	ret = ioctl(fd_, VIDIOC_STREAMOFF, &bufferType_);
>> +	ret = ioctl(VIDIOC_STREAMOFF, &bufferType_);
>>  	if (ret < 0) {
>>  		ret = -errno;
>>  		LOG(V4L2, Error)
>>
>

Hi Kieran,

On Wed, Jun 12, 2019 at 02:50:44PM +0100, Kieran Bingham wrote:
> Hi Jacopo,
>
> On 12/06/2019 14:38, Jacopo Mondi wrote:
> > he V4L2 devices and subdevices share a few common operations,like
>
> s/he/The/
>
> > opening and closing a device node, and perform IOCTLs on the device.
> >
> > With the forthcoming introduction of support for V4L2 controls, the
> > quantity of shared code will drastically increase, as the control
> > implementation is identical for the two.
> >
> > To maximize code re-use and avoid duplications, provide a V4L2Device
> > base class which groups the common operations and members.
> >
> > The newly introduced base class provides methods to open/close a device
> > node, access the file descriptor, and perform IOCTLs on the device.
> >
> > Signed-off-by: Jacopo Mondi <jacopo@jmondi.org>
> > Signed-off-by: Kieran Bingham <kieran.bingham@ideasonboard.com>
>
>
> Thank you - this is much easier to review now :-D
>
>
> A few comments below:
>
> > ---
> >  src/libcamera/include/v4l2_device.h      |  36 ++++++
> >  src/libcamera/include/v4l2_subdevice.h   |   6 +-
> >  src/libcamera/include/v4l2_videodevice.h |   5 +-
> >  src/libcamera/meson.build                |   2 +
> >  src/libcamera/v4l2_device.cpp            | 148 +++++++++++++++++++++++
> >  src/libcamera/v4l2_subdevice.cpp         |  66 +++-------
> >  src/libcamera/v4l2_videodevice.cpp       |  68 ++++-------
> >  7 files changed, 227 insertions(+), 104 deletions(-)
> >  create mode 100644 src/libcamera/include/v4l2_device.h
> >  create mode 100644 src/libcamera/v4l2_device.cpp
> >
>

[snip]

> > + * \return 0 on success or a negative error code otherwise
> > + */
> > +int V4L2Device::ioctl(unsigned long request, void *argp)
> > +{
> > +	/*
> > +	 * Printing out an error message is usually better performed
> > +	 * in the caller, which can provide more context.
> > +	 */
> > +	if (::ioctl(fd_, request, argp) < 0)
> > +		return -errno;
>
> I /really/ like this ... but note how many of the call sites for
> V4L2Device::ioctl() still work with the -errno fuss, which should now
> just deal directly with 'ret' where it's used.
>
> 'man ioctl' states:
>
> RETURN VALUE
>        Usually,  on  success zero is returned.  A few ioctl() requests
>        use the return value as an output parameter and return a
>        nonnegative value on success.  On error, -1 is returned, and
>        errno is set appropriately.
>
>
> I really like simplifying the -1, errno check pattern that is
> everywhere. But do we need to be sure we'll never need the return code
> of the ioctl?
>
> (I don't think we do - and we /could/ have a different call for that if
> necessary)
>

I agree, I think we're safe if we check for < 0 as it is done now.

>
>
> > +
> > +	return 0;
> > +}
> >

[snip]

> >  /**
> > @@ -462,7 +440,7 @@ int V4L2VideoDevice::getFormatMeta(V4L2DeviceFormat *format)
> >  	int ret;
> >
> >  	v4l2Format.type = bufferType_;
> > -	ret = ioctl(fd_, VIDIOC_G_FMT, &v4l2Format);
> > +	ret = ioctl(VIDIOC_G_FMT, &v4l2Format);
>
>
> I really like that ioctl now knows about the FD internally and thus is
> simpler :)
>
> "do this action with this structure..."
>
>
> >  	if (ret) {
> >  		ret = -errno;
> >  		LOG(V4L2, Error) << "Unable to get format: " << strerror(-ret);
>
> This is an example of things that I think should now be:
>
> ret = ioctl(VIDIOC_G_FMT, &v4l2Format);
> if (ret) {
> 	LOG(V4L2, Error) << "Unable to get format: " << strerror(ret);
> 	...
> }
>
> That probably applies to all uses of V4L2Device::ioctl()

Yes indeed. I'll fix and resend.

Thanks
   j