[{"id":28970,"web_url":"https://patchwork.libcamera.org/comment/28970/","msgid":"<171046290174.1913896.11420169574014023828@ping.linuxembedded.co.uk>","date":"2024-03-15T00:35:01","subject":"Re: [PATCH v2 03/14] libcamera: v4l2_subdevice: Expose media bus\n\tformat info as internal API","submitter":{"id":4,"url":"https://patchwork.libcamera.org/api/people/4/","name":"Kieran Bingham","email":"kieran.bingham@ideasonboard.com"},"content":"Quoting Laurent Pinchart (2024-03-15 00:16:02)\n> The V4L2SubdeviceFormatInfo structure, internal to the\n> v4l2_subdevice.cpp compilation unit, contains information about media\n> bus formats that will be useful in other parts of libcamera. To prepare\n> for this, expose the structure in the v4l2_subdevice.h header and turn\n> it into a class with a similar design as PixelFormatInfo.\n> \n> Signed-off-by: Laurent Pinchart \n> Reviewed-by: Jacopo Mondi \n> ---\n> Changes since v1:\n> \n> - Improve MediaBusFormatInfo::code documentation\n\nLGTM\n\n\nReviewed-by: Kieran Bingham \n\n> ---\n> include/libcamera/internal/v4l2_subdevice.h | 13 +++\n> src/libcamera/v4l2_subdevice.cpp | 94 ++++++++++++++-------\n> 2 files changed, 76 insertions(+), 31 deletions(-)\n> \n> diff --git a/include/libcamera/internal/v4l2_subdevice.h b/include/libcamera/internal/v4l2_subdevice.h\n> index 17db311bcfb3..a4df9ddfd322 100644\n> --- a/include/libcamera/internal/v4l2_subdevice.h\n> +++ b/include/libcamera/internal/v4l2_subdevice.h\n> @@ -29,6 +29,19 @@ namespace libcamera {\n> \n> class MediaDevice;\n> \n> +class MediaBusFormatInfo\n> +{\n> +public:\n> + bool isValid() const { return code != 0; }\n> +\n> + static const MediaBusFormatInfo &info(uint32_t code);\n> +\n> + const char *name;\n> + uint32_t code;\n> + unsigned int bitsPerPixel;\n> + PixelFormatInfo::ColourEncoding colourEncoding;\n> +};\n> +\n> struct V4L2SubdeviceCapability final : v4l2_subdev_capability {\n> bool isReadOnly() const\n> {\n> diff --git a/src/libcamera/v4l2_subdevice.cpp b/src/libcamera/v4l2_subdevice.cpp\n> index 1286e7c385c4..4918e28e5f18 100644\n> --- a/src/libcamera/v4l2_subdevice.cpp\n> +++ b/src/libcamera/v4l2_subdevice.cpp\n> @@ -36,28 +36,40 @@ namespace libcamera {\n> \n> LOG_DECLARE_CATEGORY(V4L2)\n> \n> +/**\n> + * \\class MediaBusFormatInfo\n> + * \\brief Information about media bus formats\n> + *\n> + * The MediaBusFormatInfo class groups together information describing a media\n> + * bus format. It facilitates handling of media bus formats by providing data\n> + * commonly used in pipeline handlers.\n> + *\n> + * \\var MediaBusFormatInfo::name\n> + * \\brief The format name as a human-readable string, used as the text\n> + * representation of the format\n> + *\n> + * \\var MediaBusFormatInfo::code\n> + * \\brief The media bus format code described by this instance (MEDIA_BUS_FMT_*)\n> + *\n> + * \\var MediaBusFormatInfo::bitsPerPixel\n> + * \\brief The average number of bits per pixel\n> + *\n> + * The number of bits per pixel averages the total number of bits for all\n> + * colour components over the whole image, excluding any padding bits or\n> + * padding pixels.\n> + *\n> + * For formats that transmit multiple or fractional pixels per sample, the\n> + * value will differ from the bus width.\n> + *\n> + * Formats that don't have a fixed number of bits per pixel, such as compressed\n> + * formats, report 0 in this field.\n> + *\n> + * \\var MediaBusFormatInfo::colourEncoding\n> + * \\brief The colour encoding type\n> + */\n> +\n> namespace {\n> \n> -/*\n> - * \\struct MediaBusFormatInfo\n> - * \\brief Information about media bus formats\n> - * \\param name Name of MBUS format\n> - * \\param code The media bus format code\n> - * \\param bitsPerPixel Bits per pixel\n> - * \\param colourEncoding Type of colour encoding\n> - */\n> -struct MediaBusFormatInfo {\n> - const char *name;\n> - uint32_t code;\n> - unsigned int bitsPerPixel;\n> - PixelFormatInfo::ColourEncoding colourEncoding;\n> -};\n> -\n> -/*\n> - * \\var mediaBusFormatInfo\n> - * \\brief A map that associates MediaBusFormatInfo struct to V4L2 media\n> - * bus codes\n> - */\n> const std::map mediaBusFormatInfo{\n> /* This table is sorted to match the order in linux/media-bus-format.h */\n> { MEDIA_BUS_FMT_RGB444_2X8_PADHI_BE, {\n> @@ -557,6 +569,33 @@ const std::map mediaBusFormatInfo{\n> \n> } /* namespace */\n> \n> +/**\n> + * \\fn bool MediaBusFormatInfo::isValid() const\n> + * \\brief Check if the media bus format info is valid\n> + * \\return True if the media bus format info is valid, false otherwise\n> + */\n> +\n> +/**\n> + * \\brief Retrieve information about a media bus format\n> + * \\param[in] code The media bus format code\n> + * \\return The MediaBusFormatInfo describing the \\a code if known, or an invalid\n> + * MediaBusFormatInfo otherwise\n> + */\n> +const MediaBusFormatInfo &MediaBusFormatInfo::info(uint32_t code)\n> +{\n> + static const MediaBusFormatInfo invalid{};\n> +\n> + const auto it = mediaBusFormatInfo.find(code);\n> + if (it == mediaBusFormatInfo.end()) {\n> + LOG(V4L2, Warning)\n> + << \"Unsupported media bus format \"\n> + << utils::hex(code, 4);\n> + return invalid;\n> + }\n> +\n> + return it->second;\n> +}\n> +\n> /**\n> * \\struct V4L2SubdeviceCapability\n> * \\brief struct v4l2_subdev_capability object wrapper and helpers\n> @@ -653,14 +692,7 @@ const std::string V4L2SubdeviceFormat::toString() const\n> */\n> uint8_t V4L2SubdeviceFormat::bitsPerPixel() const\n> {\n> - const auto it = mediaBusFormatInfo.find(mbus_code);\n> - if (it == mediaBusFormatInfo.end()) {\n> - LOG(V4L2, Error) << \"No information available for format '\"\n> - << *this << \"'\";\n> - return 0;\n> - }\n> -\n> - return it->second.bitsPerPixel;\n> + return MediaBusFormatInfo::info(mbus_code).bitsPerPixel;\n> }\n> \n> /**\n> @@ -927,9 +959,9 @@ std::optional V4L2Subdevice::toColorSpace(const v4l2_mbus_framefmt &\n> return std::nullopt;\n> \n> PixelFormatInfo::ColourEncoding colourEncoding;\n> - auto iter = mediaBusFormatInfo.find(format.code);\n> - if (iter != mediaBusFormatInfo.end()) {\n> - colourEncoding = iter->second.colourEncoding;\n> + const MediaBusFormatInfo &info = MediaBusFormatInfo::info(format.code);\n> + if (info.isValid()) {\n> + colourEncoding = info.colourEncoding;\n> } else {\n> LOG(V4L2, Warning)\n> << \"Unknown subdev format \"\n> -- \n> Regards,\n> \n> Laurent Pinchart\n>","headers":{"Return-Path":"","X-Original-To":"parsemail@patchwork.libcamera.org","Delivered-To":"parsemail@patchwork.libcamera.org","Received":["from lancelot.ideasonboard.com (lancelot.ideasonboard.com\n\t[92.243.16.209])\n\tby patchwork.libcamera.org (Postfix) with ESMTPS id 51E09BD808\n\tfor ;\n\tFri, 15 Mar 2024 00:35:06 +0000 (UTC)","from lancelot.ideasonboard.com (localhost [IPv6:::1])\n\tby lancelot.ideasonboard.com (Postfix) with ESMTP id B929362C91;\n\tFri, 15 Mar 2024 01:35:05 +0100 (CET)","from perceval.ideasonboard.com (perceval.ideasonboard.com\n\t[IPv6:2001:4b98:dc2:55:216:3eff:fef7:d647])\n\tby lancelot.ideasonboard.com (Postfix) with ESMTPS id A035B62C87\n\tfor ;\n\tFri, 15 Mar 2024 01:35:04 +0100 (CET)","from pendragon.ideasonboard.com\n\t(aztw-30-b2-v4wan-166917-cust845.vm26.cable.virginm.net\n\t[82.37.23.78])\n\tby perceval.ideasonboard.com (Postfix) with ESMTPSA id E8946667;\n\tFri, 15 Mar 2024 01:34:40 +0100 (CET)"],"Authentication-Results":"lancelot.ideasonboard.com; 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