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Subject: Re: [RFC PATCH 18/20] lib: image-formats: Add v4l2 formats support
From:   Hans Verkuil <hverkuil@xs4all.nl>
To:     Maxime Ripard <maxime.ripard@bootlin.com>,
        Daniel Vetter <daniel.vetter@intel.com>,
        David Airlie <airlied@linux.ie>,
        Maarten Lankhorst <maarten.lankhorst@linux.intel.com>,
        Sean Paul <seanpaul@chromium.org>,
        Mauro Carvalho Chehab <mchehab@kernel.org>
Cc:     Sakari Ailus <sakari.ailus@linux.intel.com>,
        Hans Verkuil <hans.verkuil@cisco.com>,
        Laurent Pinchart <laurent.pinchart@ideasonboard.com>,
        Thomas Petazzoni <thomas.petazzoni@bootlin.com>,
        Paul Kocialkowski <paul.kocialkowski@bootlin.com>,
        dri-devel@lists.freedesktop.org, linux-kernel@vger.kernel.org,
        linux-media@vger.kernel.org
References: <cover.92acdec88ee4c280cb74e08ea22f0075e5fa055c.1553032382.git-series.maxime.ripard@bootlin.com>
 <c97024b97d3261dcf41aad3c8bc1c5d9906f33c9.1553032382.git-series.maxime.ripard@bootlin.com>
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Date:   Thu, 11 Apr 2019 09:15:50 +0200
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On 4/11/19 9:12 AM, Hans Verkuil wrote:
> Hi Maxime,
> 
> Some comments below...
> 
> On 3/19/19 10:57 PM, Maxime Ripard wrote:
>> V4L2 uses different fourcc's than DRM, and has a different set of formats.
>> For now, let's add the v4l2 fourcc's for the already existing formats.
>>
>> Signed-off-by: Maxime Ripard <maxime.ripard@bootlin.com>
>> ---
>>  include/linux/image-formats.h |  9 +++++-
>>  lib/image-formats.c           | 67 ++++++++++++++++++++++++++++++++++++-
>>  2 files changed, 76 insertions(+)
>>
>> diff --git a/include/linux/image-formats.h b/include/linux/image-formats.h
>> index 53fd73a71b3d..fbc3a4501ebd 100644
>> --- a/include/linux/image-formats.h
>> +++ b/include/linux/image-formats.h
>> @@ -26,6 +26,13 @@ struct image_format_info {
>>  	};
>>  
>>  	/**
>> +	 * @v4l2_fmt:
>> +	 *
>> +	 * V4L2 4CC format identifier (V4L2_PIX_FMT_*)
>> +	 */
>> +	u32 v4l2_fmt;
>> +
>> +	/**
>>  	 * @depth:
>>  	 *
>>  	 * Color depth (number of bits per pixel excluding padding bits),
>> @@ -222,6 +229,8 @@ image_format_info_is_yuv_sampling_444(const struct image_format_info *info)
>>  
>>  const struct image_format_info *__image_format_drm_lookup(u32 drm);
>>  const struct image_format_info *image_format_drm_lookup(u32 drm);
>> +const struct image_format_info *__image_format_v4l2_lookup(u32 v4l2);
>> +const struct image_format_info *image_format_v4l2_lookup(u32 v4l2);
>>  unsigned int image_format_plane_cpp(const struct image_format_info *format,
>>  				    int plane);
>>  unsigned int image_format_plane_width(int width,
>> diff --git a/lib/image-formats.c b/lib/image-formats.c
>> index 9b9a73220c5d..39f1d38ae861 100644
>> --- a/lib/image-formats.c
>> +++ b/lib/image-formats.c
>> @@ -8,6 +8,7 @@
>>  static const struct image_format_info formats[] = {
>>  	{
>>  		.drm_fmt = DRM_FORMAT_C8,
>> +		.v4l2_fmt = V4L2_PIX_FMT_GREY,
>>  		.depth = 8,
>>  		.num_planes = 1,
>>  		.cpp = { 1, 0, 0 },
>> @@ -15,6 +16,7 @@ static const struct image_format_info formats[] = {
>>  		.vsub = 1,
>>  	}, {
>>  		.drm_fmt = DRM_FORMAT_RGB332,
>> +		.v4l2_fmt = V4L2_PIX_FMT_RGB332,
>>  		.depth = 8,
>>  		.num_planes = 1,
>>  		.cpp = { 1, 0, 0 },
>> @@ -29,6 +31,7 @@ static const struct image_format_info formats[] = {
>>  		.vsub = 1,
>>  	}, {
>>  		.drm_fmt = DRM_FORMAT_XRGB4444,
>> +		.v4l2_fmt = V4L2_PIX_FMT_XRGB444,
>>  		.depth = 0,
>>  		.num_planes = 1,
>>  		.cpp = { 2, 0, 0 },
>> @@ -57,6 +60,7 @@ static const struct image_format_info formats[] = {
>>  		.vsub = 1,
>>  	}, {
>>  		.drm_fmt = DRM_FORMAT_ARGB4444,
>> +		.v4l2_fmt = V4L2_PIX_FMT_ARGB444,
>>  		.depth = 0,
>>  		.num_planes = 1,
>>  		.cpp = { 2, 0, 0 },
>> @@ -89,6 +93,7 @@ static const struct image_format_info formats[] = {
>>  		.has_alpha = true,
>>  	}, {
>>  		.drm_fmt = DRM_FORMAT_XRGB1555,
>> +		.v4l2_fmt = V4L2_PIX_FMT_XRGB555,
>>  		.depth = 15,
>>  		.num_planes = 1,
>>  		.cpp = { 2, 0, 0 },
>> @@ -117,6 +122,7 @@ static const struct image_format_info formats[] = {
>>  		.vsub = 1,
>>  	}, {
>>  		.drm_fmt = DRM_FORMAT_ARGB1555,
>> +		.v4l2_fmt = V4L2_PIX_FMT_ARGB555,
>>  		.depth = 15,
>>  		.num_planes = 1,
>>  		.cpp = { 2, 0, 0 },
>> @@ -149,6 +155,7 @@ static const struct image_format_info formats[] = {
>>  		.has_alpha = true,
>>  	}, {
>>  		.drm_fmt = DRM_FORMAT_RGB565,
>> +		.v4l2_fmt = V4L2_PIX_FMT_RGB565,
>>  		.depth = 16,
>>  		.num_planes = 1,
>>  		.cpp = { 2, 0, 0 },
>> @@ -163,6 +170,7 @@ static const struct image_format_info formats[] = {
>>  		.vsub = 1,
>>  	}, {
>>  		.drm_fmt = DRM_FORMAT_RGB888,
>> +		.v4l2_fmt = V4L2_PIX_FMT_RGB24,
> 
> The V4L2 pixelformats describe the order of the components in memory, and as
> such are independent of the CPU endianness. How is that for the DRM formats?
> 
> Will the order of DRM_FORMAT_RGB888 in memory differ between little and big
> endian systems?
> 
> Mind you, V4L2 drivers are frankly never tested on big endian systems and I
> suspect many if not all will fail miserably on details like this.

Never mind, I now see that there was a long discussion about this same topic.

	Hans

> 
>>  		.depth = 24,
>>  		.num_planes = 1,
>>  		.cpp = { 3, 0, 0 },
>> @@ -170,6 +178,7 @@ static const struct image_format_info formats[] = {
>>  		.vsub = 1,
>>  	}, {
>>  		.drm_fmt = DRM_FORMAT_BGR888,
>> +		.v4l2_fmt = V4L2_PIX_FMT_BGR24,
>>  		.depth = 24,
>>  		.num_planes = 1,
>>  		.cpp = { 3, 0, 0 },
>> @@ -177,6 +186,7 @@ static const struct image_format_info formats[] = {
>>  		.vsub = 1,
>>  	}, {
>>  		.drm_fmt = DRM_FORMAT_XRGB8888,
>> +		.v4l2_fmt = V4L2_PIX_FMT_XRGB32,
>>  		.depth = 24,
>>  		.num_planes = 1,
>>  		.cpp = { 4, 0, 0 },
>> @@ -281,6 +291,7 @@ static const struct image_format_info formats[] = {
>>  		.has_alpha = true,
>>  	}, {
>>  		.drm_fmt = DRM_FORMAT_ARGB8888,
>> +		.v4l2_fmt = V4L2_PIX_FMT_ARGB32,
>>  		.depth = 32,
>>  		.num_planes = 1,
>>  		.cpp = { 4, 0, 0 },
>> @@ -361,6 +372,7 @@ static const struct image_format_info formats[] = {
>>  		.has_alpha = true,
>>  	}, {
>>  		.drm_fmt = DRM_FORMAT_YUV410,
>> +		.v4l2_fmt = V4L2_PIX_FMT_YUV410,
>>  		.depth = 0,
>>  		.num_planes = 3,
>>  		.cpp = { 1, 1, 1 },
>> @@ -369,6 +381,7 @@ static const struct image_format_info formats[] = {
>>  		.is_yuv = true,
>>  	}, {
>>  		.drm_fmt = DRM_FORMAT_YVU410,
>> +		.v4l2_fmt = V4L2_PIX_FMT_YVU410,
>>  		.depth = 0,
>>  		.num_planes = 3,
>>  		.cpp = { 1, 1, 1 },
>> @@ -393,6 +406,7 @@ static const struct image_format_info formats[] = {
>>  		.is_yuv = true,
>>  	}, {
>>  		.drm_fmt = DRM_FORMAT_YUV420,
>> +		.v4l2_fmt = V4L2_PIX_FMT_YUV420M,
>>  		.depth = 0,
>>  		.num_planes = 3,
>>  		.cpp = { 1, 1, 1 },
>> @@ -401,6 +415,7 @@ static const struct image_format_info formats[] = {
>>  		.is_yuv = true,
>>  	}, {
>>  		.drm_fmt = DRM_FORMAT_YVU420,
>> +		.v4l2_fmt = V4L2_PIX_FMT_YVU420M,
>>  		.depth = 0,
>>  		.num_planes = 3,
>>  		.cpp = { 1, 1, 1 },
>> @@ -409,6 +424,7 @@ static const struct image_format_info formats[] = {
>>  		.is_yuv = true,
>>  	}, {
>>  		.drm_fmt = DRM_FORMAT_YUV422,
>> +		.v4l2_fmt = V4L2_PIX_FMT_YUV422M,
>>  		.depth = 0,
>>  		.num_planes = 3,
>>  		.cpp = { 1, 1, 1 },
>> @@ -417,6 +433,7 @@ static const struct image_format_info formats[] = {
>>  		.is_yuv = true,
>>  	}, {
>>  		.drm_fmt = DRM_FORMAT_YVU422,
>> +		.v4l2_fmt = V4L2_PIX_FMT_YVU422M,
>>  		.depth = 0,
>>  		.num_planes = 3,
>>  		.cpp = { 1, 1, 1 },
>> @@ -425,6 +442,7 @@ static const struct image_format_info formats[] = {
>>  		.is_yuv = true,
>>  	}, {
>>  		.drm_fmt = DRM_FORMAT_YUV444,
>> +		.v4l2_fmt = V4L2_PIX_FMT_YUV444M,
>>  		.depth = 0,
>>  		.num_planes = 3,
>>  		.cpp = { 1, 1, 1 },
>> @@ -433,6 +451,7 @@ static const struct image_format_info formats[] = {
>>  		.is_yuv = true,
>>  	}, {
>>  		.drm_fmt = DRM_FORMAT_YVU444,
>> +		.v4l2_fmt = V4L2_PIX_FMT_YVU444M,
>>  		.depth = 0,
>>  		.num_planes = 3,
>>  		.cpp = { 1, 1, 1 },
>> @@ -441,6 +460,7 @@ static const struct image_format_info formats[] = {
>>  		.is_yuv = true,
>>  	}, {
>>  		.drm_fmt = DRM_FORMAT_NV12,
>> +		.v4l2_fmt = V4L2_PIX_FMT_NV12,
>>  		.depth = 0,
>>  		.num_planes = 2,
>>  		.cpp = { 1, 2, 0 },
>> @@ -449,6 +469,7 @@ static const struct image_format_info formats[] = {
>>  		.is_yuv = true,
>>  	}, {
>>  		.drm_fmt = DRM_FORMAT_NV21,
>> +		.v4l2_fmt = V4L2_PIX_FMT_NV21,
>>  		.depth = 0,
>>  		.num_planes = 2,
>>  		.cpp = { 1, 2, 0 },
>> @@ -457,6 +478,7 @@ static const struct image_format_info formats[] = {
>>  		.is_yuv = true,
>>  	}, {
>>  		.drm_fmt = DRM_FORMAT_NV16,
>> +		.v4l2_fmt = V4L2_PIX_FMT_NV16,
>>  		.depth = 0,
>>  		.num_planes = 2,
>>  		.cpp = { 1, 2, 0 },
>> @@ -465,6 +487,7 @@ static const struct image_format_info formats[] = {
>>  		.is_yuv = true,
>>  	}, {
>>  		.drm_fmt = DRM_FORMAT_NV61,
>> +		.v4l2_fmt = V4L2_PIX_FMT_NV61,
>>  		.depth = 0,
>>  		.num_planes = 2,
>>  		.cpp = { 1, 2, 0 },
>> @@ -473,6 +496,7 @@ static const struct image_format_info formats[] = {
>>  		.is_yuv = true,
>>  	}, {
>>  		.drm_fmt = DRM_FORMAT_NV24,
>> +		.v4l2_fmt = V4L2_PIX_FMT_NV24,
>>  		.depth = 0,
>>  		.num_planes = 2,
>>  		.cpp = { 1, 2, 0 },
>> @@ -481,6 +505,7 @@ static const struct image_format_info formats[] = {
>>  		.is_yuv = true,
>>  	}, {
>>  		.drm_fmt = DRM_FORMAT_NV42,
>> +		.v4l2_fmt = V4L2_PIX_FMT_NV42,
>>  		.depth = 0,
>>  		.num_planes = 2,
>>  		.cpp = { 1, 2, 0 },
>> @@ -489,6 +514,7 @@ static const struct image_format_info formats[] = {
>>  		.is_yuv = true,
>>  	}, {
>>  		.drm_fmt = DRM_FORMAT_YUYV,
>> +		.v4l2_fmt = V4L2_PIX_FMT_YUYV,
>>  		.depth = 0,
>>  		.num_planes = 1,
>>  		.cpp = { 2, 0, 0 },
>> @@ -497,6 +523,7 @@ static const struct image_format_info formats[] = {
>>  		.is_yuv = true,
>>  	}, {
>>  		.drm_fmt = DRM_FORMAT_YVYU,
>> +		.v4l2_fmt = V4L2_PIX_FMT_YVYU,
>>  		.depth = 0,
>>  		.num_planes = 1,
>>  		.cpp = { 2, 0, 0 },
>> @@ -505,6 +532,7 @@ static const struct image_format_info formats[] = {
>>  		.is_yuv = true,
>>  	}, {
>>  		.drm_fmt = DRM_FORMAT_UYVY,
>> +		.v4l2_fmt = V4L2_PIX_FMT_UYVY,
>>  		.depth = 0,
>>  		.num_planes = 1,
>>  		.cpp = { 2, 0, 0 },
>> @@ -513,6 +541,7 @@ static const struct image_format_info formats[] = {
>>  		.is_yuv = true,
>>  	}, {
>>  		.drm_fmt = DRM_FORMAT_VYUY,
>> +		.v4l2_fmt = V4L2_PIX_FMT_VYUY,
>>  		.depth = 0,
>>  		.num_planes = 1,
>>  		.cpp = { 2, 0, 0 },
>> @@ -632,6 +661,44 @@ const struct image_format_info *image_format_drm_lookup(u32 drm)
>>  EXPORT_SYMBOL(image_format_drm_lookup);
>>  
>>  /**
>> + * __image_format_v4l2_lookup - query information for a given format
>> + * @v4l2: V4L2 fourcc pixel format (V4L2_PIX_FMT_*)
>> + *
>> + * The caller should only pass a supported pixel format to this function.
>> + *
>> + * Returns:
>> + * The instance of struct image_format_info that describes the pixel format, or
>> + * NULL if the format is unsupported.
>> + */
>> +const struct image_format_info *__image_format_v4l2_lookup(u32 v4l2)
>> +{
>> +	return __image_format_lookup(v4l2_fmt, v4l2);
>> +}
>> +EXPORT_SYMBOL(__image_format_v4l2_lookup);
>> +
>> +/**
>> + * image_format_v4l2_lookup - query information for a given format
>> + * @v4l2: V4L2 fourcc pixel format (V4L2_PIX_FMT_*)
>> + *
>> + * The caller should only pass a supported pixel format to this function.
>> + * Unsupported pixel formats will generate a warning in the kernel log.
>> + *
>> + * Returns:
>> + * The instance of struct image_format_info that describes the pixel format, or
>> + * NULL if the format is unsupported.
>> + */
>> +const struct image_format_info *image_format_v4l2_lookup(u32 v4l2)
>> +{
>> +	const struct image_format_info *format;
>> +
>> +	format = __image_format_v4l2_lookup(v4l2);
>> +
>> +	WARN_ON(!format);
>> +	return format;
>> +}
>> +EXPORT_SYMBOL(image_format_v4l2_lookup);
>> +
>> +/**
>>   * image_format_plane_cpp - determine the bytes per pixel value
>>   * @format: pointer to the image_format
>>   * @plane: plane index
>>
> 
> Anyway, I think this is a great improvement!
> 
> Regards,
> 
> 	Hans
>