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media: media/doc: Allow sizeimage to be set by v4l clients 

This changes v4l2_pix_format and v4l2_plane_pix_format sizeimage
field description to allow v4l clients to set bigger image size
in case of variable length compressed data.

Presently s5p-mfc and mtk-vcodec codec drivers use that. Lets
make it obvious in the documentation.

Signed-off-by: Stanimir Varbanov <stanimir.varbanov@linaro.org>
Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>
Signed-off-by: Mauro Carvalho Chehab <mchehab+samsung@kernel.org>
This commit is contained in:
Stanimir Varbanov 2019-05-30 05:33:12 -04:00 committed by Mauro Carvalho Chehab
parent e96a8819a6
commit 84060c65a8
2 changed files with 26 additions and 2 deletions
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15
Documentation/media/uapi/v4l/pixfmt-v4l2-mplane.rst
View File

@ -31,7 +31,20 @@ describing all planes of that format.
* - __u32
- ``sizeimage``
- Maximum size in bytes required for image data in this plane.
- Maximum size in bytes required for image data in this plane,
set by the driver. When the image consists of variable length
compressed data this is the number of bytes required by the
codec to support the worst-case compression scenario.
The driver will set the value for uncompressed images.
Clients are allowed to set the sizeimage field for variable length
compressed data flagged with ``V4L2_FMT_FLAG_COMPRESSED`` at
:ref:`VIDIOC_ENUM_FMT`, but the driver may ignore it and set the
value itself, or it may modify the provided value based on
alignment requirements or minimum/maximum size requirements.
If the client wants to leave this to the driver, then it should
set sizeimage to 0.
* - __u32
- ``bytesperline``
- Distance in bytes between the leftmost pixels in two adjacent

13
Documentation/media/uapi/v4l/pixfmt-v4l2.rst
View File

@ -89,7 +89,18 @@ Single-planar format structure
- Size in bytes of the buffer to hold a complete image, set by the
driver. Usually this is ``bytesperline`` times ``height``. When
the image consists of variable length compressed data this is the
maximum number of bytes required to hold an image.
number of bytes required by the codec to support the worst-case
compression scenario.
The driver will set the value for uncompressed images.
Clients are allowed to set the sizeimage field for variable length
compressed data flagged with ``V4L2_FMT_FLAG_COMPRESSED`` at
:ref:`VIDIOC_ENUM_FMT`, but the driver may ignore it and set the
value itself, or it may modify the provided value based on
alignment requirements or minimum/maximum size requirements.
If the client wants to leave this to the driver, then it should
set sizeimage to 0.
* - __u32
- ``colorspace``
- Image colorspace, from enum :c:type:`v4l2_colorspace`.