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Message-Id: <20190530093312.27562-1-stanimir.varbanov@linaro.org>
Date: Thu, 30 May 2019 12:33:12 +0300
From: Stanimir Varbanov <stanimir.varbanov@...aro.org>
To: linux-media@...r.kernel.org
Cc: Mauro Carvalho Chehab <mchehab@...nel.org>,
Hans Verkuil <hverkuil@...all.nl>,
linux-kernel@...r.kernel.org, linux-arm-msm@...r.kernel.org,
Stanimir Varbanov <stanimir.varbanov@...aro.org>
Subject: [PATCH v3] 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@...aro.org>
---
Changes since v2:
Addressed review comments from Mauro.
.../media/uapi/v4l/pixfmt-v4l2-mplane.rst | 15 ++++++++++++++-
Documentation/media/uapi/v4l/pixfmt-v4l2.rst | 13 ++++++++++++-
2 files changed, 26 insertions(+), 2 deletions(-)
diff --git a/Documentation/media/uapi/v4l/pixfmt-v4l2-mplane.rst b/Documentation/media/uapi/v4l/pixfmt-v4l2-mplane.rst
index 5688c816e334..db43dda5aafb 100644
--- a/Documentation/media/uapi/v4l/pixfmt-v4l2-mplane.rst
+++ b/Documentation/media/uapi/v4l/pixfmt-v4l2-mplane.rst
@@ -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
diff --git a/Documentation/media/uapi/v4l/pixfmt-v4l2.rst b/Documentation/media/uapi/v4l/pixfmt-v4l2.rst
index 71eebfc6d853..da6da2ef139a 100644
--- a/Documentation/media/uapi/v4l/pixfmt-v4l2.rst
+++ b/Documentation/media/uapi/v4l/pixfmt-v4l2.rst
@@ -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`.
--
2.17.1
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