[RFC 0/7] media: Clean and make H264 stateless uAPI public

Ezequiel Garcia
2020-06-23T18:29:00Z

The recent patch posted by Jernej (which I'm including for context),
encouraged me to address all the known issues in the uAPI.

I hope we can finally make this uAPI interface
public; it would be nice to address the other codec
interfaces so we can move the codec drivers out of staging.

It should be noted that there is already GStreamer native
support for this interface, which will be part of 1.18,
once it's released [1], as well as support in Chromium [2].

The basic idea here is to sanitize the interface,
making sure the structs are aligned to 64-bit,
adding reserved fields for padding where suitable.

These reserved fields can then be used to support future extensions,
in case such need appears.

In addition to this, moving the slice invariant fields
to the per-frame control, makes the frame-mode driver
implementation much nicer and the interface; see patch 6/7 for details.

I'm not adding a MAINTAINERS entry, but I'd like to do so,
so we make sure any uAPI changes are sent to those involved.

Another potential change is the addition of a "Since:" tag to the
control specification, so we can document which kernel version
added the interface. This might prove useful if reserved
fields are then used to extend the interface.

Finally, I'm sneaking here a change from Philipp Zabel
which apparently fell thru the cracks.

[1] https://gitlab.freedesktop.org/gstreamer/gst-plugins-bad/-/tree/master/sys/v4l2codecs
[2] https://chromium.googlesource.com/chromium/src.git/+/refs/heads/master/media/gpu/v4l2/

Ezequiel Garcia (5):
fixup! media: uapi: h264: update reference lists
media: uapi: h264: increase size of fields
media: uapi: h264: pad v4l2_ctrl_h264_pps to 64-bit
media: uapi: h264: Clean slice invariants syntax elements
media: uapi: make H264 stateless codec interface public

Jernej Skrabec (1):
media: uapi: h264: update reference lists

Philipp Zabel (1):
media: uapi: h264: clarify pic_order_cnt_bit_size field

.../media/v4l/ext-ctrls-codec.rst | 135 ++++++++++++------
drivers/media/v4l2-core/v4l2-ctrls.c | 31 ++++
drivers/media/v4l2-core/v4l2-h264.c | 8 +-
.../staging/media/hantro/hantro_g1_h264_dec.c | 21 ++-
drivers/staging/media/hantro/hantro_h264.c | 3 +-
drivers/staging/media/hantro/hantro_hw.h | 5 +-
drivers/staging/media/rkvdec/rkvdec-h264.c | 6 +-
.../staging/media/sunxi/cedrus/cedrus_h264.c | 15 +-
include/media/v4l2-ctrls.h | 3 +-
include/media/v4l2-h264.h | 5 +-
.../linux/v4l2-h264-ctrls.h} | 73 ++++++----
11 files changed, 194 insertions(+), 111 deletions(-)
rename include/{media/h264-ctrls.h => uapi/linux/v4l2-h264-ctrls.h} (88%)

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2.26.0.rc2