Hi Boris,
Thanks for the review.
On Mon, 2019-06-17 at 15:23 +0200, Boris Brezillon wrote:
> On Thu, 13 Jun 2019 12:10:39 -0300
> Ezequiel Garcia <ezequiel@xxxxxxxxxxxxx> wrote:
>
> > From: Pawel Osciak <posciak@xxxxxxxxxxxx>
> >
> > Add the parsed VP8 frame pixel format and controls, to be used
> > with the new stateless decoder API for VP8 to provide parameters
> > for accelerator (aka stateless) codecs.
> >
> > Signed-off-by: Pawel Osciak <posciak@xxxxxxxxxxxx>
> > Signed-off-by: Ezequiel Garcia <ezequiel@xxxxxxxxxxxxx>
> > --
> > Changes from RFC:
> > * Make sure the uAPI has the same size on x86, x86_64, arm and arm64.
> > * Move entropy coder state fields to a struct.
> > * Move key_frame field to the flags.
> > * Remove unneeded first_part_offset field.
> > * Add documentation.
> > ---
> > Documentation/media/uapi/v4l/biblio.rst | 10 +
> > .../media/uapi/v4l/ext-ctrls-codec.rst | 311 ++++++++++++++++++
> > .../media/uapi/v4l/pixfmt-compressed.rst | 20 ++
> > drivers/media/v4l2-core/v4l2-ctrls.c | 8 +
> > drivers/media/v4l2-core/v4l2-ioctl.c | 1 +
> > include/media/v4l2-ctrls.h | 3 +
> > include/media/vp8-ctrls.h | 110 +++++++
> > 7 files changed, 463 insertions(+)
> > create mode 100644 include/media/vp8-ctrls.h
> >
> > diff --git a/Documentation/media/uapi/v4l/biblio.rst b/Documentation/media/uapi/v4l/biblio.rst
> > index 8f4eb8823d82..ad2ff258afa8 100644
> > --- a/Documentation/media/uapi/v4l/biblio.rst
> > +++ b/Documentation/media/uapi/v4l/biblio.rst
> > @@ -395,3 +395,13 @@ colimg
> > :title: Color Imaging: Fundamentals and Applications
> >
> > :author: Erik Reinhard et al.
> > +
> > +.. _vp8:
> > +
> > +VP8
> > +===
> > +
> > +
> > +:title: RFC 6386: "VP8 Data Format and Decoding Guide"
> > +
> > +:author: J. Bankoski et al.
> > diff --git a/Documentation/media/uapi/v4l/ext-ctrls-codec.rst b/Documentation/media/uapi/v4l/ext-ctrls-codec.rst
> > index d6ea2ffd65c5..7a1947f5be96 100644
> > --- a/Documentation/media/uapi/v4l/ext-ctrls-codec.rst
> > +++ b/Documentation/media/uapi/v4l/ext-ctrls-codec.rst
> > @@ -2234,6 +2234,317 @@ enum v4l2_mpeg_video_h264_hierarchical_coding_type -
> > Quantization parameter for a P frame for FWHT. Valid range: from 1
> > to 31.
> >
> > +.. _v4l2-mpeg-vp8:
> > +
> > +``V4L2_CID_MPEG_VIDEO_VP8_FRAME_HDR (struct)``
> > + Specifies the frame parameters for the associated VP8 parsed frame data.
> > + This includes the necessary parameters for
> > + configuring a stateless hardware decoding pipeline for VP8.
> > + The bitstream parameters are defined according to :ref:`vp8`.
> > +
> > + .. note::
> > +
> > + This compound control is not yet part of the public kernel API and
> > + it is expected to change.
> > +
> > +.. c:type:: v4l2_ctrl_vp8_frame_header
> > +
> > +.. cssclass:: longtable
> > +
> > +.. tabularcolumns:: |p{5.8cm}|p{4.8cm}|p{6.6cm}|
> > +
> > +.. flat-table:: struct v4l2_ctrl_vp8_frame_header
> > + :header-rows: 0
> > + :stub-columns: 0
> > + :widths: 1 1 2
> > +
> > + * - __u8
> > + - ``version``
> > + - Bitstream version.
> > + * - __u16
> > + - ``width``
> > + - The width of the frame
>
> Nit: sometimes you finish your description with a final dot sometimes
> not. It's probably better to make that consistent.
>
>
Yes, this is an overlook on my side. I'll fix this.
> [...]
>
> > diff --git a/include/media/vp8-ctrls.h b/include/media/vp8-ctrls.h
> > new file mode 100644
> > index 000000000000..3b0dcc125e25
> > --- /dev/null
> > +++ b/include/media/vp8-ctrls.h
> > @@ -0,0 +1,110 @@
> > +/* SPDX-License-Identifier: GPL-2.0 */
> > +/*
> > + * These are the VP8 state controls for use with stateless VP8
> > + * codec drivers.
> > + *
> > + * It turns out that these structs are not stable yet and will undergo
> > + * more changes. So keep them private until they are stable and ready to
> > + * become part of the official public API.
> > + */
> > +
> > +#ifndef _VP8_CTRLS_H_
> > +#define _VP8_CTRLS_H_
> > +
> > +#include <linux/v4l2-controls.h>
> > +
> > +#define V4L2_PIX_FMT_VP8_FRAME v4l2_fourcc('V', 'P', '8', 'F') /* VP8 parsed frames */
> > +
> > +#define V4L2_CID_MPEG_VIDEO_VP8_FRAME_HDR (V4L2_CID_MPEG_BASE + 2000)
> > +#define V4L2_CTRL_TYPE_VP8_FRAME_HDR 0x301
> > +
> > +#define V4L2_VP8_SEGMNT_HDR_FLAG_ENABLED 0x01
> > +#define V4L2_VP8_SEGMNT_HDR_FLAG_UPDATE_MAP 0x02
> > +#define V4L2_VP8_SEGMNT_HDR_FLAG_UPDATE_FEATURE_DATA 0x04
> > +
> > +struct v4l2_vp8_segment_header {
> > + __u8 segment_feature_mode;
> > + __s8 quant_update[4];
> > + __s8 lf_update[4];
> > + __u8 segment_probs[3];
> > + __u32 flags;
> > +};
> > +
> > +#define V4L2_VP8_LF_HDR_ADJ_ENABLE 0x01
> > +#define V4L2_VP8_LF_HDR_DELTA_UPDATE 0x02
> > +struct v4l2_vp8_loopfilter_header {
> > + __u16 type;
> > + __u8 level;
> > + __u8 sharpness_level;
> > + __s8 ref_frm_delta_magnitude[4];
> > + __s8 mb_mode_delta_magnitude[4];
> > + __u16 flags;
> > +};
> > +
> > +struct v4l2_vp8_quantization_header {
> > + __u8 y_ac_qi;
> > + __s8 y_dc_delta;
> > + __s8 y2_dc_delta;
> > + __s8 y2_ac_delta;
> > + __s8 uv_dc_delta;
> > + __s8 uv_ac_delta;
>
> Don't know what the policy in V4L, but it's usually a good thing to
> have structs used to exchange data with userspace aligned on 64-bits.
> Maybe you can add 2 padding bytes here. Note that the compiler might
> anyway add padding to align struct fields to their natural alignment in
> v4l2_ctrl_vp8_frame_header, so it's probably better to have these
> padding bytes explicitly defined and mandate that they be set to 0 so
> we can check them and complain when they're not 0.
>
AFAIK, there is no such requirement. There is however the requirement
of making sure the structs layout is the same on 32 and 64 architectures [1].
This is confirmed by these [2] tests which are based in Maxime's work.
[1] http://lkml.iu.edu/hypermail/linux/kernel/1806.1/05059.html
[2] https://gitlab.collabora.com/ezequiel/v4l2-ctrl-abi-check
> >
> > + __u16 dequant_factors[4][3][2];
> > +};
> > +
> > +struct v4l2_vp8_entropy_header {
> > + __u8 coeff_probs[4][8][3][11];
> > + __u8 y_mode_probs[4];
> > + __u8 uv_mode_probs[3];
> > + __u8 mv_probs[2][19];
>
> Same here
>
> > +};
> > +
> > +struct v4l2_vp8_entropy_coder_state {
> > + __u8 range;
> > + __u8 value;
> > + __u8 bit_count;
>
> and here.
>
> > +};
> > +
> > +#define V4L2_VP8_FRAME_HDR_FLAG_KEY_FRAME 0x01
> > +#define V4L2_VP8_FRAME_HDR_FLAG_EXPERIMENTAL 0x02
> > +#define V4L2_VP8_FRAME_HDR_FLAG_SHOW_FRAME 0x04
> > +#define V4L2_VP8_FRAME_HDR_FLAG_MB_NO_SKIP_COEFF 0x08
> > +
> > +#define VP8_FRAME_IS_KEY_FRAME(hdr) (!!(hdr->flags & V4L2_VP8_FRAME_HDR_FLAG_KEY_FRAME))
> > +
> > +struct v4l2_ctrl_vp8_frame_header {
> > + __u8 version;
> > +
>
> Maybe we should try to pack things so that the compiler does not
> implicitly add extra padding bytes. That implies trying to group u8
> fields by 2, 4 or 8 depending on what the next field natural alignment
> is.
>
Yes, I guess it makes sense to avoid implicit padding if possible.
> > + /* Populated also if not a key frame */
Note to self, this comment should be dropped and moved to the documentation.
> > + __u16 width;
> > + __u16 height;
> > + __u8 horizontal_scale;
> > + __u8 vertical_scale;
> > +
> > + struct v4l2_vp8_segment_header segment_header;
> > + struct v4l2_vp8_loopfilter_header lf_header;
> > + struct v4l2_vp8_quantization_header quant_header;
> > + struct v4l2_vp8_entropy_header entropy_header;
> > +
> > + __u16 sign_bias_golden;
> > + __u16 sign_bias_alternate;
> > +
> > + __u8 prob_skip_false;
> > + __u8 prob_intra;
> > + __u8 prob_last;
> > + __u8 prob_gf;
> > +
> > + __u32 first_part_size;
> > + __u32 macroblock_bit_offset;
> > + __u32 dct_part_sizes[8];
> > + __u8 num_dct_parts;
> > +
> > + struct v4l2_vp8_entropy_coder_state coder_state;
> > +
> > + __u64 last_frame_ts;
> > + __u64 golden_frame_ts;
> > + __u64 alt_frame_ts;
> > +
> > + __u64 flags;
> > +};
> > +
> > +#endif
Thanks,
Ezequiel
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