linux-kernel - Re: [PATCH v3 0/2] media: cedrus: Add H264 decoding support

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Message-ID: <CAAFQd5AcqiwAb30ajLxmj6LZoabVygUsAB8A+drpityOAvY60A@mail.gmail.com>
Date:   Tue, 12 Feb 2019 21:50:18 +0900
From:   Tomasz Figa <tfiga@...omium.org>
To:     Maxime Ripard <maxime.ripard@...tlin.com>
Cc:     Hans Verkuil <hans.verkuil@...co.com>,
        Alexandre Courbot <acourbot@...omium.org>,
        Sakari Ailus <sakari.ailus@...ux.intel.com>,
        Laurent Pinchart <laurent.pinchart@...asonboard.com>,
        Pawel Osciak <posciak@...omium.org>,
        Paul Kocialkowski <paul.kocialkowski@...tlin.com>,
        Chen-Yu Tsai <wens@...e.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        "list@....net:IOMMU DRIVERS <iommu@...ts.linux-foundation.org>, Joerg
        Roedel <joro@...tes.org>," <linux-arm-kernel@...ts.infradead.org>,
        Linux Media Mailing List <linux-media@...r.kernel.org>,
        Nicolas Dufresne <nicolas.dufresne@...labora.com>,
        jenskuske@...il.com, Jernej Skrabec <jernej.skrabec@...il.com>,
        Jonas Karlman <jonas@...boo.se>,
        Ezequiel Garcia <ezequiel@...labora.com>,
        linux-sunxi@...glegroups.com,
        Thomas Petazzoni <thomas.petazzoni@...tlin.com>
Subject: Re: [PATCH v3 0/2] media: cedrus: Add H264 decoding support

Hi Maxime,

On Mon, Feb 11, 2019 at 11:39 PM Maxime Ripard
<maxime.ripard@...tlin.com> wrote:
>
> Hi,
>
> Here is a new version of the H264 decoding support in the cedrus
> driver.

Thanks for working on this. Please see my comments below.

>
> As you might already know, the cedrus driver relies on the Request
> API, and is a reverse engineered driver for the video decoding engine
> found on the Allwinner SoCs.
>
> This work has been possible thanks to the work done by the people
> behind libvdpau-sunxi found here:
> https://github.com/linux-sunxi/libvdpau-sunxi/
>
> I've tested the various ABI using this gdb script:
> http://code.bulix.org/jl4se4-505620?raw
>
> And this test script:
> http://code.bulix.org/8zle4s-505623?raw
>
> The application compiled is quite trivial:
> http://code.bulix.org/e34zp8-505624?raw
>
> The output is:
> arm:    builds/arm-test-v4l2-h264-structures
>         SHA1: 88cbf7485ba81831fc3b93772b215599b3b38318
> x86:    builds/x86-test-v4l2-h264-structures
>         SHA1: 88cbf7485ba81831fc3b93772b215599b3b38318
> x64:    builds/x64-test-v4l2-h264-structures
>         SHA1: 88cbf7485ba81831fc3b93772b215599b3b38318
> arm64:  builds/arm64-test-v4l2-h264-structures
>         SHA1: 88cbf7485ba81831fc3b93772b215599b3b38318
>
> Let me know if there's any flaw using that test setup, or if you have
> any comments on the patches.
>
> Maxime
>
> Changes from v2:
>   - Simplified _cedrus_write_ref_list as suggested by Jernej
>   - Set whether the frame is used as reference using nal_ref_idc
>   - Respect chroma_format_idc
>   - Fixes for the scaling list and prediction tables
>   - Wrote the documentation for the flags
>   - Added a bunch of defines to the driver bit fields
>   - Reworded the controls and data format descriptions as suggested
>     by Hans
>   - Reworked the controls' structure field size to avoid padding
>   - Removed the long term reference flag

This and...

>   - Reintroduced the neighbor info buffer
>   - Removed the ref_pic_list_p0/b0/b1 arrays that are redundant with the
>     one in the DPB

these are used in our Rockchip VDEC driver.

Could you elaborate on the reasons why they got removed?

Best regards,
Tomasz