linux-kernel - Re: [PATCH RFC v2 0/3] Add Amlogic stateless H.264 video decoder for S4

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Message-ID: <9051a983-97e5-46d9-b428-335fa9769441@amlogic.com>
Date: Tue, 25 Nov 2025 19:15:05 +0800
From: Zhentao Guo <zhentao.guo@...ogic.com>
To: Ferass El Hafidi <funderscore@...tmarketos.org>,
 linux-amlogic@...ts.infradead.org, Mauro Carvalho Chehab
 <mchehab@...nel.org>, Rob Herring <robh@...nel.org>,
 Krzysztof Kozlowski <krzk+dt@...nel.org>, Conor Dooley
 <conor+dt@...nel.org>, Neil Armstrong <neil.armstrong@...aro.org>,
 Kevin Hilman <khilman@...libre.com>, Jerome Brunet <jbrunet@...libre.com>,
 Martin Blumenstingl <martin.blumenstingl@...glemail.com>
Cc: linux-media@...r.kernel.org, devicetree@...r.kernel.org,
 linux-kernel@...r.kernel.org, linux-arm-kernel@...ts.infradead.org
Subject: Re: [PATCH RFC v2 0/3] Add Amlogic stateless H.264 video decoder for
 S4


在 2025/11/25 18:55, Ferass El Hafidi 写道:
> [ EXTERNAL EMAIL ]
>
> Hello, quick drive-by comments:
>
> On Mon, 24 Nov 2025 03:32, Zhentao Guo via B4 Relay 
> <devnull+zhentao.guo.amlogic.com@...nel.org> wrote:
>> Introduce initial driver support for Amlogic's new video acceleration
>> hardware architecture, designed for video stream decoding.
>>
>> Compared to the current Amlogic video decoder hardware architecture,
>> this new implementation eliminates the Esparser hardware component,
>> enabling direct vb2 buffer input. The driver is designed to support
>> the V4L2 M2M stateless decoder API. The initial phase includes support
>> for H.264 decoding on Amlogic S805X2 platform.
>>
>> The driver is capable of:
>> - Supporting stateless H.264 decoding up to a resolution 1920x1088(on 
>> the S805X2 platform).
>
> nit: 1920x1080?
The hardware requires the height to be aligned to 16 pixels, so 1080 is 
not a multiple of 16, but 1088 is. Therefore, the hardware actually 
supports 1920x1088 for decoding, which covers 1920x1080 by padding the 
height to 1088.
>
>> - Supporting I/P/B frame handling.
>> - Supporting vb2 mmap and dma-buf modes.
>> - Supporting frame-based decode mode. (Note that some H.264 
>> bitstreams require
>>  DPB reordering to generate reference lists, the stateless decoder 
>> driver
>>  cannot access reordered reference lists in this mode, requiring the 
>> driver
>>  to perform reference list reordering itself)
>> - Supporting NV12/NV21 output.
>> - Supporting Annex B start codes.
>
> Best regards,
> Ferass

BRs

Zhentao