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

From: Ferass El Hafidi <funderscore@postmarketos.org>
To: linux-amlogic@lists.infradead.org, zhentao.guo@amlogic.com,
	Mauro Carvalho Chehab <mchehab@kernel.org>,
	Rob Herring <robh@kernel.org>,
	Krzysztof Kozlowski <krzk+dt@kernel.org>,
	Conor Dooley <conor+dt@kernel.org>,
	Neil Armstrong <neil.armstrong@linaro.org>,
	Kevin Hilman <khilman@baylibre.com>,
	Jerome Brunet <jbrunet@baylibre.com>,
	Martin Blumenstingl <martin.blumenstingl@googlemail.com>
Cc: linux-media@vger.kernel.org, devicetree@vger.kernel.org,
	linux-kernel@vger.kernel.org,
	linux-arm-kernel@lists.infradead.org,
	linux-amlogic@lists.infradead.org,
	Zhentao Guo <zhentao.guo@amlogic.com>
Subject: Re: [PATCH RFC v2 0/3] Add Amlogic stateless H.264 video decoder for S4
Date: Tue, 25 Nov 2025 10:55:30 +0000	[thread overview]
Message-ID: <t6a43h.17cuodq0mx1pi@postmarketos.org> (raw)
In-Reply-To: <20251124-b4-s4-vdec-upstream-v2-0-bdbbce3f11a6@amlogic.com>

Hello, quick drive-by comments:

On Mon, 24 Nov 2025 03:32, Zhentao Guo via B4 Relay <devnull+zhentao.guo.amlogic.com@kernel.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?

>- 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

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