Re: [PATCH RFC v4 1/4] media: dt-bindings: Add Amlogic V4L2 video decoder

[Zhentao Guo <zhentao.guo@amlogic.com>]

在 2026/2/13 15:35, Krzysztof Kozlowski 写道:
> [ EXTERNAL EMAIL ]
>
> On 13/02/2026 06:12, Zhentao Guo via B4 Relay wrote:
>> From: Zhentao Guo <zhentao.guo@amlogic.com>
>>
>> Describe the initial support for the V4L2 stateless video decoder
>> driver used with the Amlogic S4 (S805X2) platform.
>>
>> Signed-off-by: Zhentao Guo <zhentao.guo@amlogic.com>
>> ---
>>   .../bindings/media/amlogic,s4-vcodec-dec.yaml      | 96 ++++++++++++++++++++++
>>   1 file changed, 96 insertions(+)
>>
>> diff --git a/Documentation/devicetree/bindings/media/amlogic,s4-vcodec-dec.yaml b/Documentation/devicetree/bindings/media/amlogic,s4-vcodec-dec.yaml
>> new file mode 100644
>> index 000000000000..88780514d06c
>> --- /dev/null
>> +++ b/Documentation/devicetree/bindings/media/amlogic,s4-vcodec-dec.yaml
>> @@ -0,0 +1,96 @@
>> +# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
>> +# Copyright (C) 2025 Amlogic, Inc. All rights reserved
>> +%YAML 1.2
>> +---
>> +$id: http://devicetree.org/schemas/media/amlogic,s4-vcodec-dec.yaml#
>> +$schema: http://devicetree.org/meta-schemas/core.yaml#
>> +
>> +title: Amlogic Video Decode Accelerator
>> +
>> +maintainers:
>> +  - Zhentao Guo <zhentao.guo@amlogic.com>
>> +
>> +description:
>> +  The Video Decoder Accelerator present on Amlogic SOCs.
>> +  It supports stateless h264 decoding.
>> +
>> +properties:
>> +  compatible:
>> +    const: amlogic,s4-vcodec-dec
> Why do you repeat "dec" twice? codec means decoder, so what is the last
> "dec" about?
In fact, codec means encoder+decoder, and dec is short for decoder.
>> +
>> +  reg:
>> +    maxItems: 2
>> +
>> +  reg-names:
>> +    items:
>> +      - const: dos
>> +      - const: dmc
>> +
>> +  interrupts:
>> +    maxItems: 3
>> +
>> +  clocks:
>> +    maxItems: 3
>> +
>> +  clock-names:
>> +    items:
>> +      - const: vdec
>> +      - const: clk_vdec_mux
>> +      - const: clk_hevcf_mux
> Name them based on their role/name in this device. Why this device would
> care that it receives a mux? Not a div? or not a gate?
Ok, previously we overlooked this. We will improve it in the next version.
>> +
>> +  power-domains:
>> +    maxItems: 2
>> +
>> +  power-domain-names:
>> +    items:
>> +      - const: vdec
>> +      - const: hevc
>> +
>> +  resets:
>> +    maxItems: 1
>> +
>> +  amlogic,canvas:
>> +    description: should point to a canvas provider node
> Why? What for?
>
> What is canvas provider?

The canvas provider is: drivers/soc/amlogic/meson-canvas.c

In short, canvas is a hardware IP inside the Amlogic SoC. The decoder IP 
needs to access DDR through canvas IP, so we need to reference the 
canvas driver.

>> +    $ref: /schemas/types.yaml#/definitions/phandle
>> +
>> +required:
>> +  - compatible
>> +  - reg
>> +  - reg-names
>> +  - interrupts
>> +  - clocks
>> +  - clock-names
>> +  - power-domains
>> +  - power-domain-names
>> +
> Best regards,
> Krzysztof

BRs

Zhentao


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