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

[Zhentao Guo]

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@xxxxxxxxxxx>
> >
> > 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@xxxxxxxxxxx>
> > ---
> >   .../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@xxxxxxxxxxx>
> > +
> > +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