linux-kernel - Re: [PATCH 1/3] dt-bindings: vdec: Add binding document of Amlogic decoder accelerator

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Message-ID: <40830266-692a-4731-8957-4462d4993746@amlogic.com>
Date: Tue, 28 Oct 2025 19:14:51 +0800
From: Zhentao Guo <zhentao.guo@...ogic.com>
To: Krzysztof Kozlowski <krzk@...nel.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,
 linux-amlogic@...ts.infradead.org
Subject: Re: [PATCH 1/3] dt-bindings: vdec: Add binding document of Amlogic
 decoder accelerator


在 2025/10/27 21:05, Krzysztof Kozlowski 写道:
> [You don't often get email from krzk@...nel.org. Learn why this is important at https://aka.ms/LearnAboutSenderIdentification ]
>
> [ EXTERNAL EMAIL ]
>
> On 27/10/2025 06:42, Zhentao Guo via B4 Relay wrote:
>> From: Zhentao Guo <zhentao.guo@...ogic.com>
>>
>> Add dt-binding of the Amlogic hardware decoder accelerator.
> Please use subject prefixes matching the subsystem. You can get them for
> example with `git log --oneline -- DIRECTORY_OR_FILE` on the directory
> your patch is touching. For bindings, the preferred subjects are
> explained here:
> https://www.kernel.org/doc/html/latest/devicetree/bindings/submitting-patches.html#i-for-patch-submitters
>
> A nit, subject: drop second/last, redundant "binding document for". The
> "dt-bindings" prefix is already stating that these are bindings.
> See also:
> https://elixir.bootlin.com/linux/v6.17-rc3/source/Documentation/devicetree/bindings/submitting-patches.rst#L18
Thank you for pointing this out and providing the guidance. We'll revise 
the subjects according to the specifications.
>> Signed-off-by: Zhentao Guo <zhentao.guo@...ogic.com>
>> ---
>>   .../bindings/media/amlogic,vcodec-dec.yaml         | 96 ++++++++++++++++++++++
>>   1 file changed, 96 insertions(+)
>>
>> diff --git a/Documentation/devicetree/bindings/media/amlogic,vcodec-dec.yaml b/Documentation/devicetree/bindings/media/amlogic,vcodec-dec.yaml
>> new file mode 100644
>> index 000000000000..6cea8af72639
>> --- /dev/null
>> +++ b/Documentation/devicetree/bindings/media/amlogic,vcodec-dec.yaml
> Filename matching compatible.
Yes, we will correct this.
>> @@ -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
>> +---
>> +$id: http://devicetree.org/schemas/media/amlogic,vcodec-dec.yaml#
>> +$schema: http://devicetree.org/meta-schemas/core.yaml#
>> +
>> +title: Amlogic Video Decode Accelerator
>> +
>> +maintainers:
>> +  - Zhentao Guo <zhentao.guo@...ogic.com>
>> +
>> +description: |
>
> Do not need '|' unless you need to preserve formatting.
OK, I'll get rid of this.
>> +  The Video Decoder Accelerator present on Amlogic SOCs.
>> +  It supports stateless h264 decoding.
>> +
>> +properties:
>> +  compatible:
>> +    const: amlogic,s4-vcodec-dec
>> +
>> +  reg:
>> +    maxItems: 2
>> +
>> +  reg-names:
>> +    items:
>> +      - const: dosbus
>> +      - const: dmcbus
> Is "bus" really name of this in datasheet?
No, it is not from the datasheet, in fact it was inherited from the
older SOCs. Do you have any suggestions about this?
>> +
>> +  interrupts:
>> +    maxItems: 3
>> +
>> +  interrupt-names:
>> +    items:
>> +      - const: mailbox_0
>> +      - const: mailbox_1
>> +      - const: mailbox_2
> Useless names, so just drop interrupt-names property.
Yes, we don't need the interrupt names. I'll drop them.
>
>> +
>> +  clocks:
>> +    maxItems: 3
>> +
>> +  clock-names:
>> +    items:
>> +      - const: vdec
>> +      - const: clk_vdec_mux
>> +      - const: clk_hevcf_mux
>> +
>> +  power-domains:
>> +    maxItems: 2
>> +
>> +  power-domain-names:
>> +    items:
>> +      - const: pwrc-vdec
> Drop pwrc
>
>> +      - const: pwrc-hevc
> Drop pwrc
Ok, I'll drop the two pwrc(s) above.
>
> Missing iommus. I really doubt hardware works without IOMMU.

IOMMU is not supported by Amlogic SOCs, the decoder hardware needs to 
use contiguous memory.

>
>
> Best regards,
> Krzysztof