linux-kernel - Re: [PATCH v3 2/9] dt-bindings: display: add verisilicon,dc

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Message-ID: <d4f07dbc7edb55d996d4d251acb9631f33e48f5e.camel@icenowy.me>
Date: Wed, 26 Nov 2025 18:24:22 +0800
From: Icenowy Zheng <uwu@...nowy.me>
To: Krzysztof Kozlowski <krzk@...nel.org>, Maarten Lankhorst
 <maarten.lankhorst@...ux.intel.com>, Maxime Ripard <mripard@...nel.org>, 
 Thomas Zimmermann <tzimmermann@...e.de>, David Airlie <airlied@...il.com>,
 Simona Vetter <simona@...ll.ch>, Rob Herring <robh@...nel.org>, Krzysztof
 Kozlowski <krzk+dt@...nel.org>, Conor Dooley <conor+dt@...nel.org>, Drew
 Fustini <fustini@...nel.org>, Guo Ren <guoren@...nel.org>, Fu Wei
 <wefu@...hat.com>, Philipp Zabel <p.zabel@...gutronix.de>, Heiko Stuebner
 <heiko@...ech.de>, Andrzej Hajda <andrzej.hajda@...el.com>, Neil Armstrong
 <neil.armstrong@...aro.org>,  Robert Foss <rfoss@...nel.org>, Laurent
 Pinchart <Laurent.pinchart@...asonboard.com>, Jonas Karlman
 <jonas@...boo.se>, Jernej Skrabec <jernej.skrabec@...il.com>, Michal
 Wilczynski <m.wilczynski@...sung.com>
Cc: Han Gao <rabenda.cn@...il.com>, Yao Zi <ziyao@...root.org>, 
	dri-devel@...ts.freedesktop.org, devicetree@...r.kernel.org, 
	linux-kernel@...r.kernel.org, linux-riscv@...ts.infradead.org
Subject: Re: [PATCH v3 2/9] dt-bindings: display: add verisilicon,dc

在 2025-11-26星期三的 11:22 +0100，Krzysztof Kozlowski写道：
> On 26/11/2025 10:50, Icenowy Zheng wrote:
> > > > +maintainers:
> > > > +  - Icenowy Zheng <uwu@...nowy.me>
> > > > +
> > > > +properties:
> > > > +  $nodename:
> > > > +    pattern: "^display@[0-9a-f]+$"
> > > > +
> > > > +  compatible:
> > > > +    items:
> > > > +      - enum:
> > > > +          - thead,th1520-dc8200
> > > > +      - const: verisilicon,dc
> > > 
> > > I do not see any explanation of exception for generic
> > > compatibles,
> > > maybe
> > > except "self-identification" remark. Rob already pointed this
> > > out, so
> > > be
> > > explicit in commit msg why you are using a generic compatible.
> > 
> > Well I only get the meaning of "a SoC specific compatible is
> > required"
> > in his review message.
> > 
> > I think my binding now requires both a SoC-specific compatible and
> > a
> > generic compatible, which should be okay to satisfy Rob's original
> > review.
> 
> You will get then the same questions for me - what justifies generic
> compatible. You should be on this explicit, because otherwise people
> misinterpret some commits and patches, and they think the generic
> compatible is allowed for them as well.
> 
> > 
> > > 
> > > > +
> > > > +  reg:
> > > > +    maxItems: 1
> > > > +
> > > > +  interrupts:
> > > > +    maxItems: 1
> > > > +
> > > > +  clocks:
> > > > +    minItems: 4
> > > 
> > > This is not flexible. Device either has or has not these clocks.
> > 
> > The existence of all these clocks are verified by diagrams in
> > manuals
> 
> So not flexible, then:
> 
> > of two different SoCs with DC8200 (T-Head TH1520 and StarFive
> > JH7110).
> > 
> > Maybe a explicit `maxItems: 5` is needed here, but as my DT passes
> > dtbs_check, I don't think it's necessary?
> 
> No, drop minItems only.

Well, okay, sounds reasonable.

> 
> > 
> > Or maybe I should drop the flexibility now and use a `minItems: 5`
> > here
> > (and leave DC8000 support as another story)? (The Eswin EIC7700
> > manual
> > does not have a diagram showing external connections of the DC,
> > like
> > the two SoCs I mentioned above).
> 
> You document here only the devices explicitly mentioned in the
> binding.
> You cannot add here constraints or clocks for some device which is
> not
> in the binding and I see only th1520 in the binding.
> 
> Best regards,
> Krzysztof