linux-kernel - Re: [PATCH 1/2] dt-bindings: pwm: sophgo: add pwm controller for SG2044

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Message-ID: <3y4nm5ievsfyomyzm35b3moj2buunwmisjowmvovhbglcjwnhi@gaj7wz4sm7tj>
Date: Tue, 8 Apr 2025 10:33:32 +0800
From: Inochi Amaoto <inochiama@...il.com>
To: Rob Herring <robh@...nel.org>, 
	Uwe Kleine-König <ukleinek@...nel.org>
Cc: Longbin Li <looong.bin@...il.com>, 
	Krzysztof Kozlowski <krzk+dt@...nel.org>, Conor Dooley <conor+dt@...nel.org>, 
	Chen Wang <unicorn_wang@...look.com>, Inochi Amaoto <inochiama@...il.com>, 
	Paul Walmsley <paul.walmsley@...ive.com>, Palmer Dabbelt <palmer@...belt.com>, 
	Albert Ou <aou@...s.berkeley.edu>, Alexandre Ghiti <alex@...ti.fr>, ghost <2990955050@...com>, 
	linux-pwm@...r.kernel.org, devicetree@...r.kernel.org, sophgo@...ts.linux.dev, 
	linux-kernel@...r.kernel.org, linux-riscv@...ts.infradead.org
Subject: Re: [PATCH 1/2] dt-bindings: pwm: sophgo: add pwm controller for
 SG2044

On Mon, Apr 07, 2025 at 09:11:19AM -0500, Rob Herring wrote:
> On Mon, Apr 07, 2025 at 02:31:24PM +0200, Uwe Kleine-König wrote:
> > Hello,
> > 
> > On Mon, Apr 07, 2025 at 03:20:38PM +0800, Longbin Li wrote:
> > > diff --git a/Documentation/devicetree/bindings/pwm/sophgo,sg2042-pwm.yaml b/Documentation/devicetree/bindings/pwm/sophgo,sg2042-pwm.yaml
> > > index bbb6326d47d7..e0e91aa237ec 100644
> > > --- a/Documentation/devicetree/bindings/pwm/sophgo,sg2042-pwm.yaml
> > > +++ b/Documentation/devicetree/bindings/pwm/sophgo,sg2042-pwm.yaml
> > > @@ -17,7 +17,9 @@ allOf:
> > > 
> > >  properties:
> > >    compatible:
> > > -    const: sophgo,sg2042-pwm
> > > +    enum:
> > > +      - sophgo,sg2042-pwm
> > > +      - sophgo,sg2044-pwm
> > 
> > Given that the sg2044 has more registers (to e.g. implement different
> > polarity), but the sg2042 registers are identical, I wonder if the 2044
> > device should use:
> > 
> > 	compatible = "sophgo,sg2044-pwm", "sophgo,sg2042-pwm";
> > 
> > Note, I'm unsure here, only providing input to people who are more
> > knowledgeable in DT that I am.
> 
> Depends if s/w only understanding "sophgo,sg2042-pwm" will work on the 
> 2044. IOW, will a kernel without the driver change here work?
> 

No luck, the logic for SG2042 is broken on SG2044. In fact, it seems
to be more familiar to the pwm ip on CV1800 than it on SG2042.

Regards,
Inochi