linux-kernel - Re: [RFC PATCH v2 01/19] dt-bindings: clock: Add VO subsystem clocks and update address requirements

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Message-ID: <wjet4yvtcobjaf7c4u7to6rm3ppkvmgyitp6evoqjpndtno6qg@h5xxyukph6y6>
Date: Tue, 24 Dec 2024 09:53:41 +0100
From: Krzysztof Kozlowski <krzk@...nel.org>
To: Stephen Boyd <sboyd@...nel.org>
Cc: Michal Wilczynski <m.wilczynski@...sung.com>, airlied@...il.com, 
	aou@...s.berkeley.edu, conor+dt@...nel.org, drew@...7.com, frank.binns@...tec.com, 
	guoren@...nel.org, jassisinghbrar@...il.com, jszhang@...nel.org, krzk+dt@...nel.org, 
	m.szyprowski@...sung.com, maarten.lankhorst@...ux.intel.com, matt.coster@...tec.com, 
	mripard@...nel.org, mturquette@...libre.com, p.zabel@...gutronix.de, 
	palmer@...belt.com, paul.walmsley@...ive.com, robh@...nel.org, simona@...ll.ch, 
	tzimmermann@...e.de, ulf.hansson@...aro.org, wefu@...hat.com, 
	linux-clk@...r.kernel.org, devicetree@...r.kernel.org, linux-kernel@...r.kernel.org, 
	linux-riscv@...ts.infradead.org, dri-devel@...ts.freedesktop.org, linux-pm@...r.kernel.org
Subject: Re: [RFC PATCH v2 01/19] dt-bindings: clock: Add VO subsystem clocks
 and update address requirements

On Mon, Dec 23, 2024 at 12:50:59PM -0800, Stephen Boyd wrote:
> Quoting Michal Wilczynski (2024-12-23 04:55:35)
> > The T-Head TH1520 SoC’s AP clock controller now needs two address ranges
> > to manage both the Application Processor (AP) and Video Output (VO)
> > subsystem clocks. Update the device tree bindings to require two `reg`
> > entries, one for the AP clocks and one for the VO clocks.
> > 
> > Additionally, introduce new VO subsystem clock constants in the header
> > file. These constants will be used by the driver to control VO-related
> > components such as display and graphics units.
> > 
> > Signed-off-by: Michal Wilczynski <m.wilczynski@...sung.com>
> > ---
> [...]
> > diff --git a/Documentation/devicetree/bindings/clock/thead,th1520-clk-ap.yaml b/Documentation/devicetree/bindings/clock/thead,th1520-clk-ap.yaml
> > index 0129bd0ba4b3..f0df97a450ef 100644
> > --- a/Documentation/devicetree/bindings/clock/thead,th1520-clk-ap.yaml
> > +++ b/Documentation/devicetree/bindings/clock/thead,th1520-clk-ap.yaml
> > @@ -47,7 +54,9 @@ examples:
> >      #include <dt-bindings/clock/thead,th1520-clk-ap.h>
> >      clock-controller@...10000 {
> >          compatible = "thead,th1520-clk-ap";
> > -        reg = <0xef010000 0x1000>;
> > +        reg = <0xef010000 0x1000>,
> > +              <0xff010000 0x1000>;
> 
> I don't get it. Why not have two nodes and two devices? They have
> different register regions so likely they're different devices on the
> internal SoC bus. They may have the same input clks, but otherwise I
> don't see how they're the same node.

That's a good point. Aren't here simply two different clock controllers?

Best regards,
Krzysztof