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: <c17c75c0-ef13-48df-9095-67fbf31bb817@samsung.com>
Date: Tue, 24 Dec 2024 10:23:24 +0100
From: Michal Wilczynski <m.wilczynski@...sung.com>
To: Krzysztof Kozlowski <krzk@...nel.org>, Stephen Boyd <sboyd@...nel.org>
Cc: 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 12/24/24 09:53, Krzysztof Kozlowski wrote:
> 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?

Yeah there are two clock controllers, based on the review comments I was
trying to re-use the driver, but the driver can also be re-used to serve
multiple nodes and multiple compatible and .data properties, if that's
fine with you that's how it will look like in v3.

Thanks,
Michał
> 
> Best regards,
> Krzysztof
> 
>