linux-kernel - Re: [PATCH] dt-bindings: rtc: zynqmp: Describe power-domains property

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Message-ID: <3f26624b-7c1d-43cb-a729-5fb50d184046@linaro.org>
Date: Mon, 19 Feb 2024 14:19:17 +0100
From: Krzysztof Kozlowski <krzysztof.kozlowski@...aro.org>
To: Michal Simek <michal.simek@....com>, linux-kernel@...r.kernel.org,
 monstr@...str.eu, michal.simek@...inx.com, git@...inx.com
Cc: Alexandre Belloni <alexandre.belloni@...tlin.com>,
 Conor Dooley <conor+dt@...nel.org>,
 Krzysztof Kozlowski <krzysztof.kozlowski+dt@...aro.org>,
 Rob Herring <robh@...nel.org>,
 "open list:OPEN FIRMWARE AND FLATTENED DEVICE TREE BINDINGS"
 <devicetree@...r.kernel.org>,
 "moderated list:ARM/ZYNQ ARCHITECTURE"
 <linux-arm-kernel@...ts.infradead.org>,
 "open list:REAL TIME CLOCK (RTC) SUBSYSTEM" <linux-rtc@...r.kernel.org>
Subject: Re: [PATCH] dt-bindings: rtc: zynqmp: Describe power-domains property

On 19/02/2024 14:11, Michal Simek wrote:
> 
> 
> On 2/17/24 09:26, Krzysztof Kozlowski wrote:
>> On 16/02/2024 10:42, Michal Simek wrote:
>>>
>>>
>>> On 2/16/24 10:19, Krzysztof Kozlowski wrote:
>>>> On 16/02/2024 09:51, Michal Simek wrote:
>>>>> RTC has its own power domain on Xilinx Versal SOC that's why describe it as
>>>>> optional property.
>>>>>
>>>>> Signed-off-by: Michal Simek <michal.simek@....com>
>>>>> ---
>>>>>
>>>>>    Documentation/devicetree/bindings/rtc/xlnx,zynqmp-rtc.yaml | 3 +++
>>>>>    1 file changed, 3 insertions(+)
>>>>>
>>>>
>>>> But Versal is not described in this binding, is it? I see only one
>>>> compatible.
>>>
>>> It is the same IP only as is on zynqmp with own power rail.
>>
>> Then you should have separate compatible, because they are not
>> identical. It would also allow you to narrow the domains to versal and
>> also require it (on versal).
> 
> I can double check with HW guys but I am quite sure IP itself is exactly the 
> same. What it is different is that there is own power domain to it (not shared 
> one as is in zynqmp case).

What does it mean shared one? If several devices share power domain,
then they all should have power-domains property.

> 
> Also Linux is non secure sw and if secure firmware won't allow to change setting 
> of it it can't be required. I am just saying that Linux doesn't need to be owner 
> of any power domain that's why it shouldn't be required property.


Best regards,
Krzysztof