linux-kernel - Re: [PATCH 4/5] arm64: dts: qcom: r0q: enable hardware clocks

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Message-ID: <6E15B597-47E7-4233-9DBB-2DAC698F4532@gmail.com>
Date: Thu, 09 Oct 2025 16:20:38 -0300
From: Eric Gonçalves <ghatto404@...il.com>
To: Konrad Dybcio <konrad.dybcio@....qualcomm.com>,
 Bjorn Andersson <andersson@...nel.org>,
 Konrad Dybcio <konradybcio@...nel.org>, Rob Herring <robh@...nel.org>,
 Krzysztof Kozlowski <krzk+dt@...nel.org>, Conor Dooley <conor+dt@...nel.org>
CC: devicetree@...r.kernel.org, linux-arm-msm@...r.kernel.org,
 linux-kernel@...r.kernel.org
Subject: Re: [PATCH 4/5] arm64: dts: qcom: r0q: enable hardware clocks



On October 8, 2025 5:48:53 AM GMT-03:00, Konrad Dybcio <konrad.dybcio@....qualcomm.com> wrote:
>On 10/6/25 5:49 PM, Eric Gonçalves wrote:
>> 
>> 
>> On October 6, 2025 9:31:42 AM GMT-03:00, Konrad Dybcio <konrad.dybcio@....qualcomm.com> wrote:
>>> On 10/5/25 5:50 AM, Eric Gonçalves wrote:
>>>>
>>>>
>>>> On September 25, 2025 10:09:48 AM GMT-03:00, Konrad Dybcio <konrad.dybcio@....qualcomm.com> wrote:
>>>>> On 9/20/25 3:46 AM, Eric Gonçalves wrote:
>>>>>> Enable the real-time clocks found in R0Q board.
>>>>>>
>>>>>> Signed-off-by: Eric Gonçalves <ghatto404@...il.com>
>>>>>> ---
>>>>>>  arch/arm64/boot/dts/qcom/sm8450-samsung-r0q.dts | 15 +++++++++++++++
>>>>>>  1 file changed, 15 insertions(+)
>>>>>>
>>>>>> diff --git a/arch/arm64/boot/dts/qcom/sm8450-samsung-r0q.dts b/arch/arm64/boot/dts/qcom/sm8450-samsung-r0q.dts
>>>>>> index c1b0b21c0ec5..c088f1acf6ea 100644
>>>>>> --- a/arch/arm64/boot/dts/qcom/sm8450-samsung-r0q.dts
>>>>>> +++ b/arch/arm64/boot/dts/qcom/sm8450-samsung-r0q.dts
>>>>>> @@ -225,6 +225,21 @@ vol_up_n: vol-up-n-state {
>>>>>>  	};
>>>>>>  };
>>>>>>  
>>>>>> +&pmk8350_rtc {
>>>>>> +	nvmem-cells = <&rtc_offset>;
>>>>>> +	nvmem-cell-names = "offset";
>>>>>> +
>>>>>> +	status = "okay";
>>>>>> +};
>>>>>> +
>>>>>> +&pmk8350_sdam_2 {
>>>>>> +	status = "okay";
>>>>>> +
>>>>>> +	rtc_offset: rtc-offset@bc {
>>>>>
>>>>> Is this an offset you took from somewhere downstream?
>>>>>
>>>>> Generally you *really don't want to* poke at random SDAM cells,
>>>>> as they contain a lot of important settings (incl. battery/charging)
>>>> From another sm8450 device, I'm sure it's okay.
>>>
>>> That as an argument alone doesn't sound convincing to me, since vendors
>>> also sometimes repurpose unused-by-Qualcomm SDAM cells
>>>
>>> I actually found a data source internally and this cell you're trying
>>> to use is reserved for PBS (see drivers/soc/qcom/qcom-pbs.c), meaning
>>> you already fell into this trap..
>> Interesting, in this case then why does rtc still work? And
>> how can I find the real cell? It's not in downstream DT.
>
>Well if nothing accesses that cell between your last write and your first
>read, it will of course work, because SDAM is just a means of storage
>
>As for downstream/Android, it does not use SDAM at all
Alright, I'll drop this patch then, thanks
>
>Konrad