linux-kernel - Re: [PATCH] clk: qcom: camcc-sc8280xp: Remove always-on GDSC hard-coding

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Message-ID: <6055cb14-de80-97bc-be23-7af8ffc89fcc@quicinc.com>
Date: Mon, 22 Jul 2024 14:27:33 +0530
From: "Satya Priya Kakitapalli (Temp)" <quic_skakitap@...cinc.com>
To: Bryan O'Donoghue <bryan.odonoghue@...aro.org>,
        Bjorn Andersson
	<andersson@...nel.org>,
        Michael Turquette <mturquette@...libre.com>,
        Stephen
 Boyd <sboyd@...nel.org>
CC: <dmitry.baryshkov@...aro.org>, <stable@...r.kernel.org>,
        <linux-arm-msm@...r.kernel.org>, <linux-clk@...r.kernel.org>,
        <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] clk: qcom: camcc-sc8280xp: Remove always-on GDSC
 hard-coding


On 7/20/2024 2:03 PM, Bryan O'Donoghue wrote:
> On 19/07/2024 08:25, Satya Priya Kakitapalli (Temp) wrote:
>>>
>>> What is the use-case to keep that clock always-on unless/util 
>>> someone wants camss ?
>>>
>>
>> The clock also has dependency on MMCX rail, this rail anyway will be 
>> OFF until there is a use-case. So the clock will also be OFF.
>
> arch/arm64/boot/dts/qcom/sc8280xp.dtsi
>
> camcc: clock-controller@...0000 {
>     power-domains = <&rpmhpd SC8280XP_MMCX>;
> };
>
>>
>>
>>> I've tested this patch on sc8280xp and it works just fine.
>>>
>>
>> Is the cam_cc_gdsc_clk clock ON after the boot up?
>
> I have no idea. Why does it matter ?
>

This clock expected to be kept always ON, as per design, or else the 
GDSC transition form ON to OFF (vice versa) wont work.

Want to know the clock status after bootup, to understand if the clock 
got turned off during the late init. May I know exactly what you have 
tested? Did you test the camera usecases as well?


> ---
> bod