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

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Message-ID: <8dfc5456-861b-e01a-d2d2-1bb9adea1984@quicinc.com>
Date: Tue, 23 Jul 2024 17:07:07 +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 7/23/2024 2:59 PM, Bryan O'Donoghue wrote:
> On 22/07/2024 09:57, Satya Priya Kakitapalli (Temp) wrote:
>>> 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.
>
> Yes, parking to XO per this patch works for me. So I guess its already 
> on and is left in that state by the park.
>

Parking RCG to XO doesn't keep the branch clock always-on. It just keeps 
the parent RCG at 19.2MHz, branch can still be disabled by clearing 
bit(0). So during late init, the CCF will disable this clock(in 
clk_disable_unused API) if modelled. Hence this clock shouldn't be modelled.


>> 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?
>
> Of course.
>
> The camera works on x13s with this patch. That's what I mean by tested.
>
> ---
> bod