linux-kernel - Re: [PATCH 03/15] clk: qcom: gcc-sm6375: Unregister critical clocks

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Message-ID: <33a26241-026a-9466-5dd6-e3202b29f57c@linaro.org>
Date:   Tue, 18 Jul 2023 15:26:51 +0200
From:   Konrad Dybcio <konrad.dybcio@...aro.org>
To:     Johan Hovold <johan@...nel.org>
Cc:     Bjorn Andersson <andersson@...nel.org>,
        Andy Gross <agross@...nel.org>,
        Michael Turquette <mturquette@...libre.com>,
        Stephen Boyd <sboyd@...nel.org>,
        Rob Herring <robh+dt@...nel.org>,
        Krzysztof Kozlowski <krzysztof.kozlowski+dt@...aro.org>,
        Conor Dooley <conor+dt@...nel.org>,
        Marijn Suijten <marijn.suijten@...ainline.org>,
        linux-arm-msm@...r.kernel.org, linux-clk@...r.kernel.org,
        linux-kernel@...r.kernel.org, devicetree@...r.kernel.org
Subject: Re: [PATCH 03/15] clk: qcom: gcc-sm6375: Unregister critical clocks

On 18.07.2023 15:20, Johan Hovold wrote:
> On Mon, Jul 17, 2023 at 05:19:10PM +0200, Konrad Dybcio wrote:
>> Some clocks need to be always-on, but we don't really do anything
>> with them, other than calling enable() once and telling Linux they're
>> enabled.
>>
>> Unregister them to save a couple of bytes and, perhaps more
>> importantly, allow for runtime suspend of the clock controller device,
>> as CLK_IS_CRITICAL prevents the latter.
> 
> But this doesn't sound right. How can you disable a controller which
> still has clocks enabled?
> 
> Shouldn't instead these clocks be modelled properly so that they are
> only enabled when actually needed?
Hm.. We do have clk_branch2_aon_ops, but something still needs to
toggle these clocks.

I *think* we could leave a permanent vote in probe() without breaking
runtime pm! I'll give it a spin bit later..

Konrad