linux-kernel - Re: [PATCH 2/2] clk: qcom: gdsc: Add pm

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Message-ID: <5lg7rsndxrcogrwywlciek4fdfejnpmvuibpwhh33whg2ebtlt@jli5g3qliota>
Date: Mon, 18 Nov 2024 15:39:08 +0200
From: Dmitry Baryshkov <dmitry.baryshkov@...aro.org>
To: Bryan O'Donoghue <bryan.odonoghue@...aro.org>
Cc: Bjorn Andersson <andersson@...nel.org>, 
	Michael Turquette <mturquette@...libre.com>, Stephen Boyd <sboyd@...nel.org>, linux-arm-msm@...r.kernel.org, 
	linux-clk@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 2/2] clk: qcom: gdsc: Add pm_runtime hooks

On Mon, Nov 18, 2024 at 01:19:49PM +0000, Bryan O'Donoghue wrote:
> On 18/11/2024 13:10, Dmitry Baryshkov wrote:
> > > Introduce pm_runtime_get() and pm_runtime_put_sync() on the
> > > gdsc_toggle_logic().
> > > 
> > > This allows for the switching of the GDSC on/off to propagate to the parent
> > > clock controller and consequently for any list of power-domains powering
> > > that controller to be switched on/off.
> > What is the end result of this patch? Does it bring up a single PM
> > domain or all of them? Or should it be a part of the driver's PM
> > callbacks? If the CC has multiple parent PM domains, shouldn't we also
> > use some of them as GDSC's parents?
> 
> It brings up every PM domain in the list
> 
> clock_cc {
>     power-domains = <somedomain0>, <another-domain>;
> };
> 
> No different to what the core code does for a single domain - except we can
> actually turn the PDs off with the pm_runtime_put().

I see. I missed the device link part of the dev_pm_domain_attach_list().

Just to check, have you checked that this provides no splats in
lockdep-enabled kernels? 
-- 
With best wishes
Dmitry