linux-kernel - Re: [PATCH v3] cpuidle: psci: Do not suspend topology CPUs on PREEMPT

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Message-ID: <20230125111957.uzf2hli5md2pm43n@bogus>
Date:   Wed, 25 Jan 2023 11:19:57 +0000
From:   Sudeep Holla <sudeep.holla@....com>
To:     Ulf Hansson <ulf.hansson@...aro.org>
Cc:     Krzysztof Kozlowski <krzysztof.kozlowski@...aro.org>,
        Sudeep Holla <sudeep.holla@....com>,
        "Rafael J. Wysocki" <rafael@...nel.org>,
        Daniel Lezcano <daniel.lezcano@...aro.org>,
        Lorenzo Pieralisi <lpieralisi@...nel.org>,
        linux-pm@...r.kernel.org, linux-kernel@...r.kernel.org,
        linux-arm-kernel@...ts.infradead.org,
        Sebastian Andrzej Siewior <bigeasy@...utronix.de>,
        Adrien Thierry <athierry@...hat.com>,
        Brian Masney <bmasney@...hat.com>,
        linux-rt-users@...r.kernel.org
Subject: Re: [PATCH v3] cpuidle: psci: Do not suspend topology CPUs on
 PREEMPT_RT

On Wed, Jan 25, 2023 at 11:08:04AM +0100, Ulf Hansson wrote:
> On Wed, 25 Jan 2023 at 08:43, Krzysztof Kozlowski
> <krzysztof.kozlowski@...aro.org> wrote:
> >
> > On 24/01/2023 16:34, Sudeep Holla wrote:

[...]

> > > Any particular reason for even compiling this file in or allowing the
> > > ARM_PSCI_CPUIDLE when PREEMPT_RT=y ? If we can't enter idle states, we
> > > can as well compile this file out ?
> >
> > It's the power domain sued for other devices, so we need it. Otherwise
> > other devices will keep waiting for this missing power domain provider.
> 
> Yes.
> 
> And we are still able to use those idle states that are solely per
> CPU, which is probably nice to have. No?
> 

Makes sense, thanks for the explanation. Also the other discussions clears
probably questions I had.

-- 
Regards,
Sudeep