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From:   Ulf Hansson <ulf.hansson@linaro.org>
Date:   Tue, 25 Oct 2022 14:58:33 +0200
Message-ID: <CAPDyKFoQCvga_gjsvHfi3W=zETX2J9c8SnXH5xD6QDaVQ_C8-Q@mail.gmail.com>
Subject: Re: [PATCH] PM: domains: Fix handling of unavailable/disabled idle states
To:     "Rafael J. Wysocki" <rafael@kernel.org>,
        Sudeep Holla <sudeep.holla@arm.com>,
        Amit Pundir <amit.pundir@linaro.org>
Cc:     linux-pm@vger.kernel.org, linux-kernel@vger.kernel.org,
        Bjorn Andersson <andersson@kernel.org>,
        Andy Gross <agross@kernel.org>,
        Dmitry Baryshkov <dmitry.baryshkov@linaro.org>
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On Tue, 25 Oct 2022 at 14:34, Sudeep Holla <sudeep.holla@arm.com> wrote:
>
> Platforms can provide the information about the availability of each
> idle states via status flag. Platforms may have to disable one or more
> idle states for various reasons like broken firmware or other unmet
> dependencies.
>
> Fix handling of such unavailable/disabled idle states by ignoring them
> while parsing the states.
>
> Cc: "Rafael J. Wysocki" <rafael@kernel.org>
> Cc: Ulf Hansson <ulf.hansson@linaro.org>
> Fixes: a3381e3a65cb ("PM / domains: Fix up domain-idle-states OF parsing")
> Signed-off-by: Sudeep Holla <sudeep.holla@arm.com>

I think this should be tagged for stable kernels too. Rafael, can you
pick this up as a fix for v6.1rc[n]?

Reviewed-by: Ulf Hansson <ulf.hansson@linaro.org>

Kind regards
Uffe

> ---
>  drivers/base/power/domain.c | 4 ++++
>  1 file changed, 4 insertions(+)
>
> Hi Ulf,
>
> As you already know, this change alone doesn't fix the issue reported here[1].
> It also needs the fixes you have posted [2].
>
> Regards,
> Sudeep
>
> [1] https://lore.kernel.org/all/20221018145348.4051809-1-amit.pundir@linaro.org
> [2] https://lore.kernel.org/all/20221021151013.148457-1-ulf.hansson@linaro.org

Well, I think it's better if we replace [1] with a patch that only
disables the cluster idle state. In that case, it would be sufficient
with $subject patch. In that case, we can just manage [2] separately.

Amit, can you submit a new version and test it together with $subject patch?

Kind regards
Uffe

>
> diff --git a/drivers/base/power/domain.c b/drivers/base/power/domain.c
> index ead135c7044c..6471b559230e 100644
> --- a/drivers/base/power/domain.c
> +++ b/drivers/base/power/domain.c
> @@ -2952,6 +2952,10 @@ static int genpd_iterate_idle_states(struct device_node *dn,
>                 np = it.node;
>                 if (!of_match_node(idle_state_match, np))
>                         continue;
> +
> +               if (!of_device_is_available(np))
> +                       continue;
> +
>                 if (states) {
>                         ret = genpd_parse_state(&states[i], np);
>                         if (ret) {
> --
> 2.38.1
>