linux-kernel - Re: [PATCH v2] PM: domains: Prevent power off for parent unless child is in deepest state

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Message-ID: <dd7d0ebd-7bd8-9f2e-e212-5b597ec729d5@gmail.com>
Date:   Wed, 16 Feb 2022 00:49:50 +0300
From:   Dmitry Osipenko <digetx@...il.com>
To:     Ulf Hansson <ulf.hansson@...aro.org>,
        "Rafael J . Wysocki" <rafael@...nel.org>, linux-pm@...r.kernel.org
Cc:     Kevin Hilman <khilman@...nel.org>,
        Alexandre Torgue <alexandre.torgue@...s.st.com>,
        Geert Uytterhoeven <geert+renesas@...der.be>,
        Rajendra Nayak <rnayak@...eaurora.org>,
        Dong Aisheng <aisheng.dong@....com>,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2] PM: domains: Prevent power off for parent unless child
 is in deepest state

04.02.2022 13:16, Ulf Hansson пишет:
> A PM domain managed by genpd may support multiple idlestates. During
> genpd_power_off() a genpd governor may be asked to select one of the
> idlestates based upon the dev PM QoS constraints, for example.
> 
> However, there is a problem with the behaviour around this in genpd. More
> precisely, a parent-domain is allowed to be powered off, no matter of what
> idlestate that has been selected for the child-domain.
> 
> So far, we have not received any reports about errors from the current
> behaviour. However, there is an STMicro platform that is being worked on,
> which can't cope with this.

Could you please provide some technical info about why STMicro platform
can't cope with that?