linux-kernel - Re: [PATCH v13 06/35] clk: tegra: Support runtime PM and power domain

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Message-ID: <7386079f-0dfe-9f55-6297-1f9ee67cd9d6@gmail.com>
Date:   Fri, 1 Oct 2021 22:50:04 +0300
From:   Dmitry Osipenko <digetx@...il.com>
To:     Ulf Hansson <ulf.hansson@...aro.org>
Cc:     Thierry Reding <thierry.reding@...il.com>,
        Jonathan Hunter <jonathanh@...dia.com>,
        Viresh Kumar <vireshk@...nel.org>,
        Stephen Boyd <sboyd@...nel.org>,
        Peter De Schrijver <pdeschrijver@...dia.com>,
        Mikko Perttunen <mperttunen@...dia.com>,
        Peter Chen <peter.chen@...nel.org>,
        Lee Jones <lee.jones@...aro.org>,
        Uwe Kleine-König <u.kleine-koenig@...gutronix.de>,
        Nishanth Menon <nm@...com>,
        Adrian Hunter <adrian.hunter@...el.com>,
        Michael Turquette <mturquette@...libre.com>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        linux-tegra <linux-tegra@...r.kernel.org>,
        Linux PM <linux-pm@...r.kernel.org>,
        Linux USB List <linux-usb@...r.kernel.org>,
        linux-staging@...ts.linux.dev, linux-pwm@...r.kernel.org,
        linux-mmc <linux-mmc@...r.kernel.org>,
        dri-devel <dri-devel@...ts.freedesktop.org>,
        DTML <devicetree@...r.kernel.org>,
        linux-clk <linux-clk@...r.kernel.org>,
        Mark Brown <broonie@...nel.org>,
        Vignesh Raghavendra <vigneshr@...com>,
        Richard Weinberger <richard@....at>,
        Miquel Raynal <miquel.raynal@...tlin.com>,
        Lucas Stach <dev@...xeye.de>, Stefan Agner <stefan@...er.ch>,
        Mauro Carvalho Chehab <mchehab@...nel.org>,
        David Heidelberg <david@...t.cz>
Subject: Re: [PATCH v13 06/35] clk: tegra: Support runtime PM and power domain

01.10.2021 15:32, Ulf Hansson пишет:
>> +static int tegra_clock_sync_pd_state(struct tegra_clk_device *clk_dev)
>> +{
>> +       unsigned long rate;
>> +       int ret = 0;
>> +
>> +       mutex_lock(&clk_dev->lock);
>> +
>> +       if (!pm_runtime_status_suspended(clk_dev->dev)) {
>> +               rate = clk_hw_get_rate(clk_dev->hw);
>> +               ret = tegra_clock_set_pd_state(clk_dev, rate);
> Don't we need to sync the performance state even when the device is
> runtime suspended?
> 
> Perhaps the clock, via a child-clock for example, can get
> prepared/enabled (hence its device gets runtime resumed) before there
> is a clock rate update for it. Then there is no performance state set
> for it, right? Or maybe that isn't a problem?
> 

Good catch! Older versions of this patch had a special handling for clk
enable/disable. I just forgot to update this function, it's now not a
problem to change performance state of a suspended device and it
actually needs to be done. I'll correct it, thanks!