linux-kernel - Re: [PATCH v7 02/26] PM / Domains: Deal with multiple states but no governor in genpd

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Message-ID: <20180416173412.GE1209@codeaurora.org>
Date:   Mon, 16 Apr 2018 11:34:12 -0600
From:   Lina Iyer <ilina@...eaurora.org>
To:     Ulf Hansson <ulf.hansson@...aro.org>
Cc:     "Rafael J . Wysocki" <rjw@...ysocki.net>,
        Sudeep Holla <sudeep.holla@....com>,
        Lorenzo Pieralisi <Lorenzo.Pieralisi@....com>,
        Mark Rutland <mark.rutland@....com>, linux-pm@...r.kernel.org,
        Kevin Hilman <khilman@...nel.org>,
        Lina Iyer <lina.iyer@...aro.org>,
        Rob Herring <robh+dt@...nel.org>,
        Daniel Lezcano <daniel.lezcano@...aro.org>,
        Thomas Gleixner <tglx@...utronix.de>,
        Vincent Guittot <vincent.guittot@...aro.org>,
        Stephen Boyd <sboyd@...nel.org>,
        Juri Lelli <juri.lelli@....com>,
        Geert Uytterhoeven <geert+renesas@...der.be>,
        linux-arm-kernel@...ts.infradead.org,
        linux-arm-msm@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v7 02/26] PM / Domains: Deal with multiple states but no
 governor in genpd

On Thu, Apr 12 2018 at 05:14 -0600, Ulf Hansson wrote:
>A caller of pm_genpd_init() that provides some states for the genpd via the
>->states pointer in the struct generic_pm_domain, should also provide a
>governor. This because it's the job of the governor to pick a state that
>satisfies the constraints.
>
>Therefore, let's print a warning to inform the user about such bogus
>configuration and avoid to bail out, by instead picking the shallowest
>state before genpd invokes the ->power_off() callback.
>
>Cc: Lina Iyer <ilina@...eaurora.org>
>Signed-off-by: Ulf Hansson <ulf.hansson@...aro.org>

Reviewed-by: Lina Iyer <ilina@...eaurora.org>

>---
> drivers/base/power/domain.c | 6 ++++++
> 1 file changed, 6 insertions(+)
>
>diff --git a/drivers/base/power/domain.c b/drivers/base/power/domain.c
>index c2ef944..9aff79d 100644
>--- a/drivers/base/power/domain.c
>+++ b/drivers/base/power/domain.c
>@@ -466,6 +466,10 @@ static int genpd_power_off(struct generic_pm_domain *genpd, bool one_dev_on,
> 			return -EAGAIN;
> 	}
>
>+	/* Default to shallowest state. */
>+	if (!genpd->gov)
>+		genpd->state_idx = 0;
>+
> 	if (genpd->power_off) {
> 		int ret;
>
>@@ -1694,6 +1698,8 @@ int pm_genpd_init(struct generic_pm_domain *genpd,
> 		ret = genpd_set_default_power_state(genpd);
> 		if (ret)
> 			return ret;
>+	} else if (!gov) {
>+		pr_warn("%s : no governor for states\n", genpd->name);
> 	}
>
> 	mutex_lock(&gpd_list_lock);
>--
>2.7.4
>