linux-kernel - [PATCH AUTOSEL 4.19 073/237] PM / Domains: Deal with multiple states but no governor in genpd

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Date:   Sat, 16 Nov 2019 10:38:28 -0500
From:   Sasha Levin <sashal@...nel.org>
To:     linux-kernel@...r.kernel.org, stable@...r.kernel.org
Cc:     Ulf Hansson <ulf.hansson@...aro.org>,
        Lina Iyer <ilina@...eaurora.org>,
        "Rafael J . Wysocki" <rafael.j.wysocki@...el.com>,
        Sasha Levin <sashal@...nel.org>, linux-pm@...r.kernel.org
Subject: [PATCH AUTOSEL 4.19 073/237] PM / Domains: Deal with multiple states but no governor in genpd

From: Ulf Hansson <ulf.hansson@...aro.org>

[ Upstream commit 2c9b7f8772033cc8bafbd4eefe2ca605bf3eb094 ]

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.

Signed-off-by: Ulf Hansson <ulf.hansson@...aro.org>
Reviewed-by: Lina Iyer <ilina@...eaurora.org>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@...el.com>
Signed-off-by: Sasha Levin <sashal@...nel.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 bf5be0bfaf773..52c292d0908a2 100644
--- a/drivers/base/power/domain.c
+++ b/drivers/base/power/domain.c
@@ -467,6 +467,10 @@ 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;
 
@@ -1686,6 +1690,8 @@ 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);
 	}
 
 	device_initialize(&genpd->dev);
-- 
2.20.1