linux-kernel - [PATCH 2/3] PM / Domains: Choose the deepest state to enter if no devices using it

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Message-Id: <20230913-multiple-state-scu-v1-2-9d91c6904ffa@nxp.com>
Date:   Wed, 13 Sep 2023 10:05:37 +0800
From:   "Peng Fan (OSS)" <peng.fan@....nxp.com>
To:     "Rafael J. Wysocki" <rafael@...nel.org>,
        Kevin Hilman <khilman@...nel.org>,
        Ulf Hansson <ulf.hansson@...aro.org>,
        Len Brown <len.brown@...el.com>, Pavel Machek <pavel@....cz>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Shawn Guo <shawnguo@...nel.org>,
        Sascha Hauer <s.hauer@...gutronix.de>,
        Pengutronix Kernel Team <kernel@...gutronix.de>,
        Fabio Estevam <festevam@...il.com>,
        NXP Linux Team <linux-imx@....com>
Cc:     linux-pm@...r.kernel.org, linux-kernel@...r.kernel.org,
        linux-arm-kernel@...ts.infradead.org,
        Dong Aisheng <aisheng.dong@....com>,
        Peng Fan <peng.fan@....com>
Subject: [PATCH 2/3] PM / Domains: Choose the deepest state to enter if no
 devices using it

From: Dong Aisheng <aisheng.dong@....com>

For a domain has no working devices anymore, let's choose the deepest state
to enter to save power. e.g. driver probe failure.

Signed-off-by: Dong Aisheng <aisheng.dong@....com>
Signed-off-by: Peng Fan <peng.fan@....com>
---
 drivers/base/power/domain.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/drivers/base/power/domain.c b/drivers/base/power/domain.c
index 22cfa3020b18..1887eb1b3130 100644
--- a/drivers/base/power/domain.c
+++ b/drivers/base/power/domain.c
@@ -730,6 +730,10 @@ static int genpd_power_off(struct generic_pm_domain *genpd, bool one_dev_on,
 	if (atomic_read(&genpd->sd_count) > 0)
 		return -EBUSY;
 
+	/* Choose the deepest state if no devices using this domain */
+	if (!genpd->device_count)
+		genpd->state_idx = genpd->state_count - 1;
+
 	ret = _genpd_power_off(genpd, true);
 	if (ret) {
 		genpd->states[genpd->state_idx].rejected++;

-- 
2.37.1