linux-kernel - [PATCH 2/5] mmc: core: Further avoid re-storing power to the eMMC before a shutdown

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Message-ID: <20250320140040.162416-3-ulf.hansson@linaro.org>
Date: Thu, 20 Mar 2025 15:00:33 +0100
From: Ulf Hansson <ulf.hansson@...aro.org>
To: linux-mmc@...r.kernel.org,
	Ulf Hansson <ulf.hansson@...aro.org>
Cc: Adrian Hunter <adrian.hunter@...el.com>,
	Wolfram Sang <wsa+renesas@...g-engineering.com>,
	Yoshihiro Shimoda <yoshihiro.shimoda.uh@...esas.com>,
	linux-renesas-soc@...r.kernel.org,
	linux-kernel@...r.kernel.org
Subject: [PATCH 2/5] mmc: core: Further avoid re-storing power to the eMMC before a shutdown

To manage a graceful power-off of the eMMC card during platform shutdown,
the preferred option is to use the poweroff-notification command.

Due to an earlier suspend request the eMMC may already have been properly
powered-off, hence we are sometimes leaving the eMMC in its current state.
However, in one case when the host has MMC_CAP2_FULL_PWR_CYCLE_IN_SUSPEND
set we may unnecessarily restore the power to the eMMC, let's avoid this.

Signed-off-by: Ulf Hansson <ulf.hansson@...aro.org>
---
 drivers/mmc/core/mmc.c | 17 ++++++++++++++---
 1 file changed, 14 insertions(+), 3 deletions(-)

diff --git a/drivers/mmc/core/mmc.c b/drivers/mmc/core/mmc.c
index 3424bc9e20c5..400dd0449fec 100644
--- a/drivers/mmc/core/mmc.c
+++ b/drivers/mmc/core/mmc.c
@@ -2014,6 +2014,18 @@ static bool mmc_can_poweroff_notify(const struct mmc_card *card)
 		(card->ext_csd.power_off_notification == EXT_CSD_POWER_ON);
 }
 
+static bool mmc_may_poweroff_notify(const struct mmc_host *host,
+				    bool is_suspend)
+{
+	if (host->caps2 & MMC_CAP2_FULL_PWR_CYCLE)
+		return true;
+
+	if (host->caps2 & MMC_CAP2_FULL_PWR_CYCLE_IN_SUSPEND && is_suspend)
+		return true;
+
+	return !is_suspend;
+}
+
 static int mmc_poweroff_notify(struct mmc_card *card, unsigned int notify_type)
 {
 	unsigned int timeout = card->ext_csd.generic_cmd6_time;
@@ -2124,8 +2136,7 @@ static int _mmc_suspend(struct mmc_host *host, bool is_suspend)
 		goto out;
 
 	if (mmc_can_poweroff_notify(host->card) &&
-	    ((host->caps2 & MMC_CAP2_FULL_PWR_CYCLE) || !is_suspend ||
-	     (host->caps2 & MMC_CAP2_FULL_PWR_CYCLE_IN_SUSPEND)))
+	    mmc_may_poweroff_notify(host, is_suspend))
 		err = mmc_poweroff_notify(host->card, notify_type);
 	else if (mmc_can_sleep(host->card))
 		err = mmc_sleep(host);
@@ -2191,7 +2202,7 @@ static int mmc_shutdown(struct mmc_host *host)
 	 * before we can shutdown it properly.
 	 */
 	if (mmc_can_poweroff_notify(host->card) &&
-		!(host->caps2 & MMC_CAP2_FULL_PWR_CYCLE))
+	    !mmc_may_poweroff_notify(host, true))
 		err = _mmc_resume(host);
 
 	if (!err)
-- 
2.43.0