linux-kernel - [PATCH v2 2/5] mmc: core: Further avoid re-storing power to the eMMC before a shutdown

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Message-ID: <20250407152759.25160-3-ulf.hansson@linaro.org>
Date: Mon,  7 Apr 2025 17:27:52 +0200
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>,
	Avri Altman <Avri.Altman@...disk.com>,
	linux-renesas-soc@...r.kernel.org,
	linux-kernel@...r.kernel.org
Subject: [PATCH v2 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 prioritized option is to use the poweroff-notification command, if the
eMMC card supports it.

During a suspend request we may decide to fall back to use the sleep
command, instead of the poweroff-notification, unless the mmc host supports
a complete power-cycle of the eMMC. For this reason, we may need to restore
power and re-initialize the card, if it remains suspended when a shutdown
request is received.

However, the current condition to restore power and re-initialize the card
doesn't take into account MMC_CAP2_FULL_PWR_CYCLE_IN_SUSPEND properly. This
may lead to doing a re-initialization when it really isn't needed, as the
eMMC may already have been powered-off using the poweroff-notification
command. Let's fix the condition to avoid this.

Tested-by: Wolfram Sang <wsa+renesas@...g-engineering.com>
Signed-off-by: Ulf Hansson <ulf.hansson@...aro.org>
---

Changes in v2:
	- Updated commit message, clarified comment in the code and renamed a
	function, according to Wolfram/Avri's comments.

---
 drivers/mmc/core/mmc.c | 22 +++++++++++++++++-----
 1 file changed, 17 insertions(+), 5 deletions(-)

diff --git a/drivers/mmc/core/mmc.c b/drivers/mmc/core/mmc.c
index 3424bc9e20c5..ee65c5b85f95 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_host_can_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_host_can_poweroff_notify(host, is_suspend))
 		err = mmc_poweroff_notify(host->card, notify_type);
 	else if (mmc_can_sleep(host->card))
 		err = mmc_sleep(host);
@@ -2187,11 +2198,12 @@ static int mmc_shutdown(struct mmc_host *host)
 	int err = 0;
 
 	/*
-	 * In a specific case for poweroff notify, we need to resume the card
-	 * before we can shutdown it properly.
+	 * If the card remains suspended at this point and it was done by using
+	 * the sleep-cmd (CMD5), we may need to re-initialize it first, to allow
+	 * us to send the preferred poweroff-notification cmd at shutdown.
 	 */
 	if (mmc_can_poweroff_notify(host->card) &&
-		!(host->caps2 & MMC_CAP2_FULL_PWR_CYCLE))
+	    !mmc_host_can_poweroff_notify(host, true))
 		err = _mmc_resume(host);
 
 	if (!err)
-- 
2.43.0