[v3,3/6] mmc: core: refactor _mmc_suspend() for undervoltage handling

Commit Message

Oleksij Rempel Feb. 21, 2025, 9:39 a.m. UTC

Introduce an is_undervoltage parameter to _mmc_suspend() to apply a
short power-off sequence and optionally flush the cache. This refactoring
prepares for undervoltage support in a follow-up patch.

Signed-off-by: Oleksij Rempel <[e-mail]>
---
changes v3:
- add comments
- make sure _mmc_flush_cache is not executed in the undervoltage case
---
 drivers/mmc/core/mmc.c | 30 +++++++++++++++++++++---------
 1 file changed, 21 insertions(+), 9 deletions(-)

Patch

diff --git a/drivers/mmc/core/mmc.c b/drivers/mmc/core/mmc.c
index 6a23be214543..9270bde445ad 100644
--- a/drivers/mmc/core/mmc.c
+++ b/drivers/mmc/core/mmc.c
@@ -2104,20 +2104,32 @@  static int _mmc_flush_cache(struct mmc_host *host)
 	return err;
 }
 
-static int _mmc_suspend(struct mmc_host *host, bool is_suspend)
+static int _mmc_suspend(struct mmc_host *host, bool is_suspend,
+			bool is_undervoltage)
 {
+	unsigned int notify_type;
 	int err = 0;
-	unsigned int notify_type = is_suspend ? EXT_CSD_POWER_OFF_SHORT :
-					EXT_CSD_POWER_OFF_LONG;
+
+	/* In case of undervoltage, we don't have much time, so use short. */
+	if (is_undervoltage || is_suspend)
+		notify_type = EXT_CSD_POWER_OFF_SHORT;
+	else
+		notify_type = EXT_CSD_POWER_OFF_LONG;
 
 	mmc_claim_host(host);
 
 	if (mmc_card_suspended(host->card))
 		goto out;
 
-	err = _mmc_flush_cache(host);
-	if (err)
-		goto out;
+	/*
+	 * For the undervoltage case, we care more about device integrity.
+	 * Avoid cache flush and notify the device to power off quickly.
+	 */
+	if (!is_undervoltage) {
+		err = _mmc_flush_cache(host);
+		if (err)
+			goto out;
+	}
 
 	if (mmc_can_poweroff_notify(host->card) &&
 	    ((host->caps2 & MMC_CAP2_FULL_PWR_CYCLE) || !is_suspend ||
@@ -2144,7 +2156,7 @@  static int mmc_suspend(struct mmc_host *host)
 {
 	int err;
 
-	err = _mmc_suspend(host, true);
+	err = _mmc_suspend(host, true, false);
 	if (!err) {
 		pm_runtime_disable(&host->card->dev);
 		pm_runtime_set_suspended(&host->card->dev);
@@ -2191,7 +2203,7 @@  static int mmc_shutdown(struct mmc_host *host)
 		err = _mmc_resume(host);
 
 	if (!err)
-		err = _mmc_suspend(host, false);
+		err = _mmc_suspend(host, false, false);
 
 	return err;
 }
@@ -2215,7 +2227,7 @@  static int mmc_runtime_suspend(struct mmc_host *host)
 	if (!(host->caps & MMC_CAP_AGGRESSIVE_PM))
 		return 0;
 
-	err = _mmc_suspend(host, true);
+	err = _mmc_suspend(host, true, false);
 	if (err)
 		pr_err("%s: error %d doing aggressive suspend\n",
 			mmc_hostname(host), err);