[PATCH v2 1/2] ufs: always notify POST_CHANGE even on gear switch failure

[peter.wang at mediatek.com]

From: Peter Wang <peter.wang at mediatek.com>

Previously, POST_CHANGE was only notified on a successful gear switch.
This could leave the host in an inconsistent state if resources were
acquired in PRE_CHANGE (e.g. disabling auto-hibern8) but never
released due to a missing POST_CHANGE.

Fix this by always calling POST_CHANGE regardless of the gear switch
result. On failure, pass dev_req_params = NULL to signal that there is
nothing to apply; hosts that receive NULL simply skip their post work.

Update the affected vendor drivers (ufs-exynos and ufshcd-pci) to
guard their POST_CHANGE logic with a NULL check so they correctly
handle the failure case.

Fixes: f5ca8d0c7a63 ("scsi: ufs: host: mediatek: Disable auto-hibern8 during power mode changes")
Signed-off-by: Peter Wang <peter.wang at mediatek.com>
---
 drivers/ufs/core/ufshcd.c     | 8 ++++++--
 drivers/ufs/host/ufs-exynos.c | 4 +++-
 drivers/ufs/host/ufshcd-pci.c | 3 ++-
 3 files changed, 11 insertions(+), 4 deletions(-)

diff --git a/drivers/ufs/core/ufshcd.c b/drivers/ufs/core/ufshcd.c
index 2ba244cf40ac..39a4bdafc1af 100644
--- a/drivers/ufs/core/ufshcd.c
+++ b/drivers/ufs/core/ufshcd.c
@@ -4979,8 +4979,12 @@ int ufshcd_change_power_mode(struct ufs_hba *hba,
 
 	ret = ufshcd_dme_change_power_mode(hba, pwr_mode, pmc_policy);
 
-	if (!ret)
-		ufshcd_vops_pwr_change_notify(hba, POST_CHANGE, pwr_mode);
+	/*
+	 * Always notify POST_CHANGE to pair with PRE_CHANGE, even on failure.
+	 * On failure, pass dev_req_params = NULL to indicate nothing to apply.
+	 * POST_CHANGE return value is advisory and does not mask @ret.
+	 */
+	ufshcd_vops_pwr_change_notify(hba, POST_CHANGE, ret ? NULL : pwr_mode);
 
 	return ret;
 }
diff --git a/drivers/ufs/host/ufs-exynos.c b/drivers/ufs/host/ufs-exynos.c
index b2f65c465525..3bcbc9ebbb28 100644
--- a/drivers/ufs/host/ufs-exynos.c
+++ b/drivers/ufs/host/ufs-exynos.c
@@ -1782,7 +1782,9 @@ static int exynos_ufs_pwr_change_notify(struct ufs_hba *hba,
 		ret = exynos_ufs_pre_pwr_mode(hba, dev_req_params);
 		break;
 	case POST_CHANGE:
-		ret = exynos_ufs_post_pwr_mode(hba, dev_req_params);
+		/* NULL when the gear switch failed: nothing to apply */
+		if (dev_req_params)
+			ret = exynos_ufs_post_pwr_mode(hba, dev_req_params);
 		break;
 	}
 
diff --git a/drivers/ufs/host/ufshcd-pci.c b/drivers/ufs/host/ufshcd-pci.c
index 21bb11c724be..668b57403e62 100644
--- a/drivers/ufs/host/ufshcd-pci.c
+++ b/drivers/ufs/host/ufshcd-pci.c
@@ -166,7 +166,8 @@ static int ufs_intel_lkf_pwr_change_notify(struct ufs_hba *hba,
 			ufs_intel_set_lanes(hba, 2);
 		break;
 	case POST_CHANGE:
-		if (ufshcd_is_hs_mode(dev_req_params)) {
+		/* NULL when the gear switch failed: nothing to apply */
+		if (dev_req_params && ufshcd_is_hs_mode(dev_req_params)) {
 			u32 peer_granularity;
 
 			usleep_range(1000, 1250);
-- 
2.45.2