[PATCH] scsi: ufs: core: Reset urgent_bkops_lvl to allow runtime PM power mode

[Won Jung]

This patch ensures that UFS Runtime PM can achieve power saving
after System PM suspend by resetting hba->urgent_bkops_lvl.
It also modifies ufshcd_bkops_exception_event_handler to avoid
setting urgent_bkops_lvl when status is 0, which helps maintain
optimal power management.

On UFS devices supporting UFSHCD_CAP_AUTO_BKOPS_SUSPEND,
a BKOPS exception event can lead to a situation
where UFS Runtime PM can't enter low-power mode states even
after the BKOPS exception has been resolved.

BKOPS exception with bkops status 0 occurs, the driver logs:
"ufshcd_bkops_exception_event_handler:
device raised urgent BKOPS exception for bkops status 0"

When a BKOPS exception occurs, `ufshcd_bkops_exception_event_handler()`
reads the BKOPS status and sets `hba->urgent_bkops_lvl` to
BKOPS_STATUS_NO_OP(0). This allows the device to perform Runtime PM
without changing the UFS power mode.
(`__ufshcd_wl_suspend(hba, UFS_RUNTIME_PM)`)

During system PM suspend, `ufshcd_disable_auto_bkops()` is called,
disabling auto bkops. After UFS System PM Resume,
when runtime PM attempts to suspend again,
`ufshcd_urgent_bkops()` is invoked. Since `hba->urgent_bkops_lvl`
remains at BKOPS_STATUS_NO_OP(0), `ufshcd_enable_auto_bkops()`
is triggered.

However, in `ufshcd_bkops_ctrl()`,
the driver compares the current BKOPS status with
`hba->urgent_bkops_lvl`, and only enables auto bkops
if `curr_status >= hba->urgent_bkops_lvl`.
Since both values are 0, the condition is met

As a result, `__ufshcd_wl_suspend(hba, UFS_RUNTIME_PM)` skips power mode
transitions and remains in an active state, preventing power saving even
though no urgent BKOPS condition exists.

Signed-off-by: wone.jung <wone.jung@xxxxxxxxxxx>
---
 drivers/ufs/core/ufshcd.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/drivers/ufs/core/ufshcd.c b/drivers/ufs/core/ufshcd.c
index 604043a7533d..e2d3e834ccba 100644
--- a/drivers/ufs/core/ufshcd.c
+++ b/drivers/ufs/core/ufshcd.c
@@ -5959,6 +5959,7 @@ static int ufshcd_disable_auto_bkops(struct ufs_hba *hba)
 
 	hba->auto_bkops_enabled = false;
 	trace_ufshcd_auto_bkops_state(hba, "Disabled");
+	hba->urgent_bkops_lvl = BKOPS_STATUS_PERF_IMPACT;
 	hba->is_urgent_bkops_lvl_checked = false;
 out:
 	return err;
@@ -6062,7 +6063,7 @@ static void ufshcd_bkops_exception_event_handler(struct ufs_hba *hba)
 	 * impacted or critical. Handle these device by determining their urgent
 	 * bkops status at runtime.
 	 */
-	if (curr_status < BKOPS_STATUS_PERF_IMPACT) {
+	if ((curr_status > BKOPS_STATUS_NO_OP) && (curr_status < BKOPS_STATUS_PERF_IMPACT)) {
 		dev_err(hba->dev, "%s: device raised urgent BKOPS exception for bkops status %d\n",
 				__func__, curr_status);
 		/* update the current status as the urgent bkops level */
-- 
2.17.1