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

Ensures that UFS Runtime PM can achieve power saving after System PM
suspend by resetting hba->urgent_bkops_lvl. Also modify the
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: Won Jung <wone.jung@samsung.com>
Reviewed-by: Peter Wang <peter.wang@mediatek.com>
Link: https://patch.msgid.link/1891546521.01770806581968.JavaMail.epsvc@epcpadp2new
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>

diff --git a/drivers/ufs/core/ufshcd.c b/drivers/ufs/core/ufshcd.c
index 12f1bdc705877a985a26592ae9afc1d32da4b8a7..3bbc2b51c87bf1648c9187107c0b6df609140f0d 100644 (file)
--- a/drivers/ufs/core/ufshcd.c
+++ b/drivers/ufs/core/ufshcd.c
@@ -5982,6 +5982,7 @@ 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;
@@ -6085,7 +6086,7 @@ 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 */