scsi: ufs: Re-enable WriteBooster after device reset

UFS 3.1 specification mentions that the WriteBooster flags listed below
will be set to their default values, i.e. disabled, after power cycle or
any type of reset event. Thus we need to reset the flag variables kept in
struct hba to align with the device status and ensure that
WriteBooster-related functions are configured properly after device reset.

Without this fix, WriteBooster will not be enabled successfully after by
ufshcd_wb_ctrl() after device reset because hba->wb_enabled remains true.

Flags required to be reset to default values:

 - fWriteBoosterEn: hba->wb_enabled

 - fWriteBoosterBufferFlushEn: hba->wb_buf_flush_enabled

 - fWriteBoosterBufferFlushDuringHibernate: No variable mapped

Link: https://lore.kernel.org/r/20201208135635.15326-2-stanley.chu@mediatek.com
Fixes: 3d17b9b5 ("scsi: ufs: Add write booster feature support")
Reviewed-by: Bean Huo <beanhuo@micron.com>
Signed-off-by: Stanley Chu <stanley.chu@mediatek.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>

drivers/scsi/ufs/ufshcd.h

@@ -1221,8 +1221,13 @@ static inline void ufshcd_vops_device_reset(struct ufs_hba *hba)
 	if (hba->vops && hba->vops->device_reset) {
 		int err = hba->vops->device_reset(hba);
 
-		if (!err)
+		if (!err) {
 			ufshcd_set_ufs_dev_active(hba);
+			if (ufshcd_is_wb_allowed(hba)) {
+				hba->wb_enabled = false;
+				hba->wb_buf_flush_enabled = false;
+			}
+		}
 		if (err != -EOPNOTSUPP)
 			ufshcd_update_evt_hist(hba, UFS_EVT_DEV_RESET, err);
 	}