[PATCH v2] scsi: ufs: correct ufshcd_shutdown flow

[PATCH v2] scsi: ufs: correct ufshcd_shutdown flow

[peter.wang]

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

Both ufshcd_shtdown and ufshcd_wl_shutdown could run concurrently.
And it have race condition when ufshcd_wl_shutdown on-going and
clock/power turn off by ufshcd_shutdown.

The normal case:
ufshcd_wl_shutdown -> ufshcd_shtdown
ufshcd_shtdown should turn off clock/power.

The abnormal case:
ufshcd_shtdown -> ufshcd_wl_shutdown
Wait ufshcd_wl_shutdown set device to power off and turn off clock/power.
If timeout happen, means device still in active mode, cannot turn off
clock/power directly. Skip and keep clock/power on in this case.

Also remove pm_runtime_get_sync because shutdown is focus on
turn off clock/power. We don't need turn on(resume) and turn off.
The second reason is ufshcd_wl_shutdown call ufshcd_rpm_get_sync
already, if ufshcd_shtdown wait ufshcd_wl_shutdown finish,
hba->dev is already resume and no need pm_runtime_get_sync.

Signed-off-by: Peter Wang <peter.wang@mediatek.com>
---
 drivers/ufs/core/ufshcd.c | 14 +++++++++++---
 1 file changed, 11 insertions(+), 3 deletions(-)

diff --git a/drivers/ufs/core/ufshcd.c b/drivers/ufs/core/ufshcd.c
index c7b337480e3e..533563a2a6b7 100644
--- a/drivers/ufs/core/ufshcd.c
+++ b/drivers/ufs/core/ufshcd.c
@@ -58,6 +58,9 @@
 /* Task management command timeout */
 #define TM_CMD_TIMEOUT	100 /* msecs */
 
+/* Shutdown wait devcie into power off timeout */
+#define UFS_SHUTDWON_TIMEOUT	500 /* msecs */
+
 /* maximum number of retries for a general UIC command  */
 #define UFS_UIC_COMMAND_RETRIES 3
 
@@ -9461,10 +9464,15 @@ EXPORT_SYMBOL(ufshcd_runtime_resume);
  */
 int ufshcd_shutdown(struct ufs_hba *hba)
 {
-	if (ufshcd_is_ufs_dev_poweroff(hba) && ufshcd_is_link_off(hba))
-		goto out;
+	unsigned long timeout;
 
-	pm_runtime_get_sync(hba->dev);
+	/* Wait ufshcd_wl_shutdown clear ufs state */
+	timeout = jiffies + msecs_to_jiffies(UFS_SHUTDWON_TIMEOUT);
+	while (!ufshcd_is_ufs_dev_poweroff(hba) || !ufshcd_is_link_off(hba)) {
+		if (time_after(jiffies, timeout))
+			goto out;
+		msleep(1);
+	}
 
 	ufshcd_suspend(hba);
 out:
-- 
2.18.0