[PATCH 4.19 053/114] scsi: ufs: Fix error handing during hibern8 enter

From: Greg Kroah-Hartman
Date: Thu Jan 02 2020 - 17:53:40 EST

From: Subhash Jadavani <subhashj@xxxxxxxxxxxxxx>

[ Upstream commit 6d303e4b19d694cdbebf76bcdb51ada664ee953d ]

During clock gating (ufshcd_gate_work()), we first put the link hibern8 by
calling ufshcd_uic_hibern8_enter() and if ufshcd_uic_hibern8_enter()
returns success (0) then we gate all the clocks. Now letâs zoom in to what
ufshcd_uic_hibern8_enter() does internally: It calls
__ufshcd_uic_hibern8_enter() and if failure is encountered, link recovery
shall put the link back to the highest HS gear and returns success (0) to
ufshcd_uic_hibern8_enter() which is the issue as link is still in active
state due to recovery! Now ufshcd_uic_hibern8_enter() returns success to
ufshcd_gate_work() and hence it goes ahead with gating the UFS clock while
link is still in active state hence I believe controller would raise UIC
error interrupts. But when we service the interrupt, clocks might have
already been disabled!

This change fixes for this by returning failure from
__ufshcd_uic_hibern8_enter() if recovery succeeds as link is still not in
hibern8, upon receiving the error ufshcd_hibern8_enter() would initiate
retry to put the link state back into hibern8.

Link: https://lore.kernel.org/r/1573798172-20534-8-git-send-email-cang@xxxxxxxxxxxxxx
Reviewed-by: Avri Altman <avri.altman@xxxxxxx>
Reviewed-by: Bean Huo <beanhuo@xxxxxxxxxx>
Signed-off-by: Subhash Jadavani <subhashj@xxxxxxxxxxxxxx>
Signed-off-by: Can Guo <cang@xxxxxxxxxxxxxx>
Signed-off-by: Martin K. Petersen <martin.petersen@xxxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
drivers/scsi/ufs/ufshcd.c | 19 ++++++++++++++-----
1 file changed, 14 insertions(+), 5 deletions(-)

diff --git a/drivers/scsi/ufs/ufshcd.c b/drivers/scsi/ufs/ufshcd.c
index 7510d8328d4d..3601e770da16 100644
--- a/drivers/scsi/ufs/ufshcd.c
+++ b/drivers/scsi/ufs/ufshcd.c
@@ -3875,15 +3875,24 @@ static int __ufshcd_uic_hibern8_enter(struct ufs_hba *hba)
ktime_to_us(ktime_sub(ktime_get(), start)), ret);

if (ret) {
+ int err;
dev_err(hba->dev, "%s: hibern8 enter failed. ret = %d\n",
__func__, ret);

- * If link recovery fails then return error so that caller
- * don't retry the hibern8 enter again.
+ * If link recovery fails then return error code returned from
+ * ufshcd_link_recovery().
+ * If link recovery succeeds then return -EAGAIN to attempt
+ * hibern8 enter retry again.
- if (ufshcd_link_recovery(hba))
- ret = -ENOLINK;
+ err = ufshcd_link_recovery(hba);
+ if (err) {
+ dev_err(hba->dev, "%s: link recovery failed", __func__);
+ ret = err;
+ } else {
+ ret = -EAGAIN;
+ }
} else
ufshcd_vops_hibern8_notify(hba, UIC_CMD_DME_HIBER_ENTER,
@@ -3897,7 +3906,7 @@ static int ufshcd_uic_hibern8_enter(struct ufs_hba *hba)

for (retries = UIC_HIBERN8_ENTER_RETRIES; retries > 0; retries--) {
ret = __ufshcd_uic_hibern8_enter(hba);
- if (!ret || ret == -ENOLINK)
+ if (!ret)
goto out;