[PATCH v1 6/6] scsi: ufs: Fix error handing during hibern8 enter

Can Guo
2019-11-02T05:06:03Z

From: Subhash Jadavani <subhashj@codeaurora.org>

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 let’s zoom in to what ufshcd_uic_hibern8_enter() does internally:
It calls __ufshcd_uic_hibern8_enter() which on detecting the LINERESET,
initiates the full recovery and puts the link back to 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.

Signed-off-by: Subhash Jadavani <subhashj@codeaurora.org>
Signed-off-by: Can Guo <cang@codeaurora.org>
---
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 c9ef2dd..1201578 100644
--- a/drivers/scsi/ufs/ufshcd.c
+++ b/drivers/scsi/ufs/ufshcd.c
@@ -3891,15 +3891,24 @@ 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 (-ENOLINK)
+ * returned 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,
POST_CHANGE);
@@ -3913,7 +3922,7 @@ 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;
}