[PATCH v1] scsi: ufs: clear doorbell for hibern8 errors when using ah8

[Kiwoong Kim]

When an scsi command is dispatched right after host complete
all the pending requests goes to idle and ufs driver tries
to ring a doorbell, host might be still during entering into
hibern8. If an error occurrs during that period, the doorbell
might not be zero. In this case, clearing it should be needed
to requeue its command.
Currently, ufshcd_err_handler goes directly to reset when the
driver's link state is broken. This patch is to make it clear
doorbells in the case. In the situation, communication would
be disabled, so TM isn't necessary or we can say it's not
available.

Here's an actual symptom that I've faced. At the time, tag #17
is still pended even after host reset. And then the block timer
is expired.

exynos-ufs 11100000.ufs: ufshcd_check_errors: Auto Hibern8
Enter failed - status: 0x00000040, upmcrs: 0x00000001
..
host_regs: 00000050: b8671000 00000008 00020000 00000000
..
exynos-ufs 11100000.ufs: ufshcd_abort: Device abort task at tag 17

Signed-off-by: Kiwoong Kim <kwmad.kim@xxxxxxxxxxx>
---
 drivers/scsi/ufs/ufshcd.c | 11 ++++++++++-
 1 file changed, 10 insertions(+), 1 deletion(-)

diff --git a/drivers/scsi/ufs/ufshcd.c b/drivers/scsi/ufs/ufshcd.c
index 9faf02c..13f406d 100644
--- a/drivers/scsi/ufs/ufshcd.c
+++ b/drivers/scsi/ufs/ufshcd.c
@@ -6076,6 +6076,7 @@ static void ufshcd_err_handler(struct Scsi_Host *host)
 	int err = 0, pmc_err;
 	int tag;
 	bool needs_reset = false, needs_restore = false;
+	bool link_broken_in_ah8 = false;
 
 	down(&hba->host_sem);
 	spin_lock_irqsave(hba->host->host_lock, flags);
@@ -6138,7 +6139,12 @@ static void ufshcd_err_handler(struct Scsi_Host *host)
 	     (hba->saved_uic_err & (UFSHCD_UIC_DL_NAC_RECEIVED_ERROR |
 				    UFSHCD_UIC_DL_TCx_REPLAY_ERROR)))) {
 		needs_reset = true;
-		goto do_reset;
+		spin_lock_irqsave(hba->host->host_lock, flags);
+		if (!hba->ahit && ufshcd_is_link_broken(hba))
+			link_broken_in_ah8 = true;
+		spin_unlock_irqrestore(hba->host->host_lock, flags);
+		if (!link_broken_in_ah8)
+			goto do_reset;
 	}
 
 	/*
@@ -6168,6 +6174,9 @@ static void ufshcd_err_handler(struct Scsi_Host *host)
 		}
 	}
 
+	if (link_broken_in_ah8)
+		goto lock_skip_pending_xfer_clear;
+
 	/* Clear pending task management requests */
 	for_each_set_bit(tag, &hba->outstanding_tasks, hba->nutmrs) {
 		if (ufshcd_clear_tm_cmd(hba, tag)) {
-- 
2.7.4