Commit 6d303e4b authored Nov 14, 2019 by Subhash Jadavani Committed by Martin K. Petersen Nov 19, 2019

scsi: ufs: Fix error handing during hibern8 enter

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() 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@codeaurora.org


Reviewed-by: Avri Altman <avri.altman@wdc.com>
Reviewed-by: Bean Huo <beanhuo@micron.com>
Signed-off-by: Subhash Jadavani <subhashj@codeaurora.org>
Signed-off-by: Can Guo <cang@codeaurora.org>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>

parent 18f01374

drivers/scsi/ufs/ufshcd.c

+14 −5

Original line number	Diff line number	Diff line
		@@ -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 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,
		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;
		}
		out:

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