2020-02-11 03:50:26

by Can Guo

Subject: [PATCH v10 1/7] scsi: ufs: Flush exception event before suspend

From: Sayali Lokhande <[email protected]>

Exception event can be raised by the device when system
suspend is in progress. This will result in unclocked
register access in exception event handler as clocks will
be turned off during suspend. This change makes sure to flush
exception event handler work in suspend before disabling
clocks to avoid unclocked register access issue.

Signed-off-by: Sayali Lokhande <[email protected]>
Signed-off-by: Asutosh Das <[email protected]>
Signed-off-by: Can Guo <[email protected]>
Reviewed-by: Bean Huo <[email protected]>
---
drivers/scsi/ufs/ufshcd.c | 21 ++++++++++++++++++---
1 file changed, 18 insertions(+), 3 deletions(-)

diff --git a/drivers/scsi/ufs/ufshcd.c b/drivers/scsi/ufs/ufshcd.c
index abd0e6b..10dbc0c 100644
--- a/drivers/scsi/ufs/ufshcd.c
+++ b/drivers/scsi/ufs/ufshcd.c
@@ -4730,8 +4730,15 @@ static void ufshcd_slave_destroy(struct scsi_device *sdev)
* UFS device needs urgent BKOPs.
*/
if (!hba->pm_op_in_progress &&
- ufshcd_is_exception_event(lrbp->ucd_rsp_ptr))
- schedule_work(&hba->eeh_work);
+ ufshcd_is_exception_event(lrbp->ucd_rsp_ptr) &&
+ schedule_work(&hba->eeh_work)) {
+ /*
+ * Prevent suspend once eeh_work is scheduled
+ * to avoid deadlock between ufshcd_suspend
+ * and exception event handler.
+ */
+ pm_runtime_get_noresume(hba->dev);
+ }
break;
case UPIU_TRANSACTION_REJECT_UPIU:
/* TODO: handle Reject UPIU Response */
@@ -5184,7 +5191,14 @@ static void ufshcd_exception_event_handler(struct work_struct *work)

out:
ufshcd_scsi_unblock_requests(hba);
- pm_runtime_put_sync(hba->dev);
+ /*
+ * pm_runtime_get_noresume is called while scheduling
+ * eeh_work to avoid suspend racing with exception work.
+ * Hence decrement usage counter using pm_runtime_put_noidle
+ * to allow suspend on completion of exception event handler.
+ */
+ pm_runtime_put_noidle(hba->dev);
+ pm_runtime_put(hba->dev);
return;
}

@@ -7924,6 +7938,7 @@ static int ufshcd_suspend(struct ufs_hba *hba, enum ufs_pm_op pm_op)
goto enable_gating;
}

+ flush_work(&hba->eeh_work);
ret = ufshcd_link_state_transition(hba, req_link_state, 1);
if (ret)
goto set_dev_active;
--
The Qualcomm Innovation Center, Inc. is a member of the Code Aurora Forum,
a Linux Foundation Collaborative Project

2020-02-14 02:50:29

by hongwus

Subject: Re: [PATCH v10 1/7] scsi: ufs: Flush exception event before suspend

On 2020-02-11 11:40, Can Guo wrote:
> From: Sayali Lokhande <[email protected]>
>
> Exception event can be raised by the device when system
> suspend is in progress. This will result in unclocked
> register access in exception event handler as clocks will
> be turned off during suspend. This change makes sure to flush
> exception event handler work in suspend before disabling
> clocks to avoid unclocked register access issue.
>
> Signed-off-by: Sayali Lokhande <[email protected]>
> Signed-off-by: Asutosh Das <[email protected]>
> Signed-off-by: Can Guo <[email protected]>
> Reviewed-by: Bean Huo <[email protected]>


Reviewed-by: Hongwu Su <[email protected]>