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Subject[PATCH v1 10/11] scsi: ufs: optimize system suspend handling
Date
Consider following sequence of events:
1. UFS is runtime suspended, link_state = Hibern8, device_state = sleep
2. System goes into system suspend, ufshcd_system_suspend() brings both
link and device to active state and then puts the device in Power_Down
state and link in OFF state.
3. System resumes at some later point in time, ufshcd_system_resume()
doesn't do anything as UFS state is runtime suspended. Note that link
is still on OFF state and device is in Power_Down state.
4. Now system again goes into suspend without any UFS accesses before it.
ufshcd_system_suspend() again brings both link and device to active
state and then puts the device in Power_Down state and link if OFF
state. But it's unnecessary to bring the link & device in active state
as both link and device are already in desired low power states. This
change fixes this issue by adding proper state checks in
ufshcd_system_suspend().

Reviewed-by: Gilad Broner <gbroner@codeaurora.org>
Signed-off-by: Subhash Jadavani <subhashj@codeaurora.org>
---
drivers/scsi/ufs/ufshcd.c | 15 ++++++---------
1 file changed, 6 insertions(+), 9 deletions(-)

diff --git a/drivers/scsi/ufs/ufshcd.c b/drivers/scsi/ufs/ufshcd.c
index b826078..4b6cc07 100644
--- a/drivers/scsi/ufs/ufshcd.c
+++ b/drivers/scsi/ufs/ufshcd.c
@@ -6272,16 +6272,13 @@ int ufshcd_system_suspend(struct ufs_hba *hba)
if (!hba || !hba->is_powered)
return 0;

- if (pm_runtime_suspended(hba->dev)) {
- if (hba->rpm_lvl == hba->spm_lvl)
- /*
- * There is possibility that device may still be in
- * active state during the runtime suspend.
- */
- if ((ufs_get_pm_lvl_to_dev_pwr_mode(hba->spm_lvl) ==
- hba->curr_dev_pwr_mode) && !hba->auto_bkops_enabled)
- goto out;
+ if ((ufs_get_pm_lvl_to_dev_pwr_mode(hba->spm_lvl) ==
+ hba->curr_dev_pwr_mode) &&
+ (ufs_get_pm_lvl_to_link_pwr_state(hba->spm_lvl) ==
+ hba->uic_link_state))
+ goto out;

+ if (pm_runtime_suspended(hba->dev)) {
/*
* UFS device and/or UFS link low power states during runtime
* suspend seems to be different than what is expected during
--
The Qualcomm Innovation Center, Inc. is a member of the Code Aurora Forum,
a Linux Foundation Collaborative Project
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