[PATCH v2 03/17] scsi: ufs: optimize system suspend handling

From: Yaniv Gardi
Date: Mon Oct 26 2015 - 11:41:49 EST

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().

Signed-off-by: Subhash Jadavani <subhashj@xxxxxxxxxxxxxx>
Signed-off-by: Yaniv Gardi <ygardi@xxxxxxxxxxxxxx>

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 20c5b5d..00964f9 100644
--- a/drivers/scsi/ufs/ufshcd.c
+++ b/drivers/scsi/ufs/ufshcd.c
@@ -5459,16 +5459,13 @@ 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

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