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scsi: ufs: optimize system suspend handling

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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>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
This commit is contained in:
subhashj@codeaurora.org 2016-11-23 16:33:08 -08:00 committed by Martin K. Petersen
parent f37e9f8cf8
commit 0b25773434
1 changed files with 6 additions and 9 deletions
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15
drivers/scsi/ufs/ufshcd.c
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@ -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