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scsi: ufs: add delay before putting UFS rails in low power modes

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We put the UFS device in sleep state & UFS link in hibern8 state during
runtime suspaned. After this we put all the UFS rails in low power
modes immediately but it seems some devices may still draw more than sleep
current from UFS rails (especially from VCCQ rail) atleast for 500us.
To avoid this situation, this change adds 2ms delay before putting these
UFS rails in LPM mode.

Change-Id: Ifd8d3ef9e059f527613af0fcaa25ec2a282ad6c4
Signed-off-by: Subhash Jadavani <subhashj@codeaurora.org>
This commit is contained in:
Subhash Jadavani 2015-05-27 16:26:00 -07:00 • committed by David Keitel
parent 8c62c80743
commit 6517fb12c8
1 changed files with 9 additions and 0 deletions
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9
drivers/scsi/ufs/ufshcd.c
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@ -7559,6 +7559,15 @@ out:
static void ufshcd_vreg_set_lpm(struct ufs_hba *hba)
{
/*
* It seems some UFS devices may keep drawing more than sleep current
* (atleast for 500us) from UFS rails (especially from VCCQ rail).
* To avoid this situation, add 2ms delay before putting these UFS
* rails in LPM mode.
*/
if (!ufshcd_is_link_active(hba))
usleep_range(2000, 2100);
/*
* If UFS device is either in UFS_Sleep turn off VCC rail to save some
* power.