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    SubjectRe: [PATCH v1 16/17] scsi: ufs: add delay before putting UFS rails in low power modes
    From
    2015-09-13 23:52 GMT+09:00 Yaniv Gardi <ygardi@codeaurora.org>:
    > 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.
    >
    > Signed-off-by: Subhash Jadavani <subhashj@codeaurora.org>
    > Signed-off-by: Yaniv Gardi <ygardi@codeaurora.org>
    >
    > ---
    > drivers/scsi/ufs/ufshcd.c | 9 +++++++++
    > 1 file changed, 9 insertions(+)
    >
    > diff --git a/drivers/scsi/ufs/ufshcd.c b/drivers/scsi/ufs/ufshcd.c
    > index 20b4c0e..786df28 100644
    > --- a/drivers/scsi/ufs/ufshcd.c
    > +++ b/drivers/scsi/ufs/ufshcd.c
    > @@ -5694,6 +5694,15 @@ 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);
    > +

    Shouldn't we define dev_quirks for this?

    > + /*
    > * If UFS device is either in UFS_Sleep turn off VCC rail to save some
    > * power.
    > *
    > --
    > 1.8.5.2
    >
    > --
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