Messages in this thread | | | Date | Wed, 29 Jul 2020 13:31:40 +0800 | From | Can Guo <> | Subject | Re: [PATCH v1 1/2] scsi: ufs: Introduce device quirk "DELAY_AFTER_LPM" |
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Hi Stanley,
On 2020-07-29 13:18, Stanley Chu wrote: > Some UFS devices require delay after VCC power rail is turned-off. > Introduce a device quirk "DELAY_AFTER_LPM" to add 5ms delays after > VCC power-off during suspend flow. >
Just curious, I can understand if you want to add some delays before turnning off VCC/VCCQ/VCCQ2, but what is the delay AFTER turnning them off for? I mean the power has been cut by host from PMIC, how can the delay benefit the UFS device?
Thanks,
Can Guo.
> Signed-off-by: Andy Teng <andy.teng@mediatek.com> > Signed-off-by: Peter Wang <peter.wang@mediatek.com> > Signed-off-by: Stanley Chu <stanley.chu@mediatek.com> > --- > drivers/scsi/ufs/ufs_quirks.h | 7 +++++++ > drivers/scsi/ufs/ufshcd.c | 11 +++++++++++ > 2 files changed, 18 insertions(+) > > diff --git a/drivers/scsi/ufs/ufs_quirks.h > b/drivers/scsi/ufs/ufs_quirks.h > index 2a0041493e30..07f559ac5883 100644 > --- a/drivers/scsi/ufs/ufs_quirks.h > +++ b/drivers/scsi/ufs/ufs_quirks.h > @@ -109,4 +109,11 @@ struct ufs_dev_fix { > */ > #define UFS_DEVICE_QUIRK_SUPPORT_EXTENDED_FEATURES (1 << 10) > > +/* > + * Some UFS devices require delay after VCC power rail is turned-off. > + * Enable this quirk to introduce 5ms delays after VCC power-off > during > + * suspend flow. > + */ > +#define UFS_DEVICE_QUIRK_DELAY_AFTER_LPM (1 << 11) > + > #endif /* UFS_QUIRKS_H_ */ > diff --git a/drivers/scsi/ufs/ufshcd.c b/drivers/scsi/ufs/ufshcd.c > index acba2271c5d3..63f4e2f75aa1 100644 > --- a/drivers/scsi/ufs/ufshcd.c > +++ b/drivers/scsi/ufs/ufshcd.c > @@ -8111,6 +8111,8 @@ static int ufshcd_link_state_transition(struct > ufs_hba *hba, > > static void ufshcd_vreg_set_lpm(struct ufs_hba *hba) > { > + bool vcc_off = false; > + > /* > * It seems some UFS devices may keep drawing more than sleep current > * (atleast for 500us) from UFS rails (especially from VCCQ rail). > @@ -8139,13 +8141,22 @@ static void ufshcd_vreg_set_lpm(struct ufs_hba > *hba) > if (ufshcd_is_ufs_dev_poweroff(hba) && ufshcd_is_link_off(hba) && > !hba->dev_info.is_lu_power_on_wp) { > ufshcd_setup_vreg(hba, false); > + vcc_off = true; > } else if (!ufshcd_is_ufs_dev_active(hba)) { > ufshcd_toggle_vreg(hba->dev, hba->vreg_info.vcc, false); > + vcc_off = true; > if (!ufshcd_is_link_active(hba)) { > ufshcd_config_vreg_lpm(hba, hba->vreg_info.vccq); > ufshcd_config_vreg_lpm(hba, hba->vreg_info.vccq2); > } > } > + > + /* > + * Some UFS devices require delay after VCC power rail is turned-off. > + */ > + if (vcc_off && hba->vreg_info.vcc && > + hba->dev_quirks & UFS_DEVICE_QUIRK_DELAY_AFTER_LPM) > + usleep_range(5000, 5100); > } > > static int ufshcd_vreg_set_hpm(struct ufs_hba *hba)
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