linux-kernel - Re: [PATCH V2] scsi: ufs: core: Let delay value after LPM can be modified by vendor

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Date:   Sun, 23 Oct 2022 18:18:42 +0800
From:   Zhe Wang <zhewang116@...il.com>
To:     Avri Altman <Avri.Altman@....com>
Cc:     "jejb@...ux.ibm.com" <jejb@...ux.ibm.com>,
        "martin.petersen@...cle.com" <martin.petersen@...cle.com>,
        "alim.akhtar@...sung.com" <alim.akhtar@...sung.com>,
        "bvanassche@....org" <bvanassche@....org>,
        "linux-scsi@...r.kernel.org" <linux-scsi@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "beanhuo@...ron.com" <beanhuo@...ron.com>,
        "stanley.chu@...iatek.com" <stanley.chu@...iatek.com>,
        "adrian.hunter@...el.com" <adrian.hunter@...el.com>,
        "zhe.wang1@...soc.com" <zhe.wang1@...soc.com>,
        "zhenxiong.lai@...soc.com" <zhenxiong.lai@...soc.com>,
        "yuelin.tang@...soc.com" <yuelin.tang@...soc.com>
Subject: Re: [PATCH V2] scsi: ufs: core: Let delay value after LPM can be
 modified by vendor

> > From: Zhe Wang <zhe.wang1@...soc.com>
> >
> > Some UFS devices require that the VCC should drop below 0.1V after
> > turning off, otherwise device may not resume successfully. And
> > because the power-off rate is different on different SOC platforms.
> > Therefore, we hope that the delay can be modified by vendor to
> > adjust the most appropriate delay value.
> >
> > Signed-off-by: Zhe Wang <zhe.wang1@...soc.com>
> > ---
> > V1 -> V2
> > - move turnoff_delay_us to struct ufs_vreg instead
> > - replace usleep_range with ufshcd_delay_us
> >
> >  drivers/ufs/core/ufshcd.c | 9 ++++++++-
> >  include/ufs/ufs.h         | 1 +
> >  2 files changed, 9 insertions(+), 1 deletion(-)
> >
> > diff --git a/drivers/ufs/core/ufshcd.c b/drivers/ufs/core/ufshcd.c
> > index 7256e6c43ca6..386ff6ed2f20 100644
> > --- a/drivers/ufs/core/ufshcd.c
> > +++ b/drivers/ufs/core/ufshcd.c
> > @@ -89,6 +89,9 @@
> >  /* Polling time to wait for fDeviceInit */
> >  #define FDEVICEINIT_COMPL_TIMEOUT 1500 /* millisecs */
> >
> > +/* Default value of turn off VCC rail: 5000us */
> > +#define UFS_VCC_TURNOFF_DELAY_US 5000
> > +
> >  #define ufshcd_toggle_vreg(_dev, _vreg, _on)                           \
> >         ({                                                              \
> >                 int _ret;                                               \
> > @@ -7784,6 +7787,10 @@ static int ufs_get_device_desc(struct ufs_hba *hba)
> >
> >         ufs_fixup_device_setup(hba);
> >
> > +       if (hba->dev_quirks & UFS_DEVICE_QUIRK_DELAY_AFTER_LPM &&
> > +           !hba->vreg_info.vcc->turnoff_delay_us)
> > +               hba->vreg_info.vcc->turnoff_delay_us =
> > UFS_VCC_TURNOFF_DELAY_US;
> > +
> You answered my question to your v1 - where otherwise you are setting this value:
> "We are still preparing and discussing our own UFS host driver code,
> which will be uploaded once we are done."
>
> Well until then - this isn't very useful.
>
> Thanks,
> Avri
>
> >         ufshcd_wb_probe(hba, desc_buf);
> >
> >         ufshcd_temp_notif_probe(hba, desc_buf);
> > @@ -8918,7 +8925,7 @@ static void ufshcd_vreg_set_lpm(struct ufs_hba *hba)
> >          */
> >         if (vcc_off && hba->vreg_info.vcc &&
> >                 hba->dev_quirks & UFS_DEVICE_QUIRK_DELAY_AFTER_LPM)
> > -               usleep_range(5000, 5100);
> > +               ufshcd_delay_us(hba->vreg_info.vcc->turnoff_delay_us, 100);
> >  }
> >
> >  #ifdef CONFIG_PM
> > diff --git a/include/ufs/ufs.h b/include/ufs/ufs.h
> > index 1bba3fead2ce..792335dfd70b 100644
> > --- a/include/ufs/ufs.h
> > +++ b/include/ufs/ufs.h
> > @@ -569,6 +569,7 @@ struct ufs_vreg {
> >         bool always_on;
> >         bool enabled;
> >         int max_uA;
> > +       u32 turnoff_delay_us;
> >  };
> >
> >  struct ufs_vreg_info {
> > --
> > 2.17.1
>

OK, thanks for your review.

Thanks,
Zhe Wang