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

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Date:   Thu, 20 Oct 2022 17:16:59 +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 RESEND] scsi: ufs: core: Let delay value after LPM can be
 modified by vendor

Avri Altman <Avri.Altman@....com> 于2022年10月20日周四 15:16写道：
>
> > 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>
> > ---
> >  drivers/ufs/core/ufshcd.c | 11 +++++++++--
> >  include/ufs/ufshcd.h      |  2 ++
> >  2 files changed, 11 insertions(+), 2 deletions(-)
> >
> > diff --git a/drivers/ufs/core/ufshcd.c b/drivers/ufs/core/ufshcd.c
> > index 7256e6c43ca6..f6350231da0e 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 +7787,9 @@ 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->vcc_turnoff_delay)
> > +               hba->vcc_turnoff_delay = UFS_VCC_TURNOFF_DELAY_US;
> Couldn't find where otherwise you are setting this value?
> Also, UFS_DEVICE_QUIRK_DELAY_AFTER_LPM is only set for MTK.
> Are you planning at some point adding your own host driver?
>

We are still preparing and discussing our own UFS host driver code,
which will be uploaded once we are done.

> > +
> >         ufshcd_wb_probe(hba, desc_buf);
> >
> >         ufshcd_temp_notif_probe(hba, desc_buf);
> > @@ -8917,8 +8923,9 @@ static void ufshcd_vreg_set_lpm(struct ufs_hba
> > *hba)
> >          * 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);
> > +               hba->dev_quirks & UFS_DEVICE_QUIRK_DELAY_AFTER_LPM &&
> > +               hba->vcc_turnoff_delay)
> > +               usleep_range(hba->vcc_turnoff_delay, hba->vcc_turnoff_delay +
> > 100);
> >  }
> >
> >  #ifdef CONFIG_PM
> > diff --git a/include/ufs/ufshcd.h b/include/ufs/ufshcd.h
> > index 9f28349ebcff..bfde3cb962fb 100644
> > --- a/include/ufs/ufshcd.h
> > +++ b/include/ufs/ufshcd.h
> > @@ -828,6 +828,7 @@ struct ufs_hba_monitor {
> >   *     device
> >   * @complete_put: whether or not to call ufshcd_rpm_put() from inside
> >   *     ufshcd_resume_complete()
> > + * @vcc_turnoff_delay: VCC turnoff delay value.
> >   */
> >  struct ufs_hba {
> >         void __iomem *mmio_base;
> > @@ -975,6 +976,7 @@ struct ufs_hba {
> >  #endif
> >         u32 luns_avail;
> >         bool complete_put;
> > +       u32 vcc_turnoff_delay;
> Can this be part of struct ufs_vreg instead?
> Also maybe vcc_turnoff_delay_us?
>
> Thanks,
> Avri
> >  };
> >
> >  /* Returns true if clocks can be gated. Otherwise false */
> > --
> > 2.17.1
>

Thanks for your suggestion, I will modify it in V2.

Thanks,
Zhe Wang