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

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Date:   Fri, 21 Oct 2022 07:46:47 +0000
From:   Avri Altman <Avri.Altman@....com>
To:     Zhe Wang <zhewang116@...il.com>,
        "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>
CC:     "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