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

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Message-ID: <DM6PR04MB6575A7FE015D8690F5094957FC2A9@DM6PR04MB6575.namprd04.prod.outlook.com>
Date:   Thu, 20 Oct 2022 07:16:38 +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 RESEND] 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>
> ---
>  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?

> +
>         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