RE: [PATCH RFC v4 1/1] scsi: ufs: Fix ufs power down/on specs violation

[Avri Altman]

Hi,
> 
> As per specs, e.g, JESD220E chapter 7.2, while powering
> off/on the ufs device, RST_N signal and REF_CLK signal
> should be between VSS(Ground) and VCCQ/VCCQ2.
> 
> To flexibly control device reset line, refactor the function
> ufschd_vops_device_reset(sturct ufs_hba *hba) to ufshcd_
> vops_device_reset(sturct ufs_hba *hba, bool asserted). The
> new parameter "bool asserted" is used to separate device reset
> line pulling down from pulling up.
Sorry for my late response.
Please allow few more days to consult internally about this. 

> 
> Cc: Kiwoong Kim <kwmad.kim@xxxxxxxxxxx>
> Cc: Stanley Chu <stanley.chu@xxxxxxxxxxxx>
> Signed-off-by: Ziqi Chen <ziqichen@xxxxxxxxxxxxxx>


> -static int ufs_qcom_device_reset(struct ufs_hba *hba)
> +static int ufs_qcom_device_reset(struct ufs_hba *hba, bool asserted)
>  {
>         struct ufs_qcom_host *host = ufshcd_get_variant(hba);
> 
> @@ -1417,15 +1418,20 @@ static int ufs_qcom_device_reset(struct ufs_hba
> *hba)
>         if (!host->device_reset)
>                 return -EOPNOTSUPP;
> 
> -       /*
> -        * The UFS device shall detect reset pulses of 1us, sleep for 10us to
> -        * be on the safe side.
> -        */
> -       gpiod_set_value_cansleep(host->device_reset, 1);
> -       usleep_range(10, 15);
> +       if (asserted) {
> +               gpiod_set_value_cansleep(host->device_reset, 1);
> 
> -       gpiod_set_value_cansleep(host->device_reset, 0);
> -       usleep_range(10, 15);
> +               /*
> +                * The UFS device shall detect reset pulses of 1us, sleep for 10us to
> +                * be on the safe side.
> +                */
> +               usleep_range(10, 15);
> +       } else {
> +               gpiod_set_value_cansleep(host->device_reset, 0);
> +
> +                /* Some devices may need time to respond to rst_n */
> +               usleep_range(10, 15);
Since sleep the same on assert/de-assert can move it outside the if-else clause? 

> +       }
> 
>         return 0;
>  }

All the below changes, in suspend/resume, deserves some references in your commit log,
And probably a separate patch.

Thanks,
Avri

> @@ -8686,8 +8696,6 @@ static int ufshcd_suspend(struct ufs_hba *hba,
> enum ufs_pm_op pm_op)
>         if (ret)
>                 goto set_dev_active;
> 
> -       ufshcd_vreg_set_lpm(hba);
> -
>  disable_clks:
>         /*
>          * Call vendor specific suspend callback. As these callbacks may access
> @@ -8703,6 +8711,9 @@ static int ufshcd_suspend(struct ufs_hba *hba,
> enum ufs_pm_op pm_op)
>          */
>         ufshcd_disable_irq(hba);
> 
> +       if (ufshcd_is_link_off(hba))
> +               ufshcd_vops_device_reset(hba, true);
> +
>         ufshcd_setup_clocks(hba, false);
> 
>         if (ufshcd_is_clkgating_allowed(hba)) {
> @@ -8711,6 +8722,8 @@ static int ufshcd_suspend(struct ufs_hba *hba,
> enum ufs_pm_op pm_op)
>                                         hba->clk_gating.state);
>         }
> 
> +       ufshcd_vreg_set_lpm(hba);
> +
>         /* Put the host controller in low power mode if possible */
>         ufshcd_hba_vreg_set_lpm(hba);
>         goto out;
> @@ -8778,18 +8791,19 @@ static int ufshcd_resume(struct ufs_hba *hba,
> enum ufs_pm_op pm_op)
>         old_link_state = hba->uic_link_state;
> 
>         ufshcd_hba_vreg_set_hpm(hba);
> +
> +       ret = ufshcd_vreg_set_hpm(hba);
> +       if (ret)
> +               goto out;
> +
>         /* Make sure clocks are enabled before accessing controller */
>         ret = ufshcd_setup_clocks(hba, true);
>         if (ret)
> -               goto out;
> +               goto disable_vreg;
> 
>         /* enable the host irq as host controller would be active soon */
>         ufshcd_enable_irq(hba);
> 
> -       ret = ufshcd_vreg_set_hpm(hba);
> -       if (ret)
> -               goto disable_irq_and_vops_clks;
> -
>         /*
>          * Call vendor specific resume callback. As these callbacks may access
>          * vendor specific host controller register space call them when the
> @@ -8797,7 +8811,7 @@ static int ufshcd_resume(struct ufs_hba *hba,
> enum ufs_pm_op pm_op)
>          */
>         ret = ufshcd_vops_resume(hba, pm_op);
>         if (ret)
> -               goto disable_vreg;
> +               goto disable_irq_and_vops_clks;
> 
>         /* For DeepSleep, the only supported option is to have the link off */
>         WARN_ON(ufshcd_is_ufs_dev_deepsleep(hba) &&
> !ufshcd_is_link_off(hba));
> @@ -8864,8 +8878,6 @@ static int ufshcd_resume(struct ufs_hba *hba,
> enum ufs_pm_op pm_op)
>         ufshcd_link_state_transition(hba, old_link_state, 0);
>  vendor_suspend:
>         ufshcd_vops_suspend(hba, pm_op);
> -disable_vreg:
> -       ufshcd_vreg_set_lpm(hba);
>  disable_irq_and_vops_clks:
>         ufshcd_disable_irq(hba);
>         if (hba->clk_scaling.is_allowed)
> @@ -8876,6 +8888,8 @@ static int ufshcd_resume(struct ufs_hba *hba,
> enum ufs_pm_op pm_op)
>                 trace_ufshcd_clk_gating(dev_name(hba->dev),
>                                         hba->clk_gating.state);
>         }
> +disable_vreg:
> +       ufshcd_vreg_set_lpm(hba);
>  out:
>         hba->pm_op_in_progress = 0;
>         if (ret)
> diff --git a/drivers/scsi/ufs/ufshcd.h b/drivers/scsi/ufs/ufshcd.h
> index 9bb5f0e..d5fbaba 100644
> --- a/drivers/scsi/ufs/ufshcd.h
> +++ b/drivers/scsi/ufs/ufshcd.h
> @@ -319,7 +319,7 @@ struct ufs_pwr_mode_info {
>   * @resume: called during host controller PM callback
>   * @dbg_register_dump: used to dump controller debug information
>   * @phy_initialization: used to initialize phys
> - * @device_reset: called to issue a reset pulse on the UFS device
> + * @device_reset: called to assert or deassert device reset line
>   * @program_key: program or evict an inline encryption key
>   * @event_notify: called to notify important events
>   */
> @@ -350,7 +350,7 @@ struct ufs_hba_variant_ops {
>         int     (*resume)(struct ufs_hba *, enum ufs_pm_op);
>         void    (*dbg_register_dump)(struct ufs_hba *hba);
>         int     (*phy_initialization)(struct ufs_hba *);
> -       int     (*device_reset)(struct ufs_hba *hba);
> +       int     (*device_reset)(struct ufs_hba *hba, bool asserted);
>         void    (*config_scaling_param)(struct ufs_hba *hba,
>                                         struct devfreq_dev_profile *profile,
>                                         void *data);
> @@ -1216,10 +1216,10 @@ static inline void
> ufshcd_vops_dbg_register_dump(struct ufs_hba *hba)
>                 hba->vops->dbg_register_dump(hba);
>  }
> 
> -static inline int ufshcd_vops_device_reset(struct ufs_hba *hba)
> +static inline int ufshcd_vops_device_reset(struct ufs_hba *hba, bool
> asserted)
>  {
>         if (hba->vops && hba->vops->device_reset)
> -               return hba->vops->device_reset(hba);
> +               return hba->vops->device_reset(hba, asserted);
> 
>         return -EOPNOTSUPP;
>  }
> --
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