Re: [PATCH v3 4/4] scsi: ufs-mediatek: gate ref-clk during Auto-Hibern8

[Alim Akhtar]

Hello Stanley

On Wed, Jan 29, 2020 at 1:10 PM Stanley Chu <stanley.chu@xxxxxxxxxxxx> wrote:
>
> In current UFS driver design, hba->uic_link_state will not
> be changed after link enters Hibern8 state by Auto-Hibern8 mechanism.
> In this case, reference clock gating will be skipped unless special
> handling is implemented in vendor's callbacks.
>
> Support reference clock gating during Auto-Hibern8 period in
> MediaTek Chipsets: If link state is already in Hibern8 while
> Auto-Hibern8 feature is enabled, gate reference clock in
> setup_clocks callback.
>
> Signed-off-by: Stanley Chu <stanley.chu@xxxxxxxxxxxx>

Reviewed-by: Alim Akhtar <alim.akhtar@xxxxxxxxxxx>
> ---
>  drivers/scsi/ufs/ufs-mediatek.c | 38 +++++++++++++++++++++++----------
>  drivers/scsi/ufs/ufs-mediatek.h | 12 +++++++++++
>  2 files changed, 39 insertions(+), 11 deletions(-)
>
> diff --git a/drivers/scsi/ufs/ufs-mediatek.c b/drivers/scsi/ufs/ufs-mediatek.c
> index d78897a14905..0ce08872d671 100644
> --- a/drivers/scsi/ufs/ufs-mediatek.c
> +++ b/drivers/scsi/ufs/ufs-mediatek.c
> @@ -143,6 +143,17 @@ static int ufs_mtk_setup_ref_clk(struct ufs_hba *hba, bool on)
>         return 0;
>  }
>
> +static u32 ufs_mtk_link_get_state(struct ufs_hba *hba)
> +{
> +       u32 val;
> +
> +       ufshcd_writel(hba, 0x20, REG_UFS_DEBUG_SEL);
> +       val = ufshcd_readl(hba, REG_UFS_PROBE);
> +       val = val >> 28;
> +
> +       return val;
> +}
> +
>  /**
>   * ufs_mtk_setup_clocks - enables/disable clocks
>   * @hba: host controller instance
> @@ -155,7 +166,7 @@ static int ufs_mtk_setup_clocks(struct ufs_hba *hba, bool on,
>                                 enum ufs_notify_change_status status)
>  {
>         struct ufs_mtk_host *host = ufshcd_get_variant(hba);
> -       int ret = -EINVAL;
> +       int ret = 0;
>
>         /*
>          * In case ufs_mtk_init() is not yet done, simply ignore.
> @@ -165,19 +176,24 @@ static int ufs_mtk_setup_clocks(struct ufs_hba *hba, bool on,
>         if (!host)
>                 return 0;
>
> -       switch (status) {
> -       case PRE_CHANGE:
> -               if (!on && !ufshcd_is_link_active(hba)) {
> +       if (!on && status == PRE_CHANGE) {
> +               if (!ufshcd_is_link_active(hba)) {
>                         ufs_mtk_setup_ref_clk(hba, on);
>                         ret = phy_power_off(host->mphy);
> +               } else {
> +                       /*
> +                        * Gate ref-clk if link state is in Hibern8
> +                        * triggered by Auto-Hibern8.
> +                        */
> +                       if (!ufshcd_can_hibern8_during_gating(hba) &&
> +                           ufshcd_is_auto_hibern8_enabled(hba) &&
> +                           ufs_mtk_link_get_state(hba) ==
> +                           VS_LINK_HIBERN8)
> +                               ufs_mtk_setup_ref_clk(hba, on);
>                 }
> -               break;
> -       case POST_CHANGE:
> -               if (on) {
> -                       ret = phy_power_on(host->mphy);
> -                       ufs_mtk_setup_ref_clk(hba, on);
> -               }
> -               break;
> +       } else if (on && status == POST_CHANGE) {
> +               ret = phy_power_on(host->mphy);
> +               ufs_mtk_setup_ref_clk(hba, on);
>         }
>
>         return ret;
> diff --git a/drivers/scsi/ufs/ufs-mediatek.h b/drivers/scsi/ufs/ufs-mediatek.h
> index fccdd979d6fb..492414e5f481 100644
> --- a/drivers/scsi/ufs/ufs-mediatek.h
> +++ b/drivers/scsi/ufs/ufs-mediatek.h
> @@ -53,6 +53,18 @@
>  #define VS_SAVEPOWERCONTROL         0xD0A6
>  #define VS_UNIPROPOWERDOWNCONTROL   0xD0A8
>
> +/*
> + * Vendor specific link state
> + */
> +enum {
> +       VS_LINK_DISABLED            = 0,
> +       VS_LINK_DOWN                = 1,
> +       VS_LINK_UP                  = 2,
> +       VS_LINK_HIBERN8             = 3,
> +       VS_LINK_LOST                = 4,
> +       VS_LINK_CFG                 = 5,
> +};
> +
>  /*
>   * SiP commands
>   */
> --
> 2.18.0



-- 
Regards,
Alim