linux-kernel - Re: [PATCH v8 4/5] scsi: ufs: Power on phy after it is initialized

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Date:   Thu, 9 Aug 2018 11:00:37 -0700
From:   Evan Green <evgreen@...omium.org>
To:     cang@...eaurora.org
Cc:     subhashj@...eaurora.org, asutoshd@...eaurora.org,
        vivek.gautam@...eaurora.org, Manu Gautam <mgautam@...eaurora.org>,
        kishon@...com, robh+dt@...nel.org, mark.rutland@....com,
        linux-kernel@...r.kernel.org, devicetree@...r.kernel.org,
        linux-arm-msm@...r.kernel.org
Subject: Re: [PATCH v8 4/5] scsi: ufs: Power on phy after it is initialized

On Tue, Jul 31, 2018 at 3:09 AM Can Guo <cang@...eaurora.org> wrote:
>
> Before UFS PHY is initialized, powering on it has no effect but increases
> the PHY's power on count. Then when power on PHY to enable it after phy
> initialization where it is really needed, as PHY's power on count is not
> zero, again it would do nothing but directly return and leaves the PHY
> disabled. This change adds condition checks to phy power on calls which
> happen before phy initialization.
>
> Signed-off-by: Can Guo <cang@...eaurora.org>
> ---
>  drivers/scsi/ufs/ufs-qcom.c | 4 +++-
>  drivers/scsi/ufs/ufs-qcom.h | 1 +
>  2 files changed, 4 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/scsi/ufs/ufs-qcom.c b/drivers/scsi/ufs/ufs-qcom.c
> index 2b38db2..4e9d526 100644
> --- a/drivers/scsi/ufs/ufs-qcom.c
> +++ b/drivers/scsi/ufs/ufs-qcom.c
> @@ -288,6 +288,7 @@ static int ufs_qcom_power_up_sequence(struct ufs_hba *hba)
>                         __func__, ret);
>                 goto out;
>         }
> +       host->is_phy_init = true;
>
>         /* De-assert PHY reset and start serdes */
>         ufs_qcom_deassert_reset(hba);
> @@ -1147,7 +1148,8 @@ static int ufs_qcom_setup_clocks(struct ufs_hba *hba, bool on,
>                 return 0;
>
>         if (on && (status == POST_CHANGE)) {
> -               phy_power_on(host->generic_phy);
> +               if (host->is_phy_init)
> +                       phy_power_on(host->generic_phy);
>
>                 /* enable the device ref clock for HS mode*/
>                 if (ufshcd_is_hs_mode(&hba->pwr_info))
> diff --git a/drivers/scsi/ufs/ufs-qcom.h b/drivers/scsi/ufs/ufs-qcom.h
> index 295f4be..5747aa3 100644
> --- a/drivers/scsi/ufs/ufs-qcom.h
> +++ b/drivers/scsi/ufs/ufs-qcom.h
> @@ -242,6 +242,7 @@ struct ufs_qcom_host {
>         /* Bitmask for enabling debug prints */
>         u32 dbg_print_en;
>         struct ufs_qcom_testbus testbus;
> +       bool is_phy_init;
>  };
>
>  static inline u32
> --
> The Qualcomm Innovation Center, Inc. is a member of the Code Aurora Forum,
> a Linux Foundation Collaborative Project
>
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Reviewed-by: Evan Green <evgreen@...omium.org>