linux-kernel - Re: [PATCH V4 09/11] scsi: ufs: qcom : Refactor phy_power

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Message-ID: <780d84ca-4004-41ef-a9ae-17532053f8a5@oss.qualcomm.com>
Date: Fri, 9 May 2025 13:35:52 +0200
From: Konrad Dybcio <konrad.dybcio@....qualcomm.com>
To: Nitin Rawat <quic_nitirawa@...cinc.com>, vkoul@...nel.org,
        kishon@...nel.org, manivannan.sadhasivam@...aro.org,
        James.Bottomley@...senPartnership.com, martin.petersen@...cle.com,
        bvanassche@....org, andersson@...nel.org, neil.armstrong@...aro.org
Cc: quic_rdwivedi@...cinc.com, quic_cang@...cinc.com,
        linux-arm-msm@...r.kernel.org, linux-phy@...ts.infradead.org,
        linux-kernel@...r.kernel.org, linux-scsi@...r.kernel.org
Subject: Re: [PATCH V4 09/11] scsi: ufs: qcom : Refactor phy_power_on/off
 calls

On 5/3/25 6:24 PM, Nitin Rawat wrote:
> Commit 3f6d1767b1a0 ("phy: ufs-qcom: Refactor all init steps into
> phy_poweron") removes the phy_power_on/off from ufs_qcom_setup_clocks
> to suspend/resume func.
> 
> To have a better power saving, remove the phy_power_on/off calls from
> resume/suspend path and put them back to ufs_qcom_setup_clocks, so that
> PHY regulators & clks can be turned on/off along with UFS's clocks.
> 
> Since phy phy_power_on is separated out from phy calibrate, make
> separate calls to phy_power_on and phy_calibrate calls from ufs qcom
> driver.
> 
> Co-developed-by: Can Guo <quic_cang@...cinc.com>
> Signed-off-by: Can Guo <quic_cang@...cinc.com>
> Signed-off-by: Nitin Rawat <quic_nitirawa@...cinc.com>
> ---
>  drivers/ufs/host/ufs-qcom.c | 55 ++++++++++++++++---------------------
>  1 file changed, 23 insertions(+), 32 deletions(-)
> 
> diff --git a/drivers/ufs/host/ufs-qcom.c b/drivers/ufs/host/ufs-qcom.c
> index 2cd44ee522b8..ff35cd15c72f 100644
> --- a/drivers/ufs/host/ufs-qcom.c
> +++ b/drivers/ufs/host/ufs-qcom.c
> @@ -639,26 +639,17 @@ static int ufs_qcom_suspend(struct ufs_hba *hba, enum ufs_pm_op pm_op,
>  	enum ufs_notify_change_status status)
>  {
>  	struct ufs_qcom_host *host = ufshcd_get_variant(hba);
> -	struct phy *phy = host->generic_phy;
>  
>  	if (status == PRE_CHANGE)
>  		return 0;
>  
> -	if (ufs_qcom_is_link_off(hba)) {
> -		/*
> -		 * Disable the tx/rx lane symbol clocks before PHY is
> -		 * powered down as the PLL source should be disabled
> -		 * after downstream clocks are disabled.
> -		 */
> +	if (!ufs_qcom_is_link_active(hba))

so is_link_off and !is_link_active are not the same thing - this also allows
for disabling the resources when in hibern8/broken states - is that intended?

>  		ufs_qcom_disable_lane_clks(host);
> -		phy_power_off(phy);
>  
> -		/* reset the connected UFS device during power down */
> -		ufs_qcom_device_reset_ctrl(hba, true);
>  
> -	} else if (!ufs_qcom_is_link_active(hba)) {
> -		ufs_qcom_disable_lane_clks(host);
> -	}
> +	/* reset the connected UFS device during power down */
> +	if (ufs_qcom_is_link_off(hba) && host->device_reset)
> +		ufs_qcom_device_reset_ctrl(hba, true);

similarly this will not be allowed in hibern8/broken states now

>  
>  	return ufs_qcom_ice_suspend(host);
>  }
> @@ -666,26 +657,11 @@ static int ufs_qcom_suspend(struct ufs_hba *hba, enum ufs_pm_op pm_op,
>  static int ufs_qcom_resume(struct ufs_hba *hba, enum ufs_pm_op pm_op)
>  {
>  	struct ufs_qcom_host *host = ufshcd_get_variant(hba);
> -	struct phy *phy = host->generic_phy;
>  	int err;
>  
> -	if (ufs_qcom_is_link_off(hba)) {
> -		err = phy_power_on(phy);
> -		if (err) {
> -			dev_err(hba->dev, "%s: failed PHY power on: %d\n",
> -				__func__, err);
> -			return err;
> -		}
> -
> -		err = ufs_qcom_enable_lane_clks(host);
> -		if (err)
> -			return err;
> -
> -	} else if (!ufs_qcom_is_link_active(hba)) {
> -		err = ufs_qcom_enable_lane_clks(host);
> -		if (err)
> -			return err;
> -	}
> +	err = ufs_qcom_enable_lane_clks(host);
> +	if (err)
> +		return err;
>  
>  	return ufs_qcom_ice_resume(host);
>  }
> @@ -1042,6 +1018,8 @@ static int ufs_qcom_setup_clocks(struct ufs_hba *hba, bool on,
>  				 enum ufs_notify_change_status status)
>  {
>  	struct ufs_qcom_host *host = ufshcd_get_variant(hba);
> +	struct phy *phy = host->generic_phy;
> +	int err;
>  
>  	/*
>  	 * In case ufs_qcom_init() is not yet done, simply ignore.
> @@ -1060,10 +1038,22 @@ static int ufs_qcom_setup_clocks(struct ufs_hba *hba, bool on,
>  				/* disable device ref_clk */
>  				ufs_qcom_dev_ref_clk_ctrl(host, false);
>  			}
> +			err = phy_power_off(phy);

a newline to separate the blocks would improve readability> +			if (err) {
> +				dev_err(hba->dev, "%s: phy power off failed, ret=%d\n",
> +					__func__, err);
> +					return err;

please indent the return statement a tab earlier so it doesn't look
like it's an argument to dev_err()

putting PHY calls in the function that promises to toggle clocks could
also use a comment, maybe extending the kerneldoc to say that certain
clocks come from the PHY so it needs to be managed together

Konrad