linux-kernel - Re: [PATCH V3 4/9] phy: qcom-qmp-ufs: Refactor UFS PHY reset

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Message-ID: <pur4y63xhfmqlyymg4pehk37ry4gg22h24zceoqjbsxp3hj4yf@4kptase3c4qp>
Date: Thu, 10 Apr 2025 23:08:24 +0300
From: Dmitry Baryshkov <dmitry.baryshkov@....qualcomm.com>
To: Nitin Rawat <quic_nitirawa@...cinc.com>
Cc: vkoul@...nel.org, kishon@...nel.org, manivannan.sadhasivam@...aro.org,
        James.Bottomley@...senpartnership.com, martin.petersen@...cle.com,
        bvanassche@....org, bjorande@...cinc.com, neil.armstrong@...aro.org,
        konrad.dybcio@....qualcomm.com, quic_rdwivedi@...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 V3 4/9] phy: qcom-qmp-ufs: Refactor UFS PHY reset

On Thu, Apr 10, 2025 at 02:30:57PM +0530, Nitin Rawat wrote:
> Refactor the UFS PHY reset handling to parse the reset logic only once
> during probe, instead of every resume.
> 
> Move the UFS PHY reset parsing logic from qmp_phy_power_on to
> qmp_ufs_probe to avoid unnecessary parsing during resume.

How did you solve the circular dependency issue being noted below?

> 
> Co-developed-by: Ram Kumar Dwivedi <quic_rdwivedi@...cinc.com>
> Signed-off-by: Ram Kumar Dwivedi <quic_rdwivedi@...cinc.com>
> Signed-off-by: Nitin Rawat <quic_nitirawa@...cinc.com>
> ---
>  drivers/phy/qualcomm/phy-qcom-qmp-ufs.c | 61 +++++++++++++------------
>  1 file changed, 33 insertions(+), 28 deletions(-)
> 
> diff --git a/drivers/phy/qualcomm/phy-qcom-qmp-ufs.c b/drivers/phy/qualcomm/phy-qcom-qmp-ufs.c
> index 636dc3dc3ea8..12dad28cc1bd 100644
> --- a/drivers/phy/qualcomm/phy-qcom-qmp-ufs.c
> +++ b/drivers/phy/qualcomm/phy-qcom-qmp-ufs.c
> @@ -1799,38 +1799,11 @@ static int qmp_ufs_com_exit(struct qmp_ufs *qmp)
>  static int qmp_ufs_power_on(struct phy *phy)
>  {
>  	struct qmp_ufs *qmp = phy_get_drvdata(phy);
> -	const struct qmp_phy_cfg *cfg = qmp->cfg;
>  	int ret;
>  	dev_vdbg(qmp->dev, "Initializing QMP phy\n");
> 
> -	if (cfg->no_pcs_sw_reset) {
> -		/*
> -		 * Get UFS reset, which is delayed until now to avoid a
> -		 * circular dependency where UFS needs its PHY, but the PHY
> -		 * needs this UFS reset.
> -		 */
> -		if (!qmp->ufs_reset) {
> -			qmp->ufs_reset =
> -				devm_reset_control_get_exclusive(qmp->dev,
> -								 "ufsphy");
> -
> -			if (IS_ERR(qmp->ufs_reset)) {
> -				ret = PTR_ERR(qmp->ufs_reset);
> -				dev_err(qmp->dev,
> -					"failed to get UFS reset: %d\n",
> -					ret);
> -
> -				qmp->ufs_reset = NULL;
> -				return ret;
> -			}
> -		}
> -	}
> -
>  	ret = qmp_ufs_com_init(qmp);
> -	if (ret)
> -		return ret;
> -
> -	return 0;
> +	return ret;
>  }
> 
>  static int qmp_ufs_phy_calibrate(struct phy *phy)
> @@ -2088,6 +2061,34 @@ static int qmp_ufs_parse_dt(struct qmp_ufs *qmp)
>  	return 0;
>  }
> 
> +static int qmp_ufs_get_phy_reset(struct qmp_ufs *qmp)
> +{
> +	const struct qmp_phy_cfg *cfg = qmp->cfg;
> +	int ret;
> +
> +	if (!cfg->no_pcs_sw_reset)
> +		return 0;
> +
> +	/*
> +	 * Get UFS reset, which is delayed until now to avoid a
> +	 * circular dependency where UFS needs its PHY, but the PHY
> +	 * needs this UFS reset.
> +	 */
> +	if (!qmp->ufs_reset) {
> +		qmp->ufs_reset =
> +		devm_reset_control_get_exclusive(qmp->dev, "ufsphy");

Strange indentation.

> +
> +		if (IS_ERR(qmp->ufs_reset)) {
> +			ret = PTR_ERR(qmp->ufs_reset);
> +			dev_err(qmp->dev, "failed to get PHY reset: %d\n", ret);
> +			qmp->ufs_reset = NULL;
> +			return ret;
> +		}
> +	}
> +
> +	return 0;
> +}
> +
>  static int qmp_ufs_probe(struct platform_device *pdev)
>  {
>  	struct device *dev = &pdev->dev;
> @@ -2114,6 +2115,10 @@ static int qmp_ufs_probe(struct platform_device *pdev)
>  	if (ret)
>  		return ret;
> 
> +	ret = qmp_ufs_get_phy_reset(qmp);
> +	if (ret)
> +		return ret;
> +
>  	/* Check for legacy binding with child node. */
>  	np = of_get_next_available_child(dev->of_node, NULL);
>  	if (np) {
> --
> 2.48.1
> 

-- 
With best wishes
Dmitry