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

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Message-ID: <317faeaa-3130-4e28-8c5d-441a76aa79b4@quicinc.com>
Date: Fri, 11 Apr 2025 16:20:33 +0530
From: Nitin Rawat <quic_nitirawa@...cinc.com>
To: Dmitry Baryshkov <dmitry.baryshkov@....qualcomm.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 4/11/2025 1:38 AM, Dmitry Baryshkov wrote:
> 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?

Hi Dmitry,
As part of my patch, I moved the parsing logic from qmp_phy_power_on to 
qmp_ufs_probe to avoid unnecessary parsing during resume. I'm uncertain 
about the circular dependency issue and whether if it still exists.

Regards,
Nitin


> 
>>
>> 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
>>
>