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

[Nitin Rawat <quic_nitirawa@quicinc.com>]

On 4/11/2025 4:38 PM, Dmitry Baryshkov wrote:
> On Fri, 11 Apr 2025 at 13:50, Nitin Rawat <quic_nitirawa@quicinc.com> wrote:
>>
>>
>>
>> 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.
> 
> It surely does. The reset controller is registered in the beginning of
> ufs_qcom_init() and the PHY is acquired only a few lines below. It
> creates a very small window for PHY driver to probe.
> Which means, NAK, this patch doesn't look acceptable.

Hi Dmitry,

Thanks for pointing this out. I agree that it leaves very little time 
for the PHY to probe, which may cause issues with targets where 
no_pcs_sw_reset is set to true.

As an experiment, I kept no_pcs_sw_reset set to true for the SM8750, and 
it caused bootup probe issues in some of the iterations I ran.

To address this, I propose updating the patch to move the 
qmp_ufs_get_phy_reset call to phy_calibrate, just before the 
reset_control_assert call.

This change will delay the UFS PHY reset as much as possible in the 
code. Additionally, moving it from phy_power_on to calibrate will ensure 
that qmp_ufs_get_phy_reset is called only once during boot, rather than 
during each phy_power_on call.

Please let me know your thoughts.
=====================================================================================================
  static int qmp_ufs_phy_calibrate(struct phy *phy)
  {
         struct qmp_ufs *qmp = phy_get_drvdata(phy);
@@ -1793,6 +1826,12 @@ static int qmp_ufs_phy_calibrate(struct phy *phy)
         unsigned int val;
         int ret;

+       pr_err("%s %d\n", __func__, __LINE__);
+
+       ret = qmp_ufs_get_phy_reset(qmp);
+        if (ret)
+                return ret;
+
         ret = reset_control_assert(qmp->ufs_reset);
         if (ret)
                 return ret;
@@ -1817,7 +1856,7 @@ static int qmp_ufs_phy_calibrate(struct phy *phy)
                 dev_err(qmp->dev, "phy initialization timed-out\n");
                 return ret;
=====================================================================================================


Regards.
Nitin
> 
>>
>> Regards,
>> Nitin
>>
>>
>>>
>>>>
>>>> Co-developed-by: Ram Kumar Dwivedi <quic_rdwivedi@quicinc.com>
>>>> Signed-off-by: Ram Kumar Dwivedi <quic_rdwivedi@quicinc.com>
>>>> Signed-off-by: Nitin Rawat <quic_nitirawa@quicinc.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
>>>>
>>>
>>
> 
> 


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