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

Nitin Rawat
2025-04-16T09:09:03Z

On 4/15/2025 2:59 PM, Dmitry Baryshkov wrote:
> On 14/04/2025 23:34, Nitin Rawat wrote:
>>
>>
>> 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.
>
> Will it cause an issue if we move it to phy_init() instead of
> phy_calibrate()?

Hi Dmitry,

Thanks for suggestion.
Phy_init is invoked before phy_set_mode_ext and ufs_qcom_phy_power_on,
whereas calibrate is called after ufs_qcom_phy_power_on. Keeping the UFS
PHY reset in phy_calibrate introduces relatively more delay, providing
more buffer time for the PHY driver probe, ensuring the UFS PHY reset is
handled correctly the first time.

Moving the calibration to phy_init shouldn't cause any issues. However,
since we currently don't have an initialization operations registered
for init, we would need to add a new PHY initialization ops if we decide
to move it to phy_init.

Please let me know if this looks fine to you, or if you have any
suggestions. I am open to your suggestions.

Regards,
Nitin

>
>>
>> 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
>>>>>>
>>>>>
>>>>
>>>
>>>
>>
>
>