linux-kernel - Re: [PATCH v2] usb: typec: qcom: check regulator enable status before disabling it

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Message-ID: <9574a219-3abf-b2c9-7d90-e79d364134bb@linaro.org>
Date:   Thu, 24 Aug 2023 15:37:22 +0100
From:   Bryan O'Donoghue <bryan.odonoghue@...aro.org>
To:     Heikki Krogerus <heikki.krogerus@...ux.intel.com>,
        quic_huliu@...cinc.com
Cc:     Guenter Roeck <linux@...ck-us.net>, Andy Gross <agross@...nel.org>,
        Bjorn Andersson <andersson@...nel.org>,
        Konrad Dybcio <konrad.dybcio@...aro.org>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        linux-arm-msm@...r.kernel.org, linux-usb@...r.kernel.org,
        linux-kernel@...r.kernel.org, quic_fenglinw@...cinc.com,
        subbaram@...cinc.com
Subject: Re: [PATCH v2] usb: typec: qcom: check regulator enable status before
 disabling it

On 24/08/2023 15:12, Heikki Krogerus wrote:
> On Thu, Aug 24, 2023 at 10:32:03AM +0800, Hui Liu via B4 Relay wrote:
>> From: Hui Liu <quic_huliu@...cinc.com>
>>
>> Check regulator enable status before disabling it to avoid
>> unbalanced regulator disable warnings.
>>
>> Reviewed-by: Guenter Roeck <linux@...ck-us.net>
>> Fixes: a4422ff22142 ("usb: typec: qcom: Add Qualcomm PMIC Type-C driver")
>> Reviewed-by: Bryan O'Donoghue <bryan.odonoghue@...aro.org>
>> Signed-off-by: Hui Liu <quic_huliu@...cinc.com>
>> ---
>> Changes in v2:
>> - Add Fixes tag
>> - Link to v1: https://lore.kernel.org/r/20230823-qcom-tcpc-v1-1-fa81a09ca056@quicinc.com
>> ---
>>   drivers/usb/typec/tcpm/qcom/qcom_pmic_typec_pdphy.c | 3 ++-
>>   1 file changed, 2 insertions(+), 1 deletion(-)
>>
>> diff --git a/drivers/usb/typec/tcpm/qcom/qcom_pmic_typec_pdphy.c b/drivers/usb/typec/tcpm/qcom/qcom_pmic_typec_pdphy.c
>> index bb0b8479d80f..ca616b17b5b6 100644
>> --- a/drivers/usb/typec/tcpm/qcom/qcom_pmic_typec_pdphy.c
>> +++ b/drivers/usb/typec/tcpm/qcom/qcom_pmic_typec_pdphy.c
>> @@ -422,7 +422,8 @@ static int qcom_pmic_typec_pdphy_disable(struct pmic_typec_pdphy *pmic_typec_pdp
>>   	ret = regmap_write(pmic_typec_pdphy->regmap,
>>   			   pmic_typec_pdphy->base + USB_PDPHY_EN_CONTROL_REG, 0);
>>   
>> -	regulator_disable(pmic_typec_pdphy->vdd_pdphy);
>> +	if (regulator_is_enabled(pmic_typec_pdphy->vdd_pdphy))
>> +		regulator_disable(pmic_typec_pdphy->vdd_pdphy);
> 
> Would it be an option to just enable the regulator in
> qcom_pmic_typec_pdphy_start() and disable it in
> qcom_pmic_typec_pdphy_stop()?
> 
> Now the whole thing looks weird. That regulator is in practice
> only disabled and then enabled in one and the same place -
> pmic_typec_pdphy_reset(). It's not touched anywhere else. That makes
> the above condition confusing to me. I may be missing something.
> 
> At least more explanation is needed.
> 
> thanks,
> 

I don't see why not.

The code would look neater that way too.

Can you give it a try Hui ?

diff --git a/drivers/usb/typec/tcpm/qcom/qcom_pmic_typec_pdphy.c 
b/drivers/usb/typec/tcpm/qcom/qcom_pmic_typec_pdphy.c
index 4e1b846627d20..d29f9506e5f12 100644
--- a/drivers/usb/typec/tcpm/qcom/qcom_pmic_typec_pdphy.c
+++ b/drivers/usb/typec/tcpm/qcom/qcom_pmic_typec_pdphy.c
@@ -383,10 +383,6 @@ static int qcom_pmic_typec_pdphy_enable(struct 
pmic_typec_pdphy *pmic_typec_pdph
         struct device *dev = pmic_typec_pdphy->dev;
         int ret;

-       ret = regulator_enable(pmic_typec_pdphy->vdd_pdphy);
-       if (ret)
-               return ret;
-
         /* PD 2.0, DR=TYPEC_DEVICE, PR=TYPEC_SINK */
         ret = regmap_update_bits(pmic_typec_pdphy->regmap,
                                  pmic_typec_pdphy->base + 
USB_PDPHY_MSG_CONFIG_REG,
@@ -424,8 +420,6 @@ static int qcom_pmic_typec_pdphy_disable(struct 
pmic_typec_pdphy *pmic_typec_pdp
         ret = regmap_write(pmic_typec_pdphy->regmap,
                            pmic_typec_pdphy->base + 
USB_PDPHY_EN_CONTROL_REG, 0);

-       regulator_disable(pmic_typec_pdphy->vdd_pdphy);
-
         return ret;
  }

@@ -449,6 +443,10 @@ int qcom_pmic_typec_pdphy_start(struct 
pmic_typec_pdphy *pmic_typec_pdphy,
         int i;
         int ret;

+       ret = regulator_enable(pmic_typec_pdphy->vdd_pdphy);
+       if (ret)
+               return ret;
+
         pmic_typec_pdphy->tcpm_port = tcpm_port;

         ret = pmic_typec_pdphy_reset(pmic_typec_pdphy);
@@ -469,6 +467,8 @@ void qcom_pmic_typec_pdphy_stop(struct 
pmic_typec_pdphy *pmic_typec_pdphy)
                 disable_irq(pmic_typec_pdphy->irq_data[i].irq);

         qcom_pmic_typec_pdphy_reset_on(pmic_typec_pdphy);
+
+       regulator_disable(pmic_typec_pdphy->vdd_pdphy);
  }

---
bod