linux-kernel - Re: [PATCH V10 4/9] mfd: pm8008: Add reset-gpios

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Message-ID: <104b529b-946d-f171-5a82-6052aef2dbbb@quicinc.com>
Date:   Wed, 27 Apr 2022 11:33:08 +0530
From:   "Satya Priya Kakitapalli (Temp)" <quic_c_skakit@...cinc.com>
To:     Stephen Boyd <swboyd@...omium.org>
CC:     <linux-arm-msm@...r.kernel.org>, <devicetree@...r.kernel.org>,
        <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH V10 4/9] mfd: pm8008: Add reset-gpios


On 4/27/2022 10:58 AM, Satya Priya Kakitapalli (Temp) wrote:
>
> On 4/18/2022 10:34 AM, Satya Priya Kakitapalli (Temp) wrote:
>>
>> On 4/15/2022 5:40 AM, Stephen Boyd wrote:
>>> Quoting Satya Priya (2022-04-14 05:30:13)
>>>> diff --git a/drivers/mfd/qcom-pm8008.c b/drivers/mfd/qcom-pm8008.c
>>>> index c472d7f..97a72da 100644
>>>> --- a/drivers/mfd/qcom-pm8008.c
>>>> +++ b/drivers/mfd/qcom-pm8008.c
>>>> @@ -239,6 +241,13 @@ static int pm8008_probe(struct i2c_client 
>>>> *client)
>>>>                          dev_err(chip->dev, "Failed to probe irq 
>>>> periphs: %d\n", rc);
>>>>          }
>>>>
>>>> +       chip->reset_gpio = devm_gpiod_get(chip->dev, "reset", 
>>>> GPIOD_OUT_HIGH);
>>>> +       if (IS_ERR(chip->reset_gpio)) {
>>>> +               dev_err(chip->dev, "failed to acquire reset gpio\n");
>>> The API looks to print debug messages. This print doesn't look 
>>> required.
>>
>>
>> Okay.
>>
>>
>>>> +               return PTR_ERR(chip->reset_gpio);
>>>> +       }
>>>> +       gpiod_set_value(chip->reset_gpio, 1);
>>> Does this do anything? Does this work just as well?
>>>
>>>     reset_gpio = devm_gpiod_get(chip->dev, "reset", GPIOD_OUT_LOW);
>>>     if (IS_ERR(reset_gpio))
>>>         return PTR_ERR(reset_gpio);
>>>
>
> This is not working as expected. We need to add 
> "gpiod_set_value(chip->reset_gpio, 1);"  to actually toggle the line.
>

I checked again and it is working after using GPIOD_OUT_HIGH instead of LOW.

reset_gpio = devm_gpiod_get(chip->dev, "reset", GPIOD_OUT_HIGH);
     if (IS_ERR(reset_gpio))
         return PTR_ERR(reset_gpio);


>
>>> Note that there's no point to store the reset gpio in the structure if
>>> it won't be used outside of probe.
>>
>>
>> Okay, I'll use a local variable.
>>
>>
>>> This should work fine? I used
>>> GPIOD_OUT_LOW to indicate that the reset should be returned to this
>>> function deasserted, i.e. taking the PMIC out of reset.
>>
>>
>> I'll try this out.
>>
>>