linux-kernel - Re: [PATCH V1] pinctrl: qcom: spmi-gpio: Update GPIO EN

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Date:   Tue, 10 Oct 2017 08:17:52 +0800
From:   Fenglin Wu <fenglinw@...eaurora.org>
To:     Bjorn Andersson <bjorn.andersson@...aro.org>
Cc:     linux-arm-msm@...r.kernel.org, linux-kernel@...r.kernel.org,
        Linus Walleij <linus.walleij@...aro.org>,
        linux-gpio@...r.kernel.org, collinsd@...eaurora.org,
        aghayal@...eaurora.org, wruan@...eaurora.org,
        subbaram@...eaurora.org, kgunda@...eaurora.org
Subject: Re: [PATCH V1] pinctrl: qcom: spmi-gpio: Update GPIO EN_CTL when
 setting pin config

On 10/9/2017 1:56 PM, Bjorn Andersson wrote:
> On Sun 08 Oct 22:34 PDT 2017, Fenglin Wu wrote:
> 
>> On 10/6/2017 12:27 AM, Bjorn Andersson wrote:
>>> On Mon 11 Sep 17:32 PDT 2017, fenglinw@...eaurora.org wrote:
>>>
>>>> From: Fenglin Wu <fenglinw@...eaurora.org>
>>>>
>>>> GPIO is expected to be disabled iff PIN_CONFIG_BIAS_HIGH_IMPEDANCE is
>>>> configured. Update is_enabled flag in config_set() so that it can
>>>> reflect GPIO status correctly. Also modify EN_CTL register based on
>>>> is_enabled flag in config_set() to configure the GPIO properly.
>>>>
>>>> Signed-off-by: Fenglin Wu <fenglinw@...eaurora.org>
>>>> ---
>>>>    drivers/pinctrl/qcom/pinctrl-spmi-gpio.c | 5 +++++
>>>>    1 file changed, 5 insertions(+)
>>>>
>>>> diff --git a/drivers/pinctrl/qcom/pinctrl-spmi-gpio.c b/drivers/pinctrl/qcom/pinctrl-spmi-gpio.c
>>>> index c2c0bab..a0edaa8 100644
>>>> --- a/drivers/pinctrl/qcom/pinctrl-spmi-gpio.c
>>>> +++ b/drivers/pinctrl/qcom/pinctrl-spmi-gpio.c
>>>> @@ -453,6 +453,7 @@ static int pmic_gpio_config_set(struct pinctrl_dev *pctldev, unsigned int pin,
>>>>    	pad = pctldev->desc->pins[pin].drv_data;
>>>> +	pad->is_enabled = true;
>>>>    	for (i = 0; i < nconfs; i++) {
>>>>    		param = pinconf_to_config_param(configs[i]);
>>>>    		arg = pinconf_to_config_argument(configs[i]);
>>>> @@ -600,6 +601,10 @@ static int pmic_gpio_config_set(struct pinctrl_dev *pctldev, unsigned int pin,
>>>>    			return ret;
>>>>    	}
>>>> +	val = pad->is_enabled << PMIC_GPIO_REG_MASTER_EN_SHIFT;
>>>> +
>>>> +	ret = pmic_gpio_write(state, pad, PMIC_GPIO_REG_EN_CTL, val);
>>>> +
>>>
>>> This looks good.
>>>
>>> Acked-by: Bjorn Andersson <bjorn.andersson@...aro.org>
>>>
>>>
>>> But I spotted another issue while reviewing this; currently the initial
>>> state of is_enabled is unconditionally set to enabled in
>>> pmic_gpio_populate(), so reading the initial pinconf or configuring a
>>> pinmux before setting a pinconf will operate on the potentially wrong
>>> information.
>>>
>>> So I think the initial value should be read out from REG_EN_CTL rather
>>> than being just "true".
>>>
>>> Can you please either submit another patch for this?
>>
>> Hmm, considering a GPIO which is disabled by default in hardware
>> setting, what's its expected state if we only define "function" for it?
>> I was thinking we need to enable it once it has any setting in pinmux or
>> pinconf. If you think that we need to keep its original state until we
>> set pinconf for it, yes, I can submit a change to address this.
>>
> 
> Are there valid cases where only function should be selected and no
> other configuration is used? If so it makes sense to make
> pmic_gpio_set_mux() enable the block.
> 
> 
> Regardless of this, if there are disabled pins that are not mentioned in
> DT they will still appear as enabled in the debugfs interface; and this
> I consider an error worth fixing.
How about we do both: read the HW initial state in pmic_gpio_populate(),
and also enable the GPIO block in pmic_gpio_set_mux()?

> 
> Regards,
> Bjorn
> 

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