linux-kernel - Re: [PATCH 4/4] mfd: twl6040-core: Use gpio_request

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Message-ID: <4ED7446B.5000806@compulab.co.il>
Date:	Thu, 01 Dec 2011 11:10:03 +0200
From:	Igor Grinberg <grinberg@...pulab.co.il>
To:	axel.lin@...il.com
CC:	linux-kernel@...r.kernel.org,
	Misael Lopez Cruz <misael.lopez@...com>,
	Jorge Eduardo Candelaria <jorge.candelaria@...com>,
	Samuel Ortiz <sameo@...ux.intel.com>
Subject: Re: [PATCH 4/4] mfd: twl6040-core: Use gpio_request_one

On 12/01/11 10:18, Axel Lin wrote:
> 2011/12/1 Igor Grinberg <grinberg@...pulab.co.il>:
>> On 12/01/11 03:55, Axel Lin wrote:
>>> Use gpio_request_one() instead of multiple gpiolib calls.
>>>
>>> Signed-off-by: Axel Lin <axel.lin@...il.com>
>>> ---
>>>  drivers/mfd/twl6040-core.c |    7 ++-----
>>>  1 files changed, 2 insertions(+), 5 deletions(-)
>>>
>>> diff --git a/drivers/mfd/twl6040-core.c b/drivers/mfd/twl6040-core.c
>>> index 268f80f..e57b1d1 100644
>>> --- a/drivers/mfd/twl6040-core.c
>>> +++ b/drivers/mfd/twl6040-core.c
>>> @@ -509,13 +509,10 @@ static int __devinit twl6040_probe(struct platform_device *pdev)
>>>               twl6040->audpwron = -EINVAL;
>>>
>>>       if (gpio_is_valid(twl6040->audpwron)) {
>>> -             ret = gpio_request(twl6040->audpwron, "audpwron");
>>> +             ret = gpio_request_one(twl6040->audpwron, GPIOF_OUT_INIT_LOW,
>>> +                                    "audpwron");
>>>               if (ret)
>>>                       goto gpio1_err;
>>> -
>>> -             ret = gpio_direction_output(twl6040->audpwron, 0);
>>> -             if (ret)
>>> -                     goto gpio2_err;
>>>       }
>>
>> same here, double check gpio_is_valid()?
> 
> In the case of
> twl6040->audpwron = -EINVAL;  ( see line 509 )
> gpio_is_valid returns false, we just don't request gpio.
> 
> If we remove the gpio_is_valid checking here,
> then gpio_request_one will return -EINVAL.
> Then the code always goes to the error path if twl6040->audpwron is -EINVAL.

Thanks for the explanation.
So the GPIO is optional - now it makes sense to me.


-- 
Regards,
Igor.
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