linux-kernel - Re: [PATCH] gpiolib: return -ENOENT when no GPIO mapping exists

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Date:	Tue, 10 Dec 2013 12:11:56 +0900
From:	Alex Courbot <acourbot@...dia.com>
To:	Mika Westerberg <mika.westerberg@...ux.intel.com>
CC:	Linus Walleij <linus.walleij@...aro.org>,
	Andy Shevchenko <andriy.shevchenko@...ux.intel.com>,
	"linux-gpio@...r.kernel.org" <linux-gpio@...r.kernel.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] gpiolib: return -ENOENT when no GPIO mapping exists

On 12/09/2013 09:40 PM, Mika Westerberg wrote:
> On Fri, Dec 06, 2013 at 11:06:56AM +0900, Alexandre Courbot wrote:
>> Some devices drivers make use of optional GPIO parameters. For such
>> drivers, it is important to discriminate between the case where no
>> GPIO mapping has been defined for the function they are requesting, and
>> the case where a mapping exists but an error occured while resolving it
>> or when acquiring the GPIO.
>>
>> This patch changes the family of gpiod_get() functions such that they
>> will return -ENOENT if and only if no GPIO mapping is defined for the
>> requested function. Other error codes are used when an actual error
>> occured during the GPIO resolution.
>>
>> Signed-off-by: Alexandre Courbot <acourbot@...dia.com>
>> ---
>> I think this change should be merged early as not having it may prevent
>> some users to switch to gpiod. I stumbled upon this issue while
>> considering porting a simple driver (pwm_bl) that has an optional GPIO
>> parameter.
>>
>> Mika, Andy: if Linus agrees with this change, could you take care of
>> having -ENOENT returned as well for the ACPI and SFI GPIOs lookup?
>
> Sure. I have a patch for this already so once this gets merged, I'll send
> out the ACPI version.

Please feel free to send it now, as it should not break anything if your 
patch is merged before mine anyway.

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