linux-kernel - Re: Hidden dependency of i2c-hid on GPIOLIB

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Message-ID: <7007524.JGeOHMMZVW@xps13>
Date:	Tue, 14 Apr 2015 12:03:51 +0200
From:	Gabriele Mazzotta <gabriele.mzt@...il.com>
To:	Mika Westerberg <mika.westerberg@...ux.intel.com>
Cc:	Jiri Kosina <jkosina@...e.cz>, linux-input@...r.kernel.org,
	linux-kernel@...r.kernel.org,
	Benjamin Tissoires <benjamin.tissoires@...hat.com>
Subject: Re: Hidden dependency of i2c-hid on GPIOLIB

On Tuesday 14 April 2015 12:59:24 Mika Westerberg wrote:
> On Tue, Apr 14, 2015 at 12:55:20AM +0200, Gabriele Mazzotta wrote:
> > Hi,
> > 
> > my touchpad stopped working because of a485923efbb8 ("HID: i2c-hid:
> > Add support for ACPI GPIO interrupts"). It turned out that I need
> > CONFIG_GPIOLIB. I think this dependency should be made explicit or the
> > driver should not depend on it.
> 
> Using GPIOs should be optional. Gpiolib stubs functions out whenever it
> is not enabled.
> 
> However, I made a mistake when GPIOs are fed to the driver. If gpiolib
> is not enabled acpi_dev_add_driver_gpios() returns -ENXIO and prevents
> your touchpad from working.
> 
> I think it is alright to ignore the error here. Can you try if below
> patch helps?

Sorry for not being more specific. Yes, the problem is that
acpi_dev_add_driver_gpios() returns -ENXIO if CONFIG_GPIOLIB is not set.

> diff --git a/drivers/hid/i2c-hid/i2c-hid.c b/drivers/hid/i2c-hid/i2c-hid.c
> index ab4dd952b6ba..b427c11d4cd3 100644
> --- a/drivers/hid/i2c-hid/i2c-hid.c
> +++ b/drivers/hid/i2c-hid/i2c-hid.c
> @@ -877,7 +877,8 @@ static int i2c_hid_acpi_pdata(struct i2c_client *client,
>  	pdata->hid_descriptor_address = obj->integer.value;
>  	ACPI_FREE(obj);
>  
> -	return acpi_dev_add_driver_gpios(adev, i2c_hid_acpi_gpios);
> +	acpi_dev_add_driver_gpios(adev, i2c_hid_acpi_gpios);
> +	return 0;
>  }
>  
>  static const struct acpi_device_id i2c_hid_acpi_match[] = {
--
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