linux-kernel - Re: [PATCH] gpio / ACPI: ignore GpioInt() GPIOs when requesting GPIO_OUT

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Date:	Thu, 24 Mar 2016 16:01:33 +0200
From:	Mika Westerberg <mika.westerberg@...ux.intel.com>
To:	Dmitry Torokhov <dmitry.torokhov@...il.com>
Cc:	Linus Walleij <linus.walleij@...aro.org>,
	Alexandre Courbot <gnurou@...il.com>,
	"Rafael J. Wysocki" <rafael.j.wysocki@...el.com>,
	linux-gpio@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] gpio / ACPI: ignore GpioInt() GPIOs when requesting
 GPIO_OUT_*

On Wed, Mar 23, 2016 at 03:58:31PM -0700, Dmitry Torokhov wrote:
> From: Dmitry Torokhov <dtor@...omium.org>
> 
> When firmware does not use _DSD properties that allow properly name GPIO
> resources, the kernel falls back on parsing _CRS resources, and will
> return entries described as GpioInt() as general purpose GPIOs even
> though they are meant to be used simply as interrupt sources for the
> device:
> 
> Device (ETSA)
> {
> 	Name (_HID, "ELAN0001")
> 	...
> 
> 	Method(_CRS, 0x0, NotSerialized)
> 	{
> 		Name(BUF0,ResourceTemplate ()
> 		{
> 			I2CSerialBus(
> 				0x10,                     /* SlaveAddress */
> 				ControllerInitiated,      /* SlaveMode */
> 				400000,                   /* ConnectionSpeed */
> 				AddressingMode7Bit,       /* AddressingMode */
> 				"\\_SB.I2C1",             /* ResourceSource */
> 			)
> 			GpioInt (Edge, ActiveLow, ExclusiveAndWake, PullNone,,
> 				 "\\_SB.GPSW") { BOARD_TOUCH_GPIO_INDEX }
> 		} )
> 		Return (BUF0)
> 	}
> ...
> }
> 
> This gives troubles with drivers such as Elan Touchscreen driver
> (elants_i2c) that uses devm_gpio_get to look up "reset" GPIO line and
> decide whether the driver is responsible for powering up and resetting
> the device or firmware is. In the above case the lookup succeeds, we map
> GPIO as output and later fail to request client->irq interrupt that is
> mapped to the same GPIO.
> 
> Let's ignore resources described as GpioInt() when requesting output
> GPIO (but allow them when requesting GPIOD_ASIS or GPIOD_IN as some
> drivers - i2c-hid - do request GPIO as input and then map it to
> interrupt with gpiod_to_irq).

You could mention here that we only ignore GpioInt() resources in
fallback case.

> BUG=chrome-os-partner:51154
> TEST=Boot Cyan, verify touchscreen work
> 
> Change-Id: Id20c730b937dce8a4135d2b64c8d798372d20e82

This is not needed for mainline patches :)

> Signed-off-by: Dmitry Torokhov <dtor@...omium.org>

Acked-by: Mika Westerberg <mika.westerberg@...ux.intel.com>