linux-kernel - Re: [PATCH] ACPI: Add GPIO-signaled event emulator.

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Message-ID: <1828087.V5efjsXTdI@vostro.rjw.lan>
Date:	Tue, 26 Aug 2014 00:39:59 +0200
From:	"Rafael J. Wysocki" <rjw@...ysocki.net>
To:	Tomasz Nowicki <tomasz.nowicki@...aro.org>
Cc:	Mika Westerberg <mika.westerberg@...ux.intel.com>,
	linus.walleij@...aro.org, gnurou@...il.com,
	linux-acpi@...r.kernel.org, linux-kernel@...r.kernel.org,
	linaro-acpi@...ts.linaro.org
Subject: Re: [PATCH] ACPI: Add GPIO-signaled event emulator.

On Thursday, August 21, 2014 04:39:46 PM Tomasz Nowicki wrote:
> Hi Mika,
> 
> On 21.08.2014 12:45, Mika Westerberg wrote:
> > On Wed, Aug 20, 2014 at 04:58:20PM +0200, Tomasz Nowicki wrote:

[cut]

> >> +
> >> +static int gpio_evt_trigger(void *data, u64 val)
> >> +{
> >> +	struct gpio_pin_data *pin_data = (struct gpio_pin_data *)data;
> >> +	int pin = pin_data->pin;
> >> +
> >> +	if (ACPI_FAILURE(acpi_execute_simple_method(pin_data->handle, NULL,
> >> +						    pin <= 255 ? 0 : pin)))
> >> +		pr_err(PREFIX "evaluating event method failed\n");
> >
> > acpi_execute_simple_method() passes one argument to the method. You
> > can't use it with _Lxx or _Exx which don't expect any arguments.
> > Otherwise you get this:
> >
> > [  122.258191] ACPI: \_SB_.GPO2._E12: Excess arguments - Caller passed 1, method requires 0 (20140724/nsarguments-263)
> Right, I will fix it.

OK, so here's my concern.

If AML does any kind of tracking of state in _Exx/_Lxx, you'll likely totally
confuse it by calling those things at random.

I'm not sure I'm seeing a compelling reason to put this thing into the tree
for this reason.

Rafael

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