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

From: Tomasz Nowicki
Date: Thu Aug 28 2014 - 07:19:54 EST

On 26.08.2014 00:39, Rafael J. Wysocki wrote:
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:


+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.

Yes you are right, but this emulator is only for debugging/development purposes and goes with clear statement "DANGER to use on production kernel", like APEI error injection feature.

IMO, this emulator would help with:
1. testing and developing AML methods
2. working on ACPI subsystems that need GPIO-signaled events without GPIO h/w

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