gpiolib: acpi: Do not set the IRQ type if the IRQ is already in use

If the IRQ is already in use, then acpi_dev_gpio_irq_get_by() really
should not change the type underneath the current owner.

I specifically hit an issue with this an a Chuwi Hi8 Super (CWI509) Bay
Trail tablet, when the Boot OS selection in the BIOS is set to Android.
In this case _STA for a MAX17047 ACPI I2C device wrongly returns 0xf and
the _CRS resources for this device include a GpioInt pointing to a GPIO
already in use by an _AEI handler, with a different type then specified
in the _CRS for the MAX17047 device. Leading to the acpi_dev_gpio_irq_get()
call done by the i2c-core-acpi.c code changing the type breaking the
_AEI handler.

Now this clearly is a bug in the DSDT of this tablet (in Android mode),
but in general calling irq_set_irq_type() on an IRQ which already is
in use seems like a bad idea.

Signed-off-by: Hans de Goede <hdegoede@redhat.com>
Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>

diff --git a/drivers/gpio/gpiolib-acpi.c b/drivers/gpio/gpiolib-acpi.c
index 7dd0484..02b06e6 100644 (file)
--- a/drivers/gpio/gpiolib-acpi.c
+++ b/drivers/gpio/gpiolib-acpi.c
@@ -1044,10 +1044,17 @@ int acpi_dev_gpio_irq_get_by(struct acpi_device *adev, const char *name, int ind
                        irq_flags = acpi_dev_get_irq_type(info.triggering,
                                                          info.polarity);
 
-                       /* Set type if specified and different than the current one */
-                       if (irq_flags != IRQ_TYPE_NONE &&
-                           irq_flags != irq_get_trigger_type(irq))
-                               irq_set_irq_type(irq, irq_flags);
+                       /*
+                        * If the IRQ is not already in use then set type
+                        * if specified and different than the current one.
+                        */
+                       if (can_request_irq(irq, irq_flags)) {
+                               if (irq_flags != IRQ_TYPE_NONE &&
+                                   irq_flags != irq_get_trigger_type(irq))
+                                       irq_set_irq_type(irq, irq_flags);
+                       } else {
+                               dev_dbg(&adev->dev, "IRQ %d already in use\n", irq);
+                       }
 
                        return irq;
                }