platform/x86: x86-android-tablets: Fix EBUSY error when requesting IOAPIC IRQs

Sometimes IRQs used by GPIOs in direct-IRQ mode are already registered
because they are used as ACPI "Interrupt () {}" resource for one of the
many bogus I2C devices present in the broken DSDTs of Android x86 tablets.

This is an issue if the existing (bogus) ACPI resource uses different
trigger settings then what is being requested, leading to an -EBUSY
error return of acpi_register_gsi().

Fix this by calling acpi_unregister_gsi() first, so that
the acpi_register_gsi() is allowed to change the trigger settings.

In cases where the GSI has not been registered yet
the acpi_unregister_gsi() is a no-op.
Signed-off-by: Hans de Goede <hdegoede@redhat.com>
Link: https://lore.kernel.org/r/20220223133153.730337-3-hdegoede@redhat.com

drivers/platform/x86/x86-android-tablets.c

@@ -89,6 +89,12 @@ static int x86_acpi_irq_helper_get(const struct x86_acpi_irq_data *data)
 
 	switch (data->type) {
 	case X86_ACPI_IRQ_TYPE_APIC:
+		/*
+		 * The DSDT may already reference the GSI in a device skipped by
+		 * acpi_quirk_skip_i2c_client_enumeration(). Unregister the GSI
+		 * to avoid EBUSY errors in this case.
+		 */
+		acpi_unregister_gsi(data->index);
 		irq = acpi_register_gsi(NULL, data->index, data->trigger, data->polarity);
 		if (irq < 0)
 			pr_err("error %d getting APIC IRQ %d\n", irq, data->index);