ACPI: Use GPE reference counting to support shared GPEs

[linux-beck.git] / drivers / acpi / ec.c

diff --git a/drivers/acpi/ec.c b/drivers/acpi/ec.c
index 0fa65a8210daa99d63fd6f61eeb885af8d8f8033..27e0b92b2e39c01a1c7cb1e8e9dd305c1bf613b0 100644 (file)
--- a/drivers/acpi/ec.c
+++ b/drivers/acpi/ec.c
@@ -307,6 +307,10 @@ static int acpi_ec_transaction(struct acpi_ec *ec, struct transaction *t)
        pr_debug(PREFIX "transaction start\n");
        /* disable GPE during transaction if storm is detected */
        if (test_bit(EC_FLAGS_GPE_STORM, &ec->flags)) {
+               /*
+                * It has to be disabled at the hardware level regardless of the
+                * GPE reference counting, so that it doesn't trigger.
+                */
                acpi_set_gpe(NULL, ec->gpe, ACPI_GPE_DISABLE);
        }
 
@@ -316,7 +320,11 @@ static int acpi_ec_transaction(struct acpi_ec *ec, struct transaction *t)
        ec_check_sci_sync(ec, acpi_ec_read_status(ec));
        if (test_bit(EC_FLAGS_GPE_STORM, &ec->flags)) {
                msleep(1);
-               /* it is safe to enable GPE outside of transaction */
+               /*
+                * It is safe to enable the GPE outside of the transaction.  Use
+                * acpi_set_gpe() for that, since we used it to disable the GPE
+                * above.
+                */
                acpi_set_gpe(NULL, ec->gpe, ACPI_GPE_ENABLE);
        } else if (t->irq_count > ACPI_EC_STORM_THRESHOLD) {
                pr_info(PREFIX "GPE storm detected, "
@@ -1059,7 +1067,7 @@ error:
 static int acpi_ec_suspend(struct acpi_device *device, pm_message_t state)
 {
        struct acpi_ec *ec = acpi_driver_data(device);
-       /* Stop using GPE */
+       /* Stop using the GPE, but keep it reference counted. */
        acpi_set_gpe(NULL, ec->gpe, ACPI_GPE_DISABLE);
        return 0;
 }
@@ -1067,7 +1075,7 @@ static int acpi_ec_suspend(struct acpi_device *device, pm_message_t state)
 static int acpi_ec_resume(struct acpi_device *device)
 {
        struct acpi_ec *ec = acpi_driver_data(device);
-       /* Enable use of GPE back */
+       /* Enable the GPE again, but don't reference count it once more. */
        acpi_set_gpe(NULL, ec->gpe, ACPI_GPE_ENABLE);
        return 0;
 }