ACPICA: Misc comments to minimize code divergence

Modify/add some comments to minimize ACPICA/linux GPE code divergence.

Acked-by: Rafael J. Wysocki <rjw@sisk.pl>
Signed-off-by: Lin Ming <ming.m.lin@intel.com>
Signed-off-by: Len Brown <len.brown@intel.com>
diff --git a/drivers/acpi/acpica/hwgpe.c b/drivers/acpi/acpica/hwgpe.c
index 7c6d485..85c3cbd 100644
--- a/drivers/acpi/acpica/hwgpe.c
+++ b/drivers/acpi/acpica/hwgpe.c
@@ -62,10 +62,10 @@
  * PARAMETERS:	gpe_event_info	    - Info block for the GPE
  *		gpe_register_info   - Info block for the GPE register
  *
- * RETURN:	Status
+ * RETURN:	Register mask with a one in the GPE bit position
  *
- * DESCRIPTION:	Compute GPE enable mask with one bit corresponding to the given
- *		GPE set.
+ * DESCRIPTION: Compute the register mask for this GPE. One bit is set in the
+ *              correct position for the input GPE.
  *
  ******************************************************************************/
 
@@ -85,12 +85,12 @@
  *
  * RETURN:	Status
  *
- * DESCRIPTION: Enable or disable a single GPE in its enable register.
+ * DESCRIPTION: Enable or disable a single GPE in the parent enable register.
  *
  ******************************************************************************/
 
 acpi_status
-acpi_hw_low_set_gpe(struct acpi_gpe_event_info *gpe_event_info, u8 action)
+acpi_hw_low_set_gpe(struct acpi_gpe_event_info *gpe_event_info, u32 action)
 {
 	struct acpi_gpe_register_info *gpe_register_info;
 	acpi_status status;
@@ -113,14 +113,20 @@
 		return (status);
 	}
 
-	/* Set ot clear just the bit that corresponds to this GPE */
+	/* Set or clear just the bit that corresponds to this GPE */
 
 	register_bit = acpi_hw_get_gpe_register_bit(gpe_event_info,
 						gpe_register_info);
 	switch (action) {
 	case ACPI_GPE_CONDITIONAL_ENABLE:
-		if (!(register_bit & gpe_register_info->enable_for_run))
+
+		/* Only enable if the enable_for_run bit is set */
+
+		if (!(register_bit & gpe_register_info->enable_for_run)) {
 			return (AE_BAD_PARAMETER);
+		}
+
+		/*lint -fallthrough */
 
 	case ACPI_GPE_ENABLE:
 		ACPI_SET_BIT(enable_mask, register_bit);
@@ -131,7 +137,7 @@
 		break;
 
 	default:
-		ACPI_ERROR((AE_INFO, "Invalid action\n"));
+		ACPI_ERROR((AE_INFO, "Invalid GPE Action, %u\n", action));
 		return (AE_BAD_PARAMETER);
 	}
 
@@ -168,13 +174,13 @@
 		return (AE_NOT_EXIST);
 	}
 
-	register_bit = acpi_hw_get_gpe_register_bit(gpe_event_info,
-						gpe_register_info);
-
 	/*
 	 * Write a one to the appropriate bit in the status register to
 	 * clear this GPE.
 	 */
+	register_bit =
+	    acpi_hw_get_gpe_register_bit(gpe_event_info, gpe_register_info);
+
 	status = acpi_hw_write(register_bit,
 			       &gpe_register_info->status_address);
 
@@ -201,8 +207,8 @@
 	u32 in_byte;
 	u32 register_bit;
 	struct acpi_gpe_register_info *gpe_register_info;
-	acpi_status status;
 	acpi_event_status local_event_status = 0;
+	acpi_status status;
 
 	ACPI_FUNCTION_ENTRY();