[PATCH]: ACPI Cleanup :Initialize EC global lock based on the return status

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Subject: ACPI: Cleanup :Initialize EC global lock based on the return status
From: Zhao Yakui <yakui.zhao@xxxxxxxxx>

Initialize the EC global lock based on the returned value of _GLK object.
Only when AE_OK is returned by the acpi_evaluate_integer, the EC global lock
will be assigned based on the return value of _GLK object.Otherwise it means
that there is no _GLK object and the global lock won't be required when EC
is accessed.
If the return value of _GLK object is not zero, it means that GLobal lock
will be required when EC is accessed.
If the return value of _GLK object is zero, it means that GLobal lock
won't be required when EC is accessed.

Signed-off-by: Zhao Yakui <yakui.zhao@xxxxxxxxx>
cc: Alexey Starikovskiy <astarikovskiy@xxxxxxx>
cc: Alan Jenkins <alan-jenkins@xxxxxxxxxxxxxx>

---
 drivers/acpi/ec.c |   24 ++++++++++++++++++++++--
 1 file changed, 22 insertions(+), 2 deletions(-)

Index: linux-2.6/drivers/acpi/ec.c
===================================================================
--- linux-2.6.orig/drivers/acpi/ec.c
+++ linux-2.6/drivers/acpi/ec.c
@@ -752,8 +752,28 @@ ec_parse_device(acpi_handle handle, u32 
 	ec->gpe = tmp;
 	/* Use the global lock for all EC transactions? */
 	tmp = 0;
-	acpi_evaluate_integer(handle, "_GLK", NULL, &tmp);
-	ec->global_lock = tmp;
+	/*
+	 * Only when AE_OK is returned by acpi_evaluate_interger,
+	 * the ec->global_lock will be assigned based on the returned
+	 * value by _GLK. Otherwise it means that there is no _GLK object
+	 * and global lock won't be required when EC is accessed.
+	 * If the return value of _GLK object is not zero, it means that
+	 * global lock will be required when EC is accessed.
+	 * If the return value of _GLK object is zero, it means that
+	 * global lock won't be required when EC is accessed.
+	 */
+	status = acpi_evaluate_integer(handle, "_GLK", NULL, &tmp);
+	if (ACPI_SUCCESS(status)) {
+		/*
+		 * If the return value is not zero, it means that global lock
+		 * is required when EC is accessed
+		 */
+		if (tmp)
+			ec->global_lock = 1;
+		else
+			ec->global_lock = 0;
+	} else
+		ec->global_lock = 0;
 	ec->handle = handle;
 	return AE_CTRL_TERMINATE;
 }


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