[ACPI] re-enable platform-specific hotkey drivers by default

When both platform-specific and generic drivers exist,
enable generic over-ride with "acpi_generic_hotkey".

http://bugzilla.kernel.org/show_bug.cgi?id=4953Signed-off-by: Luming Yu <luming.yu@intel.com>
Signed-off-by: Len Brown <len.brown@intel.com>

Documentation/acpi-hotkey.txt

@@ -33,3 +33,6 @@ The result of the execution of this aml method is
 attached to /proc/acpi/hotkey/poll_method, which is dnyamically
 created.  Please use command "cat /proc/acpi/hotkey/polling_method" 
 to retrieve it.
+
+Note: Use cmdline "acpi_generic_hotkey" to over-ride
+loading any platform specific drivers.

Documentation/kernel-parameters.txt

@@ -159,6 +159,11 @@ running once the system is up.
 
 	acpi_fake_ecdt	[HW,ACPI] Workaround failure due to BIOS lacking ECDT
 
+	acpi_generic_hotkey [HW,ACPI]
+			Allow consolidated generic hotkey driver to
+			over-ride platform specific driver.
+			See also Documentation/acpi-hotkey.txt.
+
 	ad1816=		[HW,OSS]
 			Format: <io>,<irq>,<dma>,<dma2>
 			See also Documentation/sound/oss/AD1816.

drivers/acpi/osl.c

@@ -71,7 +71,7 @@ EXPORT_SYMBOL(acpi_in_debugger);
 extern char line_buf[80];
 #endif /*ENABLE_DEBUGGER*/
 
-int acpi_specific_hotkey_enabled;
+int acpi_specific_hotkey_enabled = TRUE;
 EXPORT_SYMBOL(acpi_specific_hotkey_enabled);
 
 static unsigned int acpi_irq_irq;
@@ -1158,11 +1158,11 @@ __setup("acpi_wake_gpes_always_on", acpi_wake_gpes_always_on_setup);
 int __init
 acpi_hotkey_setup(char *str)
 {
-	acpi_specific_hotkey_enabled = TRUE;
+	acpi_specific_hotkey_enabled = FALSE;
 	return 1;
 }
 
-__setup("acpi_specific_hotkey", acpi_hotkey_setup);
+__setup("acpi_generic_hotkey", acpi_hotkey_setup);
 
 /*
  * max_cstate is defined in the base kernel so modules can