ACPI: thinkpad-acpi: checkpoint sysfs interface version due to hotkey

The change in the size of the hotkey mask, the hability to report the keys
that use the higher bits, and the addition of the hotkey_radio_sw attribute
are important enough features to warrant increasing the minor field of the
sysfs interface version.

Also, document a bit better how and when the thinkpad-acpi sysfs interface
version will be updated.

Signed-off-by: Henrique de Moraes Holschuh <hmh@hmh.eng.br>
Signed-off-by: Len Brown <len.brown@intel.com>

1 files changed, 17 insertions, 0 deletions

diff --git a/Documentation/thinkpad-acpi.txt b/Documentation/thinkpad-acpi.txt
index fe26e50a2b15..7a06a27ee37b 100644
--- a/Documentation/thinkpad-acpi.txt
+++ b/Documentation/thinkpad-acpi.txt
@@ -134,6 +134,21 @@ end of this document.  Changes to the sysfs interface done by the kernel
 subsystems are not documented here, nor are they tracked by this
 attribute.
 
+Changes to the thinkpad-acpi sysfs interface are only considered
+non-experimental when they are submitted to Linux mainline, at which
+point the changes in this interface are documented and interface_version
+may be updated.  If you are using any thinkpad-acpi features not yet
+sent to mainline for merging, you do so on your own risk: these features
+may disappear, or be implemented in a different and incompatible way by
+the time they are merged in Linux mainline.
+
+Changes that are backwards-compatible by nature (e.g. the addition of
+attributes that do not change the way the other attributes work) do not
+always warrant an update of interface_version.  Therefore, one must
+expect that an attribute might not be there, and deal with it properly
+(an attribute not being there *is* a valid way to make it clear that a
+feature is not available in sysfs).
+
 Hot keys
 --------
 
@@ -989,3 +1004,5 @@ Sysfs interface changelog:
 
 0x000100:	Initial sysfs support, as a single platform driver and
 		device.
+0x000200:	Hot key support for 32 hot keys, and radio slider switch
+		support.