[SRU][PATCH 0/1][X/Z/A] Fix middle button issue of trackpoint

[Aaron Ma]

BugLink: https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1715271

[Impact]
Middle button doesn't work on several Thinkpad laptops like E570, E475, E470, E575 and X1Carbon.

When middle button fails to work, logs show:
psmouse serio2: trackpoint: failed to get extended button data

It fails to read out ext button info via PS2 command.
Almost all the Thinkpad have 3 buttons, so set it to 3 button when it fails to read button info.

[Fix]
Fix it by setting default button info to 3 when failed to detect it.

[Test Case]
Middle button of trackpoint works fine.

[Regression Potential]
Very low.
This patch set the button value to 0x33 after failure of detection.

Oscar Campos (1):
  Input: trackpoint - assume 3 buttons when buttons detection fails

 drivers/input/mouse/trackpoint.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

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2.13.5