tree c6263696a1beb4b03edd0bfe076bf1190b18a99c
parent 8253d42be8ae8c81cabcf678448c09a69d4f3b8c
author Jason Gerecke <killertofu@gmail.com> 1446598678 -0800
committer Jiri Kosina <jkosina@suse.cz> 1446719515 +0100

HID: wacom: Call 'wacom_query_tablet_data' only after 'hid_hw_start'

When connecting the Cintiq Companion 2 as an external tablet (i.e., using
it in "hybrid" mode) it has been seen to cause the kernel of the machine
it is connected to to Oops. The cause has been traced to us attempting to
switch the tablet's mode prior to actually starting HID device (resulting
in the eventual dereference of the uninitialized control URB).

Commit 3b164a0 moved the mode switch from occuring post-start to occurring
pre-start. The change was not seen to cause issues largely due to the fact
that most devices mode switch with 'hid_hw_raw_request' (which is safe to
call prior to start) rather than 'hid_hw_request'.

Moving the call back to its original location resolves the issue, but
causes some touch-only Bamboo tablets (e.g. 056a:00d0) to stop working.
The affected tablets require us to perform a mode switch on their
vestigial pen interface prior ignoring with -ENODEV, meaning that the
code which is responsible for doing the ignoring has to move as well.

Signed-off-by: Jason Gerecke <jason.gerecke@wacom.com>
Reviewed-by: Ping Cheng <pingc@wacom.com>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>