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| author | Benjamin Tissoires <benjamin.tissoires@redhat.com> | 2015-03-30 14:54:15 -0400 |
|---|---|---|
| committer | Jiri Kosina <jkosina@suse.cz> | 2015-04-07 15:16:36 +0200 |
| commit | c627589282213bbef12a482c0b87f23526ceb3f0 (patch) | |
| tree | 21f56937f6f819ce9bbc81aafdeeb2ce8a4f7938 /drivers/hid/hid-debug.c | |
| parent | b9e9cd32ba33d13c7ecbc15b9f4418beded403d2 (diff) | |
| download | lwn-c627589282213bbef12a482c0b87f23526ceb3f0.tar.gz lwn-c627589282213bbef12a482c0b87f23526ceb3f0.zip | |
Input - mt: Fix input_mt_get_slot_by_key
The case occurred recently with a touchscreen using twice a slot during a
single EV_SYN event:
E: 0.288415 0000 0000 0000 # ------------ SYN_REPORT (0) ----------
E: 0.296207 0003 002f 0000 # EV_ABS / ABS_MT_SLOT 0
E: 0.296207 0003 0039 -001 # EV_ABS / ABS_MT_TRACKING_ID -1
E: 0.296207 0003 002f 0001 # EV_ABS / ABS_MT_SLOT 1
E: 0.296207 0003 0035 0908 # EV_ABS / ABS_MT_POSITION_X 908
E: 0.296207 0003 0036 1062 # EV_ABS / ABS_MT_POSITION_Y 1062
E: 0.296207 0003 002f 0000 # EV_ABS / ABS_MT_SLOT 0
E: 0.296207 0003 0039 8787 # EV_ABS / ABS_MT_TRACKING_ID 8787
E: 0.296207 0003 0035 1566 # EV_ABS / ABS_MT_POSITION_X 1566
E: 0.296207 0003 0036 0861 # EV_ABS / ABS_MT_POSITION_Y 861
E: 0.296207 0003 0000 0908 # EV_ABS / ABS_X 908
E: 0.296207 0003 0001 1062 # EV_ABS / ABS_Y 1062
E: 0.296207 0000 0000 0000 # ------------ SYN_REPORT (0) ----------
This occurred because while having already slots 0 and 1 assigned, the
touchscreen sent:
0.293377 Tip Switch: 0 | Contact Id: 0 | X: 539 | Y: 1960 | Contact Count: 3
0.294783 Tip Switch: 1 | Contact Id: 1 | X: 908 | Y: 1062 | Contact Count: 0
0.296187 Tip Switch: 1 | Contact Id: 2 | X: 1566 | Y: 861 | Contact Count: 0
Slot 0 is released correclty, but when we look for Contact ID 2, the slot
0 is then picked up again because it is marked as inactive (trackingID < 0).
This is wrong, and we should not reuse a slot in the same frame.
The test should also check for input_mt_is_used().
In addition, we need to initialize mt->frame to an other value than 0.
With mt->frame being 0, all slots are tags as currently used, and so
input_mt_get_slot_by_key() would return -1 for all requests.
Fixes: https://bugs.freedesktop.org/show_bug.cgi?id=88903
Signed-off-by: Benjamin Tissoires <benjamin.tissoires@redhat.com>
Acked-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>
Diffstat (limited to 'drivers/hid/hid-debug.c')
0 files changed, 0 insertions, 0 deletions