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| author | Benjamin Tissoires <benjamin.tissoires@redhat.com> | 2015-03-30 21:54:15 +0300 |
|---|---|---|
| committer | Jiri Kosina <jkosina@suse.cz> | 2015-04-07 16:16:36 +0300 |
| commit | c627589282213bbef12a482c0b87f23526ceb3f0 (patch) | |
| tree | 21f56937f6f819ce9bbc81aafdeeb2ce8a4f7938 /drivers/input | |
| parent | b9e9cd32ba33d13c7ecbc15b9f4418beded403d2 (diff) | |
| download | linux-c627589282213bbef12a482c0b87f23526ceb3f0.tar.xz | |
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/input')
| -rw-r--r-- | drivers/input/input-mt.c | 9 |
1 files changed, 7 insertions, 2 deletions
diff --git a/drivers/input/input-mt.c b/drivers/input/input-mt.c index fbe29fcb15c5..f4b58f77c524 100644 --- a/drivers/input/input-mt.c +++ b/drivers/input/input-mt.c @@ -88,10 +88,13 @@ int input_mt_init_slots(struct input_dev *dev, unsigned int num_slots, goto err_mem; } - /* Mark slots as 'unused' */ + /* Mark slots as 'inactive' */ for (i = 0; i < num_slots; i++) input_mt_set_value(&mt->slots[i], ABS_MT_TRACKING_ID, -1); + /* Mark slots as 'unused' */ + mt->frame = 1; + dev->mt = mt; return 0; err_mem: @@ -430,6 +433,8 @@ EXPORT_SYMBOL(input_mt_assign_slots); * set the key on the first unused slot and return. * * If no available slot can be found, -1 is returned. + * Note that for this function to work properly, input_mt_sync_frame() has + * to be called at each frame. */ int input_mt_get_slot_by_key(struct input_dev *dev, int key) { @@ -444,7 +449,7 @@ int input_mt_get_slot_by_key(struct input_dev *dev, int key) return s - mt->slots; for (s = mt->slots; s != mt->slots + mt->num_slots; s++) - if (!input_mt_is_active(s)) { + if (!input_mt_is_active(s) && !input_mt_is_used(mt, s)) { s->key = key; return s - mt->slots; } |