[PATCHv2] evdev: handle touchscreens without BTN_TOUCH

[Peter Korsgaard]

Some touchscreens (like the Lumio crystaltouch in single touch mode) send
BTN_LEFT rather than BTN_TOUCH:

Input driver version is 1.0.1
Input device ID: bus 0x3 vendor 0x202e product 0x5 version 0x111
Input device name: "LUMIO Inc LUMIO CrystalTouch ver 1.1C"
Supported events:
  Event type 0 (Sync)
  Event type 1 (Key)
    Event code 272 (LeftBtn)
    Event code 273 (RightBtn)
    Event code 274 (MiddleBtn)
  Event type 2 (Relative)
    Event code 9 (Misc)
  Event type 3 (Absolute)
    Event code 0 (X)
      Value    650
      Min        0
      Max     4095
    Event code 1 (Y)
      Value   3221
      Min        0
      Max     4095
  Event type 4 (Misc)
    Event code 4 (ScanCode)
Testing ... (interrupt to exit)
Event: time 1305882024.934011, type 4 (Misc), code 4 (ScanCode), value 90001
Event: time 1305882024.934017, type 1 (Key), code 272 (LeftBtn), value 1
Event: time 1305882024.934029, type 3 (Absolute), code 0 (X), value 270
Event: time 1305882024.934034, type 3 (Absolute), code 1 (Y), value 1513
Event: time 1305882024.934039, type 2 (Relative), code 9 (Misc), value 1

This causes evdev to handle these device as a mouse rather than a
touchscreen, which naturally doesn't work very well. We already internally
translate BTN_TOUCH as BTN_LEFT, so accept this kind of devices as
touchscreens by checking for devices with BTN_LEFT, absolute X/Y and NO
relative X/Y axes.

Signed-off-by: Peter Korsgaard <jacmet at sunsite.dk>
---
Changes since v1:
- Add as seperate check with explicit checks for no rel X/Y & BTN_LEFT to not 
  interfere with existing logic / not have issues with funky keyboards

 src/evdev.c |    6 ++++++
 1 files changed, 6 insertions(+), 0 deletions(-)

diff --git a/src/evdev.c b/src/evdev.c
index b1a822b..4c05019 100644
--- a/src/evdev.c
+++ b/src/evdev.c
@@ -1692,6 +1692,12 @@ EvdevProbe(InputInfoPtr pInfo)
                     pEvdev->flags |= EVDEV_TOUCHSCREEN;
                     pEvdev->flags |= EVDEV_BUTTON_EVENTS;
                 }
+            } else if (!(TestBit(REL_X, pEvdev->rel_bitmask) &&
+                         TestBit(REL_Y, pEvdev->rel_bitmask)) && has_lmr) {
+                    /* some touchscreens use BTN_LEFT rather than BTN_TOUCH */
+                    xf86IDrvMsg(pInfo, X_PROBED, "Found absolute touchscreen\n");
+                    pEvdev->flags |= EVDEV_TOUCHSCREEN;
+                    pEvdev->flags |= EVDEV_BUTTON_EVENTS;
             }
         }
     }
-- 
1.7.5.1