The synaptics touchpad on the Acer Aspire One D250 will report y coordinate values in excess of 8000 near the bottom of the touchpad, well outside of the range of values that the synaptics documentation says should be reported. In addition, the y values abruptly change from very low values to these very high values. After the calculation to invert the y coordinates, userspace gets y coordinates that can jump suddenly between large positive and moderately large negative values, causing sudden jumps in the pointer position. To work around this odd behavior, reject any coordinates with values outside of absolute limits specified by Synaptics, which is 6143 for both axes. BugLink: http://bugs.launchpad.net/bugs/1001251 Cc: stable@xxxxxxxxxxxxxxx Signed-off-by: Seth Forshee <seth.forshee@xxxxxxxxxxxxx> --- I'm not sure whether the limits here should be the hard-coded value or the coordinates reported by the device when that's supported (i.e. whether the coordinates reported by the device are always within the range of 0 to 6143). If the latter is more appropriate I can modify the patch to use the device-reported values and fall back to the hard-coded values. drivers/input/mouse/synaptics.c | 5 +++++ 1 file changed, 5 insertions(+) diff --git a/drivers/input/mouse/synaptics.c b/drivers/input/mouse/synaptics.c index e07eb9b..f62299d 100644 --- a/drivers/input/mouse/synaptics.c +++ b/drivers/input/mouse/synaptics.c @@ -40,6 +40,8 @@ * Note that newer firmware allows querying device for maximum useable * coordinates. */ +#define XMAX 6143 +#define YMAX 6143 #define XMIN_NOMINAL 1472 #define XMAX_NOMINAL 5472 #define YMIN_NOMINAL 1408 @@ -555,6 +557,9 @@ static int synaptics_parse_hw_state(const unsigned char buf[], hw->right = (buf[0] & 0x02) ? 1 : 0; } + if (hw->x > XMAX || hw->y > YMAX) + return 1; + return 0; } -- 1.7.9.5 -- To unsubscribe from this list: send the line "unsubscribe linux-input" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
