Wait a little bit longer, 50mS instead of 20mS, until the driver starts polling for pen-up. The problematic behavior before this patch is applied is as follows. The behavior was observed on the STMPE610QTR controller. Upon a physical pen-down event, the touchscreen reports one set of x-y-p coordinates and a pen-down event. After that, the pen-up polling is triggered and since the controller is not ready yet, the polling mistakenly detects a pen-up event while the physical state is still such that the pen is down on the touch surface. The pen-up handling flushes the controller FIFO, so after that, all the samples in the controller are discarded. The controller becomes ready shortly after this bogus pen-up handling and does generate again a pen-down interrupt. This time, the controller contains x-y-p samples which all read as zero. Since pressure value is zero, this set of samples is effectively ignored by userland. In the end, the driver just bounces between pen-down and bogus pen-up handling, generating no useful results. Fix this by giving the controller a bit more time before polling it for pen-up. Signed-off-by: Marek Vasut <marex@xxxxxxx> Cc: Vipul Kumar Samar <vipulkumar.samar@xxxxxx> Cc: Viresh Kumar <viresh.kumar@xxxxxxxxxx> Cc: Dmitry Torokhov <dmitry.torokhov@xxxxxxxxx> --- drivers/input/touchscreen/stmpe-ts.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/drivers/input/touchscreen/stmpe-ts.c b/drivers/input/touchscreen/stmpe-ts.c index 9e5c880..a8f5ea7 100644 --- a/drivers/input/touchscreen/stmpe-ts.c +++ b/drivers/input/touchscreen/stmpe-ts.c @@ -164,7 +164,7 @@ static irqreturn_t stmpe_ts_handler(int irq, void *data) STMPE_TSC_CTRL_TSC_EN, STMPE_TSC_CTRL_TSC_EN); /* start polling for touch_det to detect release */ - schedule_delayed_work(&ts->work, msecs_to_jiffies(20)); + schedule_delayed_work(&ts->work, msecs_to_jiffies(50)); return IRQ_HANDLED; } -- 2.1.4 -- 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
