Input: wm9712 - fix wrong pen up readings

Often a reading can be wrong. This patch assures that this is really a
pen up event and not a false reading.

Based on wm9712: pen up by Teresa Gámez and Christian Hemp.

Signed-off-by: Markus Pargmann <mpa@pengutronix.de>
Acked-by: Mark Brown <broonie@opensource.wolfsonmicro.com>
Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>

diff --git a/drivers/input/touchscreen/wm9712.c b/drivers/input/touchscreen/wm9712.c
index a983da1..3b4eed4 100644 (file)
--- a/drivers/input/touchscreen/wm9712.c
+++ b/drivers/input/touchscreen/wm9712.c
@@ -302,8 +302,12 @@ static int wm9712_poll_sample(struct wm97xx *wm, int adcsel, int *sample)
        }
 
        if (wants_pen && !(*sample & WM97XX_PEN_DOWN)) {
-               wm->pen_probably_down = 0;
-               return RC_PENUP;
+               /* Sometimes it reads a wrong value the first time. */
+               *sample = wm97xx_reg_read(wm, AC97_WM97XX_DIGITISER_RD);
+               if (!(*sample & WM97XX_PEN_DOWN)) {
+                       wm->pen_probably_down = 0;
+                       return RC_PENUP;
+               }
        }
 
        return RC_VALID;