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>

1 files changed, 6 insertions, 2 deletions

diff --git a/drivers/input/touchscreen/wm9712.c b/drivers/input/touchscreen/wm9712.c
index a983da1744e8..3b4eed4b8690 100644
--- 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;