Input: wm97xx-core - add retries to wm97xx_read_aux_adc

Add logic to wm97xx_read_aux_adc() to retry reading the adc if the
sample failed.  This could occur if the previous sample was still in
the return register or the sample timed-out.  Also avoid a pathologic
failure mode by disabling the digitizer and returning -EBUSY after 5
retries.

Signed-off-by: Eric Millbrandt <emillbrandt@dekaresearch.com>
Acked-by: Mark Brown <broonie@opensource.wolfsonmicro.com>
Signed-off-by: Dmitry Torokhov <dtor@mail.ru>

1 files changed, 13 insertions, 2 deletions

diff --git a/drivers/input/touchscreen/wm97xx-core.c b/drivers/input/touchscreen/wm97xx-core.c
index 770537c14628..6b75c9f660ae 100644
--- a/drivers/input/touchscreen/wm97xx-core.c
+++ b/drivers/input/touchscreen/wm97xx-core.c
@@ -125,6 +125,8 @@ int wm97xx_read_aux_adc(struct wm97xx *wm, u16 adcsel)
 {
         int power_adc = 0, auxval;
         u16 power = 0;
+        int rc = 0;
+        int timeout = 0;
 
         /* get codec */
         mutex_lock(&wm->codec_mutex);
@@ -143,7 +145,9 @@ int wm97xx_read_aux_adc(struct wm97xx *wm, u16 adcsel)
 
         /* Turn polling mode on to read AUX ADC */
         wm->pen_probably_down = 1;
-        wm->codec->poll_sample(wm, adcsel, &auxval);
+
+        while (rc != RC_VALID && timeout++ < 5)
+                rc = wm->codec->poll_sample(wm, adcsel, &auxval);
 
         if (power_adc)
                 wm97xx_reg_write(wm, AC97_EXTENDED_MID, power | 0x8000);
@@ -152,8 +156,15 @@ int wm97xx_read_aux_adc(struct wm97xx *wm, u16 adcsel)
 
         wm->pen_probably_down = 0;
 
+        if (timeout >= 5) {
+                dev_err(wm->dev,
+                        "timeout reading auxadc %d, disabling digitiser\n",
+                        adcsel);
+                wm->codec->dig_enable(wm, false);
+        }
+
         mutex_unlock(&wm->codec_mutex);
-        return auxval & 0xfff;
+        return (rc == RC_VALID ? auxval & 0xfff : -EBUSY);
 }
 EXPORT_SYMBOL_GPL(wm97xx_read_aux_adc);