[PATCH v2] Input: wm97xx-core - add retries to wm97xx_read_aux_adc

[Eric Millbrandt <emillbrandt@dekaresearch.com>]

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>
---

changes since v1
- fix minor style issue, checkpatch.pl now reports no warnings

 drivers/input/touchscreen/wm97xx-core.c |   11 +++++++++--
 1 files changed, 9 insertions(+), 2 deletions(-)

diff --git a/drivers/input/touchscreen/wm97xx-core.c b/drivers/input/touchscreen/wm97xx-core.c
index cbfef1e..2419507 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 +156,11 @@ int wm97xx_read_aux_adc(struct wm97xx *wm, u16 adcsel)

        wm->pen_probably_down = 0;

+       if (timeout >= 5)
+               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);

--
1.6.3.1

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