[PATCH v3] Input: wm97xx-core - add retries to wm97xx_read_aux_adc

[PATCH v3] Input: wm97xx-core - add retries to wm97xx_read_aux_adc

[Eric Millbrandt]

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

changes since v2
- add error message if the adc read timed out

 drivers/input/touchscreen/wm97xx-core.c |   15 +++++++++++++--
 1 files changed, 13 insertions(+), 2 deletions(-)

diff --git a/drivers/input/touchscreen/wm97xx-core.c b/drivers/input/touchscreen/wm97xx-core.c
index cbfef1e..035f089 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);

--
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Re: [PATCH v3] Input: wm97xx-core - add retries to wm97xx_read_aux_adc

[Mark Brown]

On Fri, Sep 03, 2010 at 09:13:34AM -0400, Eric Millbrandt wrote:
> 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>

Good stuff - thanks!

Acked-by: Mark Brown <broonie@opensource.wolfsonmicro.com>

Re: [PATCH v3] Input: wm97xx-core - add retries to wm97xx_read_aux_adc

[Dmitry Torokhov]

On Fri, Sep 03, 2010 at 02:25:09PM +0100, Mark Brown wrote:
> On Fri, Sep 03, 2010 at 09:13:34AM -0400, Eric Millbrandt wrote:
> > 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>
> 
> Good stuff - thanks!
> 
> Acked-by: Mark Brown <broonie@opensource.wolfsonmicro.com>

Applied to next, thanks.

-- 
Dmitry