Re: [PATCH] iio/adc: ingenic: Fix AUX/VBAT readings when touchscreen is used

From: Jonathan Cameron
Date: Sun Nov 08 2020 - 10:37:22 EST


On Wed, 04 Nov 2020 23:25:12 +0100
Artur Rojek <contact@xxxxxxxxxxxxxx> wrote:

> Hi Paul,
>
> On 2020-11-03 21:12, Paul Cercueil wrote:
> > When the command feature of the ADC is used, it is possible to program
> > the ADC, and specify at each step what input should be processed, and
> > in
> > comparison to what reference.
> >
> > This broke the AUX and battery readings when the touchscreen was
> > enabled, most likely because the CMD feature would change the VREF all
> > the time.
> >
> > Now, when AUX or battery are read, we temporarily disable the CMD
> > feature, which means that we won't get touchscreen readings in that
> > time
> > frame. But it now gives correct values for AUX / battery, and the
> > touchscreen isn't disabled for long enough to be an actual issue.
> >
> > Fixes: b96952f498db ("IIO: Ingenic JZ47xx: Add touchscreen mode.")
> > Cc: <stable@xxxxxxxxxxxxxxx>
> > Signed-off-by: Paul Cercueil <paul@xxxxxxxxxxxxxxx>
> > ---
> > drivers/iio/adc/ingenic-adc.c | 33 +++++++++++++++++++++++++++------
> > 1 file changed, 27 insertions(+), 6 deletions(-)
> >
> > diff --git a/drivers/iio/adc/ingenic-adc.c
> > b/drivers/iio/adc/ingenic-adc.c
> > index 92b25083e23f..ecaff6a9b716 100644
> > --- a/drivers/iio/adc/ingenic-adc.c
> > +++ b/drivers/iio/adc/ingenic-adc.c
> > @@ -177,13 +177,12 @@ static void ingenic_adc_set_config(struct
> > ingenic_adc *adc,
> > mutex_unlock(&adc->lock);
> > }
> >
> > -static void ingenic_adc_enable(struct ingenic_adc *adc,
> > - int engine,
> > - bool enabled)
> > +static void ingenic_adc_enable_unlocked(struct ingenic_adc *adc,
> > + int engine,
> > + bool enabled)
> > {
> > u8 val;
> >
> > - mutex_lock(&adc->lock);
> > val = readb(adc->base + JZ_ADC_REG_ENABLE);
> >
> > if (enabled)
> > @@ -192,20 +191,42 @@ static void ingenic_adc_enable(struct ingenic_adc
> > *adc,
> > val &= ~BIT(engine);
> >
> > writeb(val, adc->base + JZ_ADC_REG_ENABLE);
> > +}
> > +
> > +static void ingenic_adc_enable(struct ingenic_adc *adc,
> > + int engine,
> > + bool enabled)
> > +{
> > + mutex_lock(&adc->lock);
> > + ingenic_adc_enable_unlocked(adc, engine, enabled);
> > mutex_unlock(&adc->lock);
> > }
> >
> > static int ingenic_adc_capture(struct ingenic_adc *adc,
> > int engine)
> > {
> > + u32 cfg;
> > u8 val;
> > int ret;
> >
> > - ingenic_adc_enable(adc, engine, true);
> > + /*
> > + * Disable CMD_SEL temporarily, because it causes wrong VBAT
> > readings,
> > + * probably due to the switch of VREF. We must keep the lock here to
> > + * avoid races with the buffer enable/disable functions.
> > + */
> > + mutex_lock(&adc->lock);
> > + cfg = readl(adc->base + JZ_ADC_REG_CFG);
> > + writel(cfg & ~JZ_ADC_REG_CFG_CMD_SEL, adc->base + JZ_ADC_REG_CFG);
> > +
> > +
> Redundant empty line.
> > + ingenic_adc_enable_unlocked(adc, engine, true);
> > ret = readb_poll_timeout(adc->base + JZ_ADC_REG_ENABLE, val,
> > !(val & BIT(engine)), 250, 1000);
> > if (ret)
> > - ingenic_adc_enable(adc, engine, false);
> > + ingenic_adc_enable_unlocked(adc, engine, false);
> > +
> > + writel(cfg, adc->base + JZ_ADC_REG_CFG);
> > + mutex_unlock(&adc->lock);
> >
> > return ret;
> > }
>
> With the above nitpick corrected:
> Acked-by: Artur Rojek <contact@xxxxxxxxxxxxxx>
>
fixed up whilst applying.

Applied to the fixes-togreg branch of iio.git. Thanks,

Jonathan

>