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iio: adc: at91: disable adc channel interrupt in timeout case

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commit 09c6bdee51183a575bf7546890c8c137a75a2b44 upstream.

Having a brief look at at91_adc_read_raw() it is obvious that in the case
of a timeout the setting of AT91_ADC_CHDR and AT91_ADC_IDR registers is
omitted. If 2 different channels are queried we can end up with a
situation where two interrupts are enabled, but only one interrupt is
cleared in the interrupt handler. Resulting in a interrupt loop and a
system hang.

Signed-off-by: Georg Ottinger <g.ottinger@abatec.at>
Acked-by: Ludovic Desroches <ludovic.desroches@microchip.com>
Cc: <Stable@vger.kernel.org>
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Georg Ottinger 2019-01-30 14:42:02 +01:00 committed by Greg Kroah-Hartman
parent 36971130bb
commit 98171e1947
1 changed files with 17 additions and 11 deletions
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28
drivers/iio/adc/at91_adc.c
View file

@ -704,23 +704,29 @@ static int at91_adc_read_raw(struct iio_dev *idev,
ret = wait_event_interruptible_timeout(st->wq_data_avail,
st->done,
msecs_to_jiffies(1000));
if (ret == 0)
ret = -ETIMEDOUT;
if (ret < 0) {
mutex_unlock(&st->lock);
return ret;
}
*val = st->last_value;
/* Disable interrupts, regardless if adc conversion was
* successful or not
*/
at91_adc_writel(st, AT91_ADC_CHDR,
AT91_ADC_CH(chan->channel));
at91_adc_writel(st, AT91_ADC_IDR, BIT(chan->channel));
st->last_value = 0;
st->done = false;
if (ret > 0) {
/* a valid conversion took place */
*val = st->last_value;
st->last_value = 0;
st->done = false;
ret = IIO_VAL_INT;
} else if (ret == 0) {
/* conversion timeout */
dev_err(&idev->dev, "ADC Channel %d timeout.\n",
chan->channel);
ret = -ETIMEDOUT;
}
mutex_unlock(&st->lock);
return IIO_VAL_INT;
return ret;
case IIO_CHAN_INFO_SCALE:
*val = st->vref_mv;