3.16.72-rc1 review patch. If anyone has any objections, please let me know.
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From: Georg Ottinger g.ottinger@abatec.at
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 Signed-off-by: Jonathan Cameron Jonathan.Cameron@huawei.com Signed-off-by: Ben Hutchings ben@decadent.org.uk --- drivers/iio/adc/at91_adc.c | 28 +++++++++++++++++----------- 1 file changed, 17 insertions(+), 11 deletions(-)
--- a/drivers/iio/adc/at91_adc.c +++ b/drivers/iio/adc/at91_adc.c @@ -702,23 +702,29 @@ static int at91_adc_read_raw(struct iio_ 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;