This is a note to let you know that I've just added the patch titled
iio: adc: at91: disable adc channel interrupt in timeout case
to my staging git tree which can be found at git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/staging.git in the staging-linus branch.
The patch will show up in the next release of the linux-next tree (usually sometime within the next 24 hours during the week.)
The patch will hopefully also be merged in Linus's tree for the next -rc kernel release.
If you have any questions about this process, please let me know.
From 09c6bdee51183a575bf7546890c8c137a75a2b44 Mon Sep 17 00:00:00 2001
From: Georg Ottinger g.ottinger@abatec.at Date: Wed, 30 Jan 2019 14:42:02 +0100 Subject: iio: adc: at91: disable adc channel interrupt in timeout case
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 --- drivers/iio/adc/at91_adc.c | 28 +++++++++++++++++----------- 1 file changed, 17 insertions(+), 11 deletions(-)
diff --git a/drivers/iio/adc/at91_adc.c b/drivers/iio/adc/at91_adc.c index 75d2f73582a3..596841a3c4db 100644 --- a/drivers/iio/adc/at91_adc.c +++ b/drivers/iio/adc/at91_adc.c @@ -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;