From: <g.ottinger@abatec.at>
To: unlisted-recipients:; (no To-header on input)
Cc: <g.ottinger@abatec.at>, <eugen.hristev@microchip.com>,
<s.etzlstorfer@abatec.at>, Jonathan Cameron <jic23@kernel.org>,
Hartmut Knaack <knaack.h@gmx.de>,
Lars-Peter Clausen <lars@metafoo.de>,
Peter Meerwald-Stadler <pmeerw@pmeerw.net>,
Nicolas Ferre <nicolas.ferre@microchip.com>,
Alexandre Belloni <alexandre.belloni@bootlin.com>,
Ludovic Desroches <ludovic.desroches@microchip.com>,
"David S. Miller" <davem@davemloft.net>,
Ard Biesheuvel <ard.biesheuvel@linaro.org>,
Kees Cook <keescook@chromium.org>, <linux-iio@vger.kernel.org>,
<linux-arm-kernel@lists.infradead.org>,
<linux-kernel@vger.kernel.org>
Subject: [PATCH] iio: adc: at91: disable adc channel interrupt in timeout case
Date: Wed, 30 Jan 2019 14:42:02 +0100 [thread overview]
Message-ID: <20190130134202.5831-1-g.ottinger@abatec.at> (raw)
From: Georg Ottinger <g.ottinger@abatec.at>
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>
---
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 75d2f7358..596841a3c 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;
--
2.17.1
next reply other threads:[~2019-01-30 13:57 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-01-30 13:42 g.ottinger [this message]
2019-02-02 10:20 ` [PATCH] iio: adc: at91: disable adc channel interrupt in timeout case Jonathan Cameron
2019-02-04 7:17 ` AW: " Georg Ottinger
2019-02-04 9:45 ` Jonathan Cameron
2019-02-04 11:03 ` AW: " Georg Ottinger
2019-02-22 9:59 ` Ludovic Desroches
2019-03-03 17:17 ` Jonathan Cameron
2019-02-04 11:09 ` AW: " Georg Ottinger
2019-02-22 9:56 ` Ludovic Desroches
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