From: Jonathan Cameron <jic23@kernel.org>
To: <g.ottinger@abatec.at>
Cc: <eugen.hristev@microchip.com>, <s.etzlstorfer@abatec.at>,
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>,
Maxime Ripard <maxime.ripard@bootlin.com>
Subject: Re: [PATCH] iio: adc: at91: disable adc channel interrupt in timeout case
Date: Sat, 2 Feb 2019 10:20:48 +0000 [thread overview]
Message-ID: <20190202102021.12bb0a72@archlinux> (raw)
In-Reply-To: <20190130134202.5831-1-g.ottinger@abatec.at>
On Wed, 30 Jan 2019 14:42:02 +0100
<g.ottinger@abatec.at> wrote:
> 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>
Whilst I agree this looks like a correct change, I would like Maxime
to take a look as he is obviously much more familiar with the driver
than I am.
I suspect you can only actually get there in the event of a hardware
failure as that isn't actually a timeout you should ever see.
Could be wrong though!
Thanks,
Jonathan
> ---
> 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;
next prev parent reply other threads:[~2019-02-02 10:20 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-01-30 13:42 [PATCH] iio: adc: at91: disable adc channel interrupt in timeout case g.ottinger
2019-02-02 10:20 ` Jonathan Cameron [this message]
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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