On Mon, Sep 24, 2018 at 10:51:43AM +0300, Eugen Hristev wrote:
> When doing simple conversions, the driver did not acknowledge the DRDY irq.
> If this irq status is not acked, it will be left pending, and as soon as a
> trigger is enabled, the irq handler will be called, it doesn't know why
> this status has occurred because no channel is pending, and then it will go
> int a irq loop and board will hang.
> To avoid this situation, read the LCDR after a raw conversion is done.
>
> Fixes 0e589d5fb ("ARM: AT91: IIO: Add AT91 ADC driver.")
> Cc: Maxime Ripard <maxime.ripard@xxxxxxxxxxx>
> Signed-off-by: Eugen Hristev <eugen.hristev@xxxxxxxxxxxxx>
Acked-by: Ludovic Desroches <ludovic.desroches@xxxxxxxxxxxxx>
> ---
> Hello Jonathan,
>
> I moved this LCDR read/acknowledge into the IRQ handler after the conversion
> value is being read.
> Sorry about the noise to stable@vger, removed from message.
>
> Thanks,
> Eugen
>
> drivers/iio/adc/at91_adc.c | 2 ++
> 1 file changed, 2 insertions(+)
>
> diff --git a/drivers/iio/adc/at91_adc.c b/drivers/iio/adc/at91_adc.c
> index 44b5168..e3be88e 100644
> --- a/drivers/iio/adc/at91_adc.c
> +++ b/drivers/iio/adc/at91_adc.c
> @@ -279,6 +279,8 @@ static void handle_adc_eoc_trigger(int irq, struct iio_dev *idev)
> iio_trigger_poll(idev->trig);
> } else {
> st->last_value = at91_adc_readl(st, AT91_ADC_CHAN(st, st->chnb));
> + /* Needed to ACK the DRDY interruption */
> + at91_adc_readl(st, AT91_ADC_LCDR);
> st->done = true;
> wake_up_interruptible(&st->wq_data_avail);
> }
> --
> 2.7.4
>
