4.4-stable review patch. If anyone has any objections, please let me know.
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From: Eugen Hristev eugen.hristev@microchip.com
commit bc1b45326223e7e890053cf6266357adfa61942d upstream.
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@bootlin.com Signed-off-by: Eugen Hristev eugen.hristev@microchip.com Acked-by: Ludovic Desroches ludovic.desroches@microchip.com Cc: Stable@vger.kernel.org Signed-off-by: Jonathan Cameron Jonathan.Cameron@huawei.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org
--- drivers/iio/adc/at91_adc.c | 2 ++ 1 file changed, 2 insertions(+)
--- a/drivers/iio/adc/at91_adc.c +++ b/drivers/iio/adc/at91_adc.c @@ -276,6 +276,8 @@ static void handle_adc_eoc_trigger(int i 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); }