[PATCH 5.14 069/151] iio: adc: ad7780: Fix IRQ flag

[Greg Kroah-Hartman]

From: Alexandru Tachici <alexandru.tachici@xxxxxxxxxx>

commit e081102f3077aa716974ccebec97003c890d5641 upstream.

Correct IRQ flag here is falling.

In Sigma-Delta devices the SDO line is also used as an interrupt.
Leaving IRQ on level instead of falling might trigger a sample read
when the IRQ is enabled, as the SDO line is already low. Not sure
if SDO line will always immediately go high in ad_sd_buffer_postenable
before the IRQ is enabled.

Also the datasheet seem to explicitly say the falling edge of the SDO
should be used as an interrupt:
>From the AD7780 datasheet: " The DOUT/Figure 22 RDY falling edge
can be used as an interrupt to a processor"

Fixes: da4d3d6bb9f6 ("iio: adc: ad-sigma-delta: Allow custom IRQ flags")
Signed-off-by: Alexandru Tachici <alexandru.tachici@xxxxxxxxxx>
Cc: <Stable@xxxxxxxxxxxxxxx>
Link: https://lore.kernel.org/r/20210906065630.16325-3-alexandru.tachici@xxxxxxxxxx
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@xxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
 drivers/iio/adc/ad7780.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

--- a/drivers/iio/adc/ad7780.c
+++ b/drivers/iio/adc/ad7780.c
@@ -203,7 +203,7 @@ static const struct ad_sigma_delta_info
 	.set_mode = ad7780_set_mode,
 	.postprocess_sample = ad7780_postprocess_sample,
 	.has_registers = false,
-	.irq_flags = IRQF_TRIGGER_LOW,
+	.irq_flags = IRQF_TRIGGER_FALLING,
 };
 
 #define _AD7780_CHANNEL(_bits, _wordsize, _mask_all)		\