From e081102f3077aa716974ccebec97003c890d5641 Mon Sep 17 00:00:00 2001
From: Alexandru Tachici <alexandru.tachici@analog.com>
Date: Mon, 6 Sep 2021 09:56:29 +0300
Subject: [PATCH] iio: adc: ad7780: Fix IRQ flag
Git-commit: e081102f3077aa716974ccebec97003c890d5641
Patch-mainline: v5.15-rc6
References: git-fixes stable-5.14.14

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@analog.com>
Cc: <Stable@vger.kernel.org>
Link: https://lore.kernel.org/r/20210906065630.16325-3-alexandru.tachici@analog.com
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Acked-by: Takashi Iwai <tiwai@suse.de>

---
 drivers/iio/adc/ad7780.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/iio/adc/ad7780.c b/drivers/iio/adc/ad7780.c
index 42bb952f4738..b6e8c8abf6f4 100644
--- a/drivers/iio/adc/ad7780.c
+++ b/drivers/iio/adc/ad7780.c
@@ -203,7 +203,7 @@ static const struct ad_sigma_delta_info ad7780_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)		\
-- 
2.26.2