linux-kernel - [PATCH v2 3/3] iio: adc: ad7793: Fix IRQ flag

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Message-ID: <20210906065630.16325-4-alexandru.tachici@analog.com>
Date:   Mon, 6 Sep 2021 09:56:30 +0300
From:   <alexandru.tachici@...log.com>
To:     <linux-iio@...r.kernel.org>, <linux-kernel@...r.kernel.org>
CC:     <jic23@...nel.org>
Subject: [PATCH v2 3/3] iio: adc: ad7793: Fix IRQ flag

From: Alexandru Tachici <alexandru.tachici@...log.com>

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 imediately 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 AD7793 datasheet: " The DOUT/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@...log.com>
---
 drivers/iio/adc/ad7793.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/iio/adc/ad7793.c b/drivers/iio/adc/ad7793.c
index ef3e2d3ecb0c..0e7ab3fb072a 100644
--- a/drivers/iio/adc/ad7793.c
+++ b/drivers/iio/adc/ad7793.c
@@ -206,7 +206,7 @@ static const struct ad_sigma_delta_info ad7793_sigma_delta_info = {
 	.has_registers = true,
 	.addr_shift = 3,
 	.read_mask = BIT(6),
-	.irq_flags = IRQF_TRIGGER_LOW,
+	.irq_flags = IRQF_TRIGGER_FALLING,
 };
 
 static const struct ad_sd_calib_data ad7793_calib_arr[6] = {
-- 
2.25.1