linux-kernel - [PATCH v5] iio: adc: ad_sigma_delta: Fix IRQ issue by setting IRQ_DISABLE

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Message-Id: <20230518110816.248-1-honda@mechatrax.com>
Date:   Thu, 18 May 2023 20:08:16 +0900
From:   Masahiro Honda <honda@...hatrax.com>
To:     Lars-Peter Clausen <lars@...afoo.de>,
        Michael Hennerich <Michael.Hennerich@...log.com>,
        Jonathan Cameron <jic23@...nel.org>
Cc:     linux-iio@...r.kernel.org, linux-kernel@...r.kernel.org,
        Masahiro Honda <honda@...hatrax.com>
Subject: [PATCH v5] iio: adc: ad_sigma_delta: Fix IRQ issue by setting IRQ_DISABLE_UNLAZY flag

The Sigma-Delta ADCs supported by this driver can use SDO as an interrupt
line to indicate the completion of a conversion. However, some devices
cannot properly detect the completion of a conversion by an interrupt.
This is for the reason mentioned in the following commit.

commit e9849777d0e2 ("genirq: Add flag to force mask in
                      disable_irq[_nosync]()")

A read operation is performed by an extra interrupt before the completion
of a conversion. At this time, the value read from the ADC data register
is the same as the previous conversion result. This patch fixes the issue
by setting IRQ_DISABLE_UNLAZY flag.

Fixes: 0c6ef985a1f ("iio: adc: ad7791: fix IRQ flags")
Fixes: 1a913270e57 ("iio: adc: ad7793: Fix IRQ flag")
Fixes: e081102f307 ("iio: adc: ad7780: Fix IRQ flag")
Fixes: 89a86da5cb8 ("iio: adc: ad7192: Add IRQ flag")
Fixes: 79ef91493f5 ("iio: adc: ad7124: Set IRQ type to falling")
Signed-off-by: Masahiro Honda <honda@...hatrax.com>
---
v5:
 - Fix the patch title.
 - Add fixes tags.
 - Add information about behavior to the commit message.
v4: https://lore.kernel.org/linux-iio/20230502102930.773-1-honda@mechatrax.com/
 - Remove the callback.
v3: https://lore.kernel.org/linux-iio/20230420102316.757-1-honda@mechatrax.com/
 - Remove the Kconfig option.
v2: https://lore.kernel.org/linux-iio/20230414102744.150-1-honda@mechatrax.com/
 - Rework commit message.
 - Add a new entry in the Kconfig.
 - Call irq_clear_status_flags(irq, IRQ_DISABLE_UNLAZY) when freeing the IRQ.
v1: https://lore.kernel.org/linux-iio/20230306044737.862-1-honda@mechatrax.com/

 drivers/iio/adc/ad_sigma_delta.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/drivers/iio/adc/ad_sigma_delta.c b/drivers/iio/adc/ad_sigma_delta.c
index d8570f62078..7e219287074 100644
--- a/drivers/iio/adc/ad_sigma_delta.c
+++ b/drivers/iio/adc/ad_sigma_delta.c
@@ -584,6 +584,10 @@ static int devm_ad_sd_probe_trigger(struct device *dev, struct iio_dev *indio_de
 	init_completion(&sigma_delta->completion);
 
 	sigma_delta->irq_dis = true;
+
+	/* the IRQ core clears IRQ_DISABLE_UNLAZY flag when freeing an IRQ */
+	irq_set_status_flags(sigma_delta->spi->irq, IRQ_DISABLE_UNLAZY);
+
 	ret = devm_request_irq(dev, sigma_delta->spi->irq,
 			       ad_sd_data_rdy_trig_poll,
 			       sigma_delta->info->irq_flags | IRQF_NO_AUTOEN,
-- 
2.34.1