[PATCH v3] Fix IRQ issue by setting IRQ_DISABLE_UNLAZY flag

[Masahiro Honda <honda@mechatrax.com>]

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. This patch fixes the issue by setting IRQ_DISABLE_UNLAZY
flag.

Signed-off-by: Masahiro Honda <honda@mechatrax.com>
---
v3:
 - 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 | 25 ++++++++++++++++++++-----
 1 file changed, 20 insertions(+), 5 deletions(-)

diff --git a/drivers/iio/adc/ad_sigma_delta.c b/drivers/iio/adc/ad_sigma_delta.c
index d8570f620..215ecbedb 100644
--- a/drivers/iio/adc/ad_sigma_delta.c
+++ b/drivers/iio/adc/ad_sigma_delta.c
@@ -565,6 +565,14 @@ int ad_sd_validate_trigger(struct iio_dev *indio_dev, struct iio_trigger *trig)
 }
 EXPORT_SYMBOL_NS_GPL(ad_sd_validate_trigger, IIO_AD_SIGMA_DELTA);
 
+static void ad_sd_free_irq(void *sd)
+{
+	struct ad_sigma_delta *sigma_delta = sd;
+
+	irq_clear_status_flags(sigma_delta->spi->irq, IRQ_DISABLE_UNLAZY);
+	free_irq(sigma_delta->spi->irq, sigma_delta);
+}
+
 static int devm_ad_sd_probe_trigger(struct device *dev, struct iio_dev *indio_dev)
 {
 	struct ad_sigma_delta *sigma_delta = iio_device_get_drvdata(indio_dev);
@@ -584,11 +592,18 @@ 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;
-	ret = devm_request_irq(dev, sigma_delta->spi->irq,
-			       ad_sd_data_rdy_trig_poll,
-			       sigma_delta->info->irq_flags | IRQF_NO_AUTOEN,
-			       indio_dev->name,
-			       sigma_delta);
+	irq_set_status_flags(sigma_delta->spi->irq, IRQ_DISABLE_UNLAZY);
+	ret = request_irq(sigma_delta->spi->irq,
+			  ad_sd_data_rdy_trig_poll,
+			  sigma_delta->info->irq_flags | IRQF_NO_AUTOEN,
+			  indio_dev->name,
+			  sigma_delta);
+	if (ret) {
+		irq_clear_status_flags(sigma_delta->spi->irq, IRQ_DISABLE_UNLAZY);
+		return ret;
+	}
+
+	ret = devm_add_action_or_reset(dev, ad_sd_free_irq, sigma_delta);
 	if (ret)
 		return ret;
 
-- 
2.34.1