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 complete
conversion. This patch provides an option to fix the issue by setting
IRQ_DISABLE_UNLAZY flag.
Signed-off-by: Masahiro Honda <honda@xxxxxxxxxxxxx>
---
v2:
- 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@xxxxxxxxxxxxx/
drivers/iio/adc/Kconfig | 14 ++++++++++++++
drivers/iio/adc/ad_sigma_delta.c | 31 ++++++++++++++++++++++++++-----
2 files changed, 40 insertions(+), 5 deletions(-)
diff --git a/drivers/iio/adc/Kconfig b/drivers/iio/adc/Kconfig
index 45af2302b..78ab6e2d8 100644
--- a/drivers/iio/adc/Kconfig
+++ b/drivers/iio/adc/Kconfig
@@ -21,6 +21,20 @@ config AD_SIGMA_DELTA
select IIO_BUFFER
select IIO_TRIGGERED_BUFFER
+if AD_SIGMA_DELTA
+
+config AD_SIGMA_DELTA_USE_LAZY_IRQ
+ bool "Use lazy IRQ for sigma-delta ADCs"
+ depends on AD_SIGMA_DELTA
+ default n
+ help
+ Some interrupt controllers have data read problem with ADCs depends on
+ AD_SIGMA_DELTA.
+ Say yes here to avoid the problem at the cost of performance overhead.
+ If unsure, say N (but it's safe to say "Y").
+
+endif # if AD_SIGMA_DELTA
+
config AD4130
tristate "Analog Device AD4130 ADC Driver"
depends on SPI
diff --git a/drivers/iio/adc/ad_sigma_delta.c b/drivers/iio/adc/ad_sigma_delta.c
index d8570f620..b9eae1e80 100644
--- a/drivers/iio/adc/ad_sigma_delta.c
+++ b/drivers/iio/adc/ad_sigma_delta.c
@@ -565,6 +565,16 @@ 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;
+
+#ifdef CONFIG_AD_SIGMA_DELTA_USE_LAZY_IRQ
+ irq_clear_status_flags(sigma_delta->spi->irq, IRQ_DISABLE_UNLAZY);
+#endif
+ 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 +594,22 @@ 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);
+#ifdef CONFIG_AD_SIGMA_DELTA_USE_LAZY_IRQ
+ irq_set_status_flags(sigma_delta->spi->irq, IRQ_DISABLE_UNLAZY);
+#endif
+ 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) {
+#ifdef CONFIG_AD_SIGMA_DELTA_USE_LAZY_IRQ
+ irq_clear_status_flags(sigma_delta->spi->irq, IRQ_DISABLE_UNLAZY);
+#endif
+ return ret;
+ }
+
+ ret = devm_add_action_or_reset(dev, ad_sd_free_irq, sigma_delta);
if (ret)
return ret;
--
2.34.1
