Enabling CONFIG_DEBUG_ATOMIC_SLEEP=y triggers this BUG message:
BUG: sleeping function called from invalid context at kernel/irq/chip.c...
Call stack is as follows:
- __might_sleep
- handle_nested_irq <-- Expects threaded irq
- iio_trigger_poll_chained
- stm32_adc_dma_buffer_done
- vchan_complete
- tasklet_action_common
- tasklet_action
- __do_softirq <-- DMA completion raises a tasklet
- irq_exit
- __handle_domain_irq <-- DMA IRQ
- gic_handle_irq
IIO expects threaded interrupt context when calling:
- iio_trigger_poll_chained()
Or it expects interrupt context when calling:
- iio_trigger_poll()
This patch triggers an IRQ upon stm32_adc_dma_buffer_done() DMA callback
call, so the IIO trigger poll API gets called from IRQ context.
Fixes: 2763ea0585c9 ("iio: adc: stm32: add optional dma support")
Signed-off-by: Fabrice Gasnier <fabrice.gasnier@xxxxxx>
---
drivers/iio/adc/Kconfig | 1 +
drivers/iio/adc/stm32-adc.c | 32 ++++++++++++++++++++++++++++++--
2 files changed, 31 insertions(+), 2 deletions(-)
diff --git a/drivers/iio/adc/Kconfig b/drivers/iio/adc/Kconfig
index 76db6e5..059407a 100644
--- a/drivers/iio/adc/Kconfig
+++ b/drivers/iio/adc/Kconfig
@@ -775,6 +775,7 @@ config STM32_ADC_CORE
select MFD_STM32_TIMERS
select IIO_STM32_TIMER_TRIGGER
select IIO_TRIGGERED_BUFFER
+ select IRQ_WORK
help
Select this option to enable the core driver for STMicroelectronics
STM32 analog-to-digital converter (ADC).
diff --git a/drivers/iio/adc/stm32-adc.c b/drivers/iio/adc/stm32-adc.c
index 205e169..1aa3189 100644
--- a/drivers/iio/adc/stm32-adc.c
+++ b/drivers/iio/adc/stm32-adc.c
@@ -20,6 +20,7 @@
#include <linux/interrupt.h>
#include <linux/io.h>
#include <linux/iopoll.h>
+#include <linux/irq_work.h>
#include <linux/module.h>
#include <linux/platform_device.h>
#include <linux/pm_runtime.h>
@@ -297,6 +298,7 @@ struct stm32_adc_cfg {
* @smpr_val: sampling time settings (e.g. smpr1 / smpr2)
* @cal: optional calibration data on some devices
* @chan_name: channel name array
+ * @work: irq work used to call trigger poll routine
*/
struct stm32_adc {
struct stm32_adc_common *common;
@@ -320,6 +322,7 @@ struct stm32_adc {
u32 smpr_val[2];
struct stm32_adc_calib cal;
char chan_name[STM32_ADC_CH_MAX][STM32_ADC_CH_SZ];
+ struct irq_work work;
};
struct stm32_adc_diff_channel {
@@ -1473,11 +1476,32 @@ static unsigned int stm32_adc_dma_residue(struct stm32_adc *adc)
return 0;
}
+static void stm32_adc_dma_irq_work(struct irq_work *work)
+{
+ struct stm32_adc *adc = container_of(work, struct stm32_adc, work);
+ struct iio_dev *indio_dev = iio_priv_to_dev(adc);
+
+ /*
+ * iio_trigger_poll calls generic_handle_irq(). So, it requires hard
+ * irq context, and cannot be called directly from dma callback,
+ * dma cb has to schedule this work instead.
+ */
+ iio_trigger_poll(indio_dev->trig);
+}
+
static void stm32_adc_dma_buffer_done(void *data)
{
struct iio_dev *indio_dev = data;
+ struct stm32_adc *adc = iio_priv(indio_dev);
- iio_trigger_poll_chained(indio_dev->trig);
+ /*
+ * Invoques iio_trigger_poll() from hard irq context: We can't
+ * call iio_trigger_poll() nor iio_trigger_poll_chained()
+ * directly from DMA callback (under tasklet e.g. softirq).
+ * They require respectively HW IRQ and threaded IRQ context
+ * as it might sleep.
+ */
+ irq_work_queue(&adc->work);
}
static int stm32_adc_dma_start(struct iio_dev *indio_dev)
@@ -1585,8 +1609,10 @@ static void __stm32_adc_buffer_predisable(struct iio_dev *indio_dev)
if (!adc->dma_chan)
stm32_adc_conv_irq_disable(adc);
- if (adc->dma_chan)
+ if (adc->dma_chan) {
dmaengine_terminate_all(adc->dma_chan);
+ irq_work_sync(&adc->work);
+ }
if (stm32_adc_set_trig(indio_dev, NULL))
dev_err(&indio_dev->dev, "Can't clear trigger\n");
@@ -1872,6 +1898,8 @@ static int stm32_adc_dma_request(struct iio_dev *indio_dev)
if (ret)
goto err_free;
+ init_irq_work(&adc->work, stm32_adc_dma_irq_work);
+
return 0;
err_free:
--
2.7.4
