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.gasn...@st.com> --- 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