On Fri, 6 Mar 2020 16:53:35 +0100 Olivier Moysan <olivier.moysan@xxxxxx> wrote: > This commit fixes the following error: > "BUG: sleeping function called from invalid context at kernel/irq/chip.c" > > In DMA mode suppress the trigger irq handler, and make the buffer > transfers directly in DMA callback, instead. > > Signed-off-by: Olivier Moysan <olivier.moysan@xxxxxx> looks good to me, but... fixes tag? We probably want to backport this so good to know when we introduced the issue. Thanks, Jonathan > --- > This solution has been already discussed in the thread > https://lkml.org/lkml/2019/3/30/171, and applied in STM32 DFSDM driver: > e19ac9d9a978 ("iio: adc: stm32-dfsdm: fix sleep in atomic context") > --- > drivers/iio/adc/stm32-adc.c | 31 ++++++++++++++++++++++++++++--- > 1 file changed, 28 insertions(+), 3 deletions(-) > > diff --git a/drivers/iio/adc/stm32-adc.c b/drivers/iio/adc/stm32-adc.c > index 80c3f963527b..ae622ee6d08c 100644 > --- a/drivers/iio/adc/stm32-adc.c > +++ b/drivers/iio/adc/stm32-adc.c > @@ -1418,8 +1418,30 @@ static unsigned int stm32_adc_dma_residue(struct stm32_adc *adc) > static void stm32_adc_dma_buffer_done(void *data) > { > struct iio_dev *indio_dev = data; > + struct stm32_adc *adc = iio_priv(indio_dev); > + int residue = stm32_adc_dma_residue(adc); > + > + /* > + * In DMA mode the trigger services of IIO are not used > + * (e.g. no call to iio_trigger_poll). > + * Calling irq handler associated to the hardware trigger is not > + * relevant as the conversions have already been done. Data > + * transfers are performed directly in DMA callback instead. > + * This implementation avoids to call trigger irq handler that > + * may sleep, in an atomic context (DMA irq handler context). > + */ > + dev_dbg(&indio_dev->dev, "%s bufi=%d\n", __func__, adc->bufi); > > - iio_trigger_poll_chained(indio_dev->trig); > + while (residue >= indio_dev->scan_bytes) { > + u16 *buffer = (u16 *)&adc->rx_buf[adc->bufi]; > + > + iio_push_to_buffers(indio_dev, buffer); > + > + residue -= indio_dev->scan_bytes; > + adc->bufi += indio_dev->scan_bytes; > + if (adc->bufi >= adc->rx_buf_sz) > + adc->bufi = 0; > + } > } > > static int stm32_adc_dma_start(struct iio_dev *indio_dev) > @@ -1845,6 +1867,7 @@ static int stm32_adc_probe(struct platform_device *pdev) > { > struct iio_dev *indio_dev; > struct device *dev = &pdev->dev; > + irqreturn_t (*handler)(int irq, void *p) = NULL; > struct stm32_adc *adc; > int ret; > > @@ -1911,9 +1934,11 @@ static int stm32_adc_probe(struct platform_device *pdev) > if (ret < 0) > return ret; > > + if (!adc->dma_chan) > + handler = &stm32_adc_trigger_handler; > + > ret = iio_triggered_buffer_setup(indio_dev, > - &iio_pollfunc_store_time, > - &stm32_adc_trigger_handler, > + &iio_pollfunc_store_time, handler, > &stm32_adc_buffer_setup_ops); > if (ret) { > dev_err(&pdev->dev, "buffer setup failed\n");
