On Mon, 9 Mar 2020 11:39:17 +0100
Fabrice Gasnier <fabrice.gasnier@xxxxxx> wrote:
> On 3/9/20 11:02 AM, Olivier Moysan 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.
> >
> > Fixes: 2763ea0585c9 ("iio: adc: stm32: add optional dma support")
> >
> > Signed-off-by: Olivier Moysan <olivier.moysan@xxxxxx>
>
> Hi Olivier,
>
> Acked-by: Fabrice Gasnier <fabrice.gasnier@xxxxxx>
Thanks. Queued up locally but not pushed out just yet as I have a pull
request out to Greg. Also marked for stable.
thanks,
Jonathan
>
> Thanks,
> Fabrice
>
> > ---
> > Changes in v2:
> > - Add "Fixes" tag in commit message
> >
> > 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");
> >
