iio: adc: stm32-dfsdm: fix sleep in atomic context

This commit fixes the error message:
"BUG: sleeping function called from invalid context at kernel/irq/chip.c"
Suppress the trigger irq handler. Make the buffer transfers directly
in DMA callback, instead.
Push buffers without timestamps, as timestamps are not supported
in DFSDM driver.

Fixes: 11646e81d775 ("iio: adc: stm32-dfsdm: add support for buffer modes")

Signed-off-by: Olivier Moysan <olivier.moysan@st.com>
Cc: <Stable@vger.kernel.org>
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>

diff --git a/drivers/iio/adc/stm32-dfsdm-adc.c b/drivers/iio/adc/stm32-dfsdm-adc.c
index 2aad2cd..76a60d9 100644 (file)
--- a/drivers/iio/adc/stm32-dfsdm-adc.c
+++ b/drivers/iio/adc/stm32-dfsdm-adc.c
@@ -842,31 +842,6 @@ static inline void stm32_dfsdm_process_data(struct stm32_dfsdm_adc *adc,
        }
 }
 
-static irqreturn_t stm32_dfsdm_adc_trigger_handler(int irq, void *p)
-{
-       struct iio_poll_func *pf = p;
-       struct iio_dev *indio_dev = pf->indio_dev;
-       struct stm32_dfsdm_adc *adc = iio_priv(indio_dev);
-       int available = stm32_dfsdm_adc_dma_residue(adc);
-
-       while (available >= indio_dev->scan_bytes) {
-               s32 *buffer = (s32 *)&adc->rx_buf[adc->bufi];
-
-               stm32_dfsdm_process_data(adc, buffer);
-
-               iio_push_to_buffers_with_timestamp(indio_dev, buffer,
-                                                  pf->timestamp);
-               available -= indio_dev->scan_bytes;
-               adc->bufi += indio_dev->scan_bytes;
-               if (adc->bufi >= adc->buf_sz)
-                       adc->bufi = 0;
-       }
-
-       iio_trigger_notify_done(indio_dev->trig);
-
-       return IRQ_HANDLED;
-}
-
 static void stm32_dfsdm_dma_buffer_done(void *data)
 {
        struct iio_dev *indio_dev = data;
@@ -874,11 +849,6 @@ static void stm32_dfsdm_dma_buffer_done(void *data)
        int available = stm32_dfsdm_adc_dma_residue(adc);
        size_t old_pos;
 
-       if (indio_dev->currentmode & INDIO_BUFFER_TRIGGERED) {
-               iio_trigger_poll_chained(indio_dev->trig);
-               return;
-       }
-
        /*
         * FIXME: In Kernel interface does not support cyclic DMA buffer,and
         * offers only an interface to push data samples per samples.
@@ -906,7 +876,15 @@ static void stm32_dfsdm_dma_buffer_done(void *data)
                        adc->bufi = 0;
                        old_pos = 0;
                }
-               /* regular iio buffer without trigger */
+               /*
+                * 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).
+                */
                if (adc->dev_data->type == DFSDM_IIO)
                        iio_push_to_buffers(indio_dev, buffer);
        }
@@ -1536,8 +1514,7 @@ static int stm32_dfsdm_adc_init(struct iio_dev *indio_dev)
        }
 
        ret = iio_triggered_buffer_setup(indio_dev,
-                                        &iio_pollfunc_store_time,
-                                        &stm32_dfsdm_adc_trigger_handler,
+                                        &iio_pollfunc_store_time, NULL,
                                         &stm32_dfsdm_buffer_setup_ops);
        if (ret) {
                stm32_dfsdm_dma_release(indio_dev);