| Message ID | 20200916070821.118374-1-eugen.hristev@microchip.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | iio: adc: at91-sama5d2_adc: fix DMA conversion crash | expand |
On Wed, 16 Sep 2020 10:08:21 +0300 Eugen Hristev <eugen.hristev@microchip.com> wrote: > After the move of the postenable code to preenable, the DMA start was > done before the DMA init, which is not correct. > The DMA is initialized in set_watermark. Because of this, we need to call > the DMA start functions in set_watermark, after the DMA init, instead of > preenable hook, when the DMA is not properly setup yet. > > Fixes: f3c034f61775 ("iio: at91-sama5d2_adc: adjust iio_triggered_buffer_{predisable,postenable} positions") > Signed-off-by: Eugen Hristev <eugen.hristev@microchip.com> Basic approach looks fine, but if we were to get an error from the buffer_prepare() function, should we be looking to disable dma if we enabled it earlier in the set_watermark callback? > --- > > Hi, > > This crash is in the kernel since 5.8-rc1 > > Please have a look at discussion here: > https://lore.kernel.org/linux-iio/CA+U=DsqRUtjjoe5nevP_wNxTgr27+O2V1h9w7d3QijBQ+5f3XA@mail.gmail.com/T/#t > > Thanks ! > > drivers/iio/adc/at91-sama5d2_adc.c | 11 +++++++---- > 1 file changed, 7 insertions(+), 4 deletions(-) > > diff --git a/drivers/iio/adc/at91-sama5d2_adc.c b/drivers/iio/adc/at91-sama5d2_adc.c > index de9583d6cddd..b5196797dcb8 100644 > --- a/drivers/iio/adc/at91-sama5d2_adc.c > +++ b/drivers/iio/adc/at91-sama5d2_adc.c > @@ -884,7 +884,7 @@ static bool at91_adc_current_chan_is_touch(struct iio_dev *indio_dev) > AT91_SAMA5D2_MAX_CHAN_IDX + 1); > } > > -static int at91_adc_buffer_preenable(struct iio_dev *indio_dev) > +static int at91_adc_buffer_prepare(struct iio_dev *indio_dev) > { > int ret; > u8 bit; > @@ -901,7 +901,7 @@ static int at91_adc_buffer_preenable(struct iio_dev *indio_dev) > /* we continue with the triggered buffer */ > ret = at91_adc_dma_start(indio_dev); > if (ret) { > - dev_err(&indio_dev->dev, "buffer postenable failed\n"); > + dev_err(&indio_dev->dev, "buffer prepare failed\n"); > return ret; > } > > @@ -989,7 +989,6 @@ static int at91_adc_buffer_postdisable(struct iio_dev *indio_dev) > } > > static const struct iio_buffer_setup_ops at91_buffer_setup_ops = { > - .preenable = &at91_adc_buffer_preenable, > .postdisable = &at91_adc_buffer_postdisable, > }; > > @@ -1586,7 +1585,11 @@ static int at91_adc_set_watermark(struct iio_dev *indio_dev, unsigned int val) > else if (val > 1) > at91_adc_dma_init(to_platform_device(&indio_dev->dev)); > > - return 0; > + /* > + * We can start the DMA only after setting the watermark and > + * having the DMA initialization completed > + */ Looks superficially to me like we may need to unwind some stuff if this fails. > + return at91_adc_buffer_prepare(indio_dev); > } > > static int at91_adc_update_scan_mode(struct iio_dev *indio_dev,
diff --git a/drivers/iio/adc/at91-sama5d2_adc.c b/drivers/iio/adc/at91-sama5d2_adc.c index de9583d6cddd..b5196797dcb8 100644 --- a/drivers/iio/adc/at91-sama5d2_adc.c +++ b/drivers/iio/adc/at91-sama5d2_adc.c @@ -884,7 +884,7 @@ static bool at91_adc_current_chan_is_touch(struct iio_dev *indio_dev) AT91_SAMA5D2_MAX_CHAN_IDX + 1); } -static int at91_adc_buffer_preenable(struct iio_dev *indio_dev) +static int at91_adc_buffer_prepare(struct iio_dev *indio_dev) { int ret; u8 bit; @@ -901,7 +901,7 @@ static int at91_adc_buffer_preenable(struct iio_dev *indio_dev) /* we continue with the triggered buffer */ ret = at91_adc_dma_start(indio_dev); if (ret) { - dev_err(&indio_dev->dev, "buffer postenable failed\n"); + dev_err(&indio_dev->dev, "buffer prepare failed\n"); return ret; } @@ -989,7 +989,6 @@ static int at91_adc_buffer_postdisable(struct iio_dev *indio_dev) } static const struct iio_buffer_setup_ops at91_buffer_setup_ops = { - .preenable = &at91_adc_buffer_preenable, .postdisable = &at91_adc_buffer_postdisable, }; @@ -1586,7 +1585,11 @@ static int at91_adc_set_watermark(struct iio_dev *indio_dev, unsigned int val) else if (val > 1) at91_adc_dma_init(to_platform_device(&indio_dev->dev)); - return 0; + /* + * We can start the DMA only after setting the watermark and + * having the DMA initialization completed + */ + return at91_adc_buffer_prepare(indio_dev); } static int at91_adc_update_scan_mode(struct iio_dev *indio_dev,
After the move of the postenable code to preenable, the DMA start was done before the DMA init, which is not correct. The DMA is initialized in set_watermark. Because of this, we need to call the DMA start functions in set_watermark, after the DMA init, instead of preenable hook, when the DMA is not properly setup yet. Fixes: f3c034f61775 ("iio: at91-sama5d2_adc: adjust iio_triggered_buffer_{predisable,postenable} positions") Signed-off-by: Eugen Hristev <eugen.hristev@microchip.com> --- Hi, This crash is in the kernel since 5.8-rc1 Please have a look at discussion here: https://lore.kernel.org/linux-iio/CA+U=DsqRUtjjoe5nevP_wNxTgr27+O2V1h9w7d3QijBQ+5f3XA@mail.gmail.com/T/#t Thanks ! drivers/iio/adc/at91-sama5d2_adc.c | 11 +++++++---- 1 file changed, 7 insertions(+), 4 deletions(-)