On Thu, 9 Jan 2020 13:56:14 +0100 Fabrice Gasnier <fabrice.gasnier@xxxxxx> wrote: > On 1/9/20 12:40 PM, Peter Ujfalusi wrote: > > > > > > On 09/01/2020 13.29, Fabrice Gasnier wrote: > >> On 1/9/20 11:32 AM, Peter Ujfalusi wrote: > >>> > >>> > >>> On 09/01/2020 11.13, Fabrice Gasnier wrote: > >>>> On 1/7/20 12:45 PM, Peter Ujfalusi wrote: > >>>>> dma_request_slave_channel() is a wrapper on top of dma_request_chan() > >>>>> eating up the error code. > >>>>> > >>>>> By using dma_request_chan() directly the driver can support deferred > >>>>> probing against DMA. > >>>>> > >>>>> Signed-off-by: Peter Ujfalusi <peter.ujfalusi@xxxxxx> > >>>>> --- > >>>>> Hi, > >>>>> > >>>>> Changes since v1: > >>>>> - Fall back to IRQ mode for ADC only in case of ENODEV > >>>> > >>>> Hi Peter, > >>>> > >>>> Thanks for the patch, > >>>> > >>>> Please find a minor comment here after. Apart from that, you can add my: > >>>> > >>>> Acked-by: Fabrice Gasnier <fabrice.gasnier@xxxxxx> > >>>> > >>>> > >>>>> > >>>>> Regards, > >>>>> Peter > >>>>> > >>>>> drivers/iio/adc/stm32-dfsdm-adc.c | 21 +++++++++++++++++---- > >>>>> 1 file changed, 17 insertions(+), 4 deletions(-) > >>>>> > >>>>> diff --git a/drivers/iio/adc/stm32-dfsdm-adc.c b/drivers/iio/adc/stm32-dfsdm-adc.c > >>>>> index e493242c266e..74a2211bdff4 100644 > >>>>> --- a/drivers/iio/adc/stm32-dfsdm-adc.c > >>>>> +++ b/drivers/iio/adc/stm32-dfsdm-adc.c > >>>>> @@ -1383,9 +1383,13 @@ static int stm32_dfsdm_dma_request(struct iio_dev *indio_dev) > >>>>> { > >>>>> struct stm32_dfsdm_adc *adc = iio_priv(indio_dev); > >>>>> > >>>>> - adc->dma_chan = dma_request_slave_channel(&indio_dev->dev, "rx"); > >>>>> - if (!adc->dma_chan) > >>>>> - return -EINVAL; > >>>>> + adc->dma_chan = dma_request_chan(&indio_dev->dev, "rx"); > >>>>> + if (IS_ERR(adc->dma_chan)) { > >>>>> + int ret = PTR_ERR(adc->dma_chan); > >>>>> + > >>>>> + adc->dma_chan = NULL; > >>>>> + return ret; > >>>> > >>>> You may "return PTR_ERR(adc->dma_chan);" directly here. > >>> > >>> I don't make decision here on behalf of the adc path on to go forward w/ > >>> or w/o DMA support and if we go ahead the stm32_dfsdm_dma_release() > >>> needs the dma_chan to be NULL in case we don't use DMA. > >>> > >>> It is much cleaner to set dma_chan to NULL here than doing it in other > >>> paths. > >> > >> Hi Peter, > > > > Hi Fabrice, > > > >> Sorry I wasn't clear enough. I agree with you. I was suggesting only, > >> talking about the 'ret' variable. It may be removed to spare a few lines > >> :-). > >> if (IS_ERR(adc->dma_chan)) { > >> adc->dma_chan = NULL; > >> return PTR_ERR(adc->dma_chan); > >> } > >> I'm okay both ways. > > > > PTR_ERR(NULL); will return 0 > > I need to retrieve the actual error code before NULLing dma_chan. > > Oh yes, so please forget this. > Thanks, > Fabrice Applied to the togreg branch of iio.git and pushed out as testing. Note I'll need to rebase once Greg pushes out staging/staging-next with the changes currently in staging/staging-testing. Shouldn't have an effect on this though! Thanks, Jonathan > > > > >> > >>> > >>>> > >>>> Best Regards, > >>>> Fabrice > >>>> > >>>>> + } > >>>>> > >>>>> adc->rx_buf = dma_alloc_coherent(adc->dma_chan->device->dev, > >>>>> DFSDM_DMA_BUFFER_SIZE, > >>>>> @@ -1509,7 +1513,16 @@ static int stm32_dfsdm_adc_init(struct iio_dev *indio_dev) > >>>>> init_completion(&adc->completion); > >>>>> > >>>>> /* Optionally request DMA */ > >>>>> - if (stm32_dfsdm_dma_request(indio_dev)) { > >>>>> + ret = stm32_dfsdm_dma_request(indio_dev); > >>>>> + if (ret) { > >>>>> + if (ret != -ENODEV) { > >>>>> + if (ret != -EPROBE_DEFER) > >>>>> + dev_err(&indio_dev->dev, > >>>>> + "DMA channel request failed with %d\n", > >>>>> + ret); > >>>>> + return ret; > >>>>> + } > >>>>> + > >>>>> dev_dbg(&indio_dev->dev, "No DMA support\n"); > >>>>> return 0; > >>>>> } > >>>>> > >>> > >>> - Péter > >>> > >>> Texas Instruments Finland Oy, Porkkalankatu 22, 00180 Helsinki. > >>> Y-tunnus/Business ID: 0615521-4. Kotipaikka/Domicile: Helsinki > >>> > > > > - Péter > > > > Texas Instruments Finland Oy, Porkkalankatu 22, 00180 Helsinki. > > Y-tunnus/Business ID: 0615521-4. Kotipaikka/Domicile: Helsinki > >