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. > >> >>> >>> 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