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,
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.
>
>>
>> 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
>
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