Messages in this thread | | | Date | Sun, 17 Sep 2023 11:45:52 +0100 | From | Jonathan Cameron <> | Subject | Re: [PATCH] iio: adc: ti_am335x_adc: Make DMAs optional |
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On Thu, 14 Sep 2023 14:13:00 +0200 Wadim Egorov <w.egorov@phytec.de> wrote:
> DMAs are optional. Even if the DMA request is unsuccessfully, > the ADC can still work properly.
> Make tiadc_request_dma() not fail if we do not provide dmas & > dma-names properties. > > This actually fixes the wrong error handling of the tiadc_request_dma() > result where the probing only failed if -EPROPE_DEFER was returned. > > Fixes: f438b9da75eb ("drivers: iio: ti_am335x_adc: add dma support") > No line break here. Fixes tag is part of the main tag block. > Signed-off-by: Wadim Egorov <w.egorov@phytec.de>
> --- > drivers/iio/adc/ti_am335x_adc.c | 7 +++++-- > 1 file changed, 5 insertions(+), 2 deletions(-) > > diff --git a/drivers/iio/adc/ti_am335x_adc.c b/drivers/iio/adc/ti_am335x_adc.c > index 8db7a01cb5fb..e14aa9254ab1 100644 > --- a/drivers/iio/adc/ti_am335x_adc.c > +++ b/drivers/iio/adc/ti_am335x_adc.c > @@ -543,8 +543,11 @@ static int tiadc_request_dma(struct platform_device *pdev, > if (IS_ERR(dma->chan)) { > int ret = PTR_ERR(dma->chan); > > + if (ret != -ENODEV) > + return dev_err_probe(&pdev->dev, ret, > + "RX DMA channel request failed\n"); > dma->chan = NULL; > - return ret; > + return 0; > } > > /* RX buffer */ > @@ -670,7 +673,7 @@ static int tiadc_probe(struct platform_device *pdev) > platform_set_drvdata(pdev, indio_dev); > > err = tiadc_request_dma(pdev, adc_dev); > - if (err && err == -EPROBE_DEFER) > + if (err)
So this looks like a more subtle change than you are describing. In the original code, we backed off only if the return was a PROBE_DEFER, otherwise we carried on.
Your change seems to make that happen for any non -ENODEV error, including PROBE_DEFER. That's fine, but it's not what the description implies.
Whilst tiadc_request_dma will fail today if the dmas etc is not provided, that seems like correct behavior to me. A function requesting dma fails if it isn't available. The handling of whether to carry on the job for the caller.
So I think it should just be if (err && err != -EINVAL) goto err_dma;
and no change in tiadc_request_dma()
However, the case you describe should have worked find with existing code as it wasn't -EPROBE_DEFER, so I don't understand why you were looking at this code block in the first place?
Jonathan
> goto err_dma; > > return 0;
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