2020-01-08 08:18:41

by Peter Ujfalusi

Subject: [PATCH v3] iio: adc: stm32-adc: Use dma_request_chan() instead dma_request_slave_channel()

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 <[email protected]>
Acked-by: Fabrice Gasnier <[email protected]>
---
Hi,

Changes since v2:
- Replace the comment as suggested by Fabrice

Changes since v1:
- Fall back to IRQ mode only in case of ENODEV

Regards,
Peter

drivers/iio/adc/stm32-adc.c | 16 ++++++++++++++--
1 file changed, 14 insertions(+), 2 deletions(-)

diff --git a/drivers/iio/adc/stm32-adc.c b/drivers/iio/adc/stm32-adc.c
index 3b291d72701c..a8d2414ee2eb 100644
--- a/drivers/iio/adc/stm32-adc.c
+++ b/drivers/iio/adc/stm32-adc.c
@@ -1746,9 +1746,21 @@ static int stm32_adc_dma_request(struct iio_dev *indio_dev)
struct dma_slave_config config;
int ret;

- adc->dma_chan = dma_request_slave_channel(&indio_dev->dev, "rx");
- if (!adc->dma_chan)
+ adc->dma_chan = dma_request_chan(&indio_dev->dev, "rx");
+ if (IS_ERR(adc->dma_chan)) {
+ ret = PTR_ERR(adc->dma_chan);
+ if (ret != -ENODEV) {
+ if (ret != -EPROBE_DEFER)
+ dev_err(&indio_dev->dev,
+ "DMA channel request failed with %d\n",
+ ret);
+ return ret;
+ }
+
+ /* DMA is optional: fall back to IRQ mode */
+ adc->dma_chan = NULL;
return 0;
+ }

adc->rx_buf = dma_alloc_coherent(adc->dma_chan->device->dev,
STM32_DMA_BUFFER_SIZE,
--
Peter

Texas Instruments Finland Oy, Porkkalankatu 22, 00180 Helsinki.
Y-tunnus/Business ID: 0615521-4. Kotipaikka/Domicile: Helsinki

2020-01-11 11:02:00

by Jonathan Cameron

Subject: Re: [PATCH v3] iio: adc: stm32-adc: Use dma_request_chan() instead dma_request_slave_channel()

On Wed, 8 Jan 2020 10:08:01 +0200
Peter Ujfalusi <[email protected]> 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 <[email protected]>
> Acked-by: Fabrice Gasnier <[email protected]>

Applied to the togreg branch of iio.git and pushed out as testing.

thanks,

Jonathan

> ---
> Hi,
>
> Changes since v2:
> - Replace the comment as suggested by Fabrice
>
> Changes since v1:
> - Fall back to IRQ mode only in case of ENODEV
>
> Regards,
> Peter
>
> drivers/iio/adc/stm32-adc.c | 16 ++++++++++++++--
> 1 file changed, 14 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/iio/adc/stm32-adc.c b/drivers/iio/adc/stm32-adc.c
> index 3b291d72701c..a8d2414ee2eb 100644
> --- a/drivers/iio/adc/stm32-adc.c
> +++ b/drivers/iio/adc/stm32-adc.c
> @@ -1746,9 +1746,21 @@ static int stm32_adc_dma_request(struct iio_dev *indio_dev)
> struct dma_slave_config config;
> int ret;
>
> - adc->dma_chan = dma_request_slave_channel(&indio_dev->dev, "rx");
> - if (!adc->dma_chan)
> + adc->dma_chan = dma_request_chan(&indio_dev->dev, "rx");
> + if (IS_ERR(adc->dma_chan)) {
> + ret = PTR_ERR(adc->dma_chan);
> + if (ret != -ENODEV) {
> + if (ret != -EPROBE_DEFER)
> + dev_err(&indio_dev->dev,
> + "DMA channel request failed with %d\n",
> + ret);
> + return ret;
> + }
> +
> + /* DMA is optional: fall back to IRQ mode */
> + adc->dma_chan = NULL;
> return 0;
> + }
>
> adc->rx_buf = dma_alloc_coherent(adc->dma_chan->device->dev,
> STM32_DMA_BUFFER_SIZE,