Messages in this thread Patch in this message | | | Subject | Re: [PATCH] mfd: stm32-timers: Use dma_request_chan() instead dma_request_slave_channel() | From | Fabrice Gasnier <> | Date | Fri, 20 Dec 2019 09:54:01 +0100 |
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On 12/17/19 11:52 AM, 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@ti.com> > --- > drivers/mfd/stm32-timers.c | 31 ++++++++++++++++++++++--------- > 1 file changed, 22 insertions(+), 9 deletions(-) > > diff --git a/drivers/mfd/stm32-timers.c b/drivers/mfd/stm32-timers.c > index efcd4b980c94..34747e8a4a40 100644 > --- a/drivers/mfd/stm32-timers.c > +++ b/drivers/mfd/stm32-timers.c > @@ -167,10 +167,11 @@ static void stm32_timers_get_arr_size(struct stm32_timers *ddata) > regmap_write(ddata->regmap, TIM_ARR, 0x0); > } > > -static void stm32_timers_dma_probe(struct device *dev, > +static int stm32_timers_dma_probe(struct device *dev, > struct stm32_timers *ddata) > { > int i; > + int ret = 0; > char name[4]; > > init_completion(&ddata->dma.completion); > @@ -179,14 +180,22 @@ static void stm32_timers_dma_probe(struct device *dev, > /* Optional DMA support: get valid DMA channel(s) or NULL */ > for (i = STM32_TIMERS_DMA_CH1; i <= STM32_TIMERS_DMA_CH4; i++) { > snprintf(name, ARRAY_SIZE(name), "ch%1d", i + 1); > - ddata->dma.chans[i] = dma_request_slave_channel(dev, name); > + ddata->dma.chans[i] = dma_request_chan(dev, name); > } > - ddata->dma.chans[STM32_TIMERS_DMA_UP] = > - dma_request_slave_channel(dev, "up"); > - ddata->dma.chans[STM32_TIMERS_DMA_TRIG] = > - dma_request_slave_channel(dev, "trig"); > - ddata->dma.chans[STM32_TIMERS_DMA_COM] = > - dma_request_slave_channel(dev, "com"); > + ddata->dma.chans[STM32_TIMERS_DMA_UP] = dma_request_chan(dev, "up"); > + ddata->dma.chans[STM32_TIMERS_DMA_TRIG] = dma_request_chan(dev, "trig"); > + ddata->dma.chans[STM32_TIMERS_DMA_COM] = dma_request_chan(dev, "com"); > + > + for (i = STM32_TIMERS_DMA_CH1; i < STM32_TIMERS_MAX_DMAS; i++) { > + if (IS_ERR(ddata->dma.chans[i])) { > + if (PTR_ERR(ddata->dma.chans[i]) == -EPROBE_DEFER)> + ret = -EPROBE_DEFER;
Hi Peter,
Thanks for the patch,
As the DMA is optional, I'd rather prefer to check explicitly there's no device, and return any other error case, basically:
if (PTR_ERR(ddata->dma.chans[i]) != -ENODEV) return PTR_ERR(ddata->dma.chans[i]);
> + > + ddata->dma.chans[i] = NULL; > + } > + } > + > + return ret;
With that, return 0 here.
> } > > static void stm32_timers_dma_remove(struct device *dev, > @@ -230,7 +239,11 @@ static int stm32_timers_probe(struct platform_device *pdev) > > stm32_timers_get_arr_size(ddata); > > - stm32_timers_dma_probe(dev, ddata); > + ret = stm32_timers_dma_probe(dev, ddata); > + if (ret) { > + stm32_timers_dma_remove(dev, ddata);
With that, stm32_timers_dma_remove() likely need to be updated:
- if (ddata->dma.chans[i]) + if (!IS_ERR_OR_NULL(ddata->dma.chans[i])) dma_release_channel(ddata->dma.chans[i]);
Best regards, Fabrice
> + return ret; > + } > > platform_set_drvdata(pdev, ddata); > >
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