Re: [PATCH V2 03/27] mmc: mmci: convert dma_setup callback to return an int

[Srinivas Kandagatla]

Thanks for looping me!

On 24/09/18 15:28, Ulf Hansson wrote:
> >   /* Initialize the dml hardware connected to SD Card controller */
> > -static void qcom_dma_setup(struct mmci_host *host)
> > +static int qcom_dma_setup(struct mmci_host *host)
> >   {
> >          u32 config;
> >          void __iomem *base;
> > @@ -131,7 +131,7 @@ static void qcom_dma_setup(struct mmci_host *host)
> >
> >          if (producer_id < 0 || consumer_id < 0) {
> >                  host->variant->qcom_dml = false;
> It seems like the existing code is an attempt to fallback to use pio
> mode. However, I doubt it works as is.

If I remember it correctly, Yes, that was the intent. we should still be 
able to use the pio mode if the dma setup fails.

I believe pio mode should work, Last time when I tried (3-4 years back) 
it did work!

> > -               return;
> > +               return -EINVAL;
> My point is, if you return an error code here, it means that the error
> code becomes propagated and ->probe() will fail.
That would be very bad!, We should report it and may be just continue 
with pio mode.

> Ideally, we should be able fall back to pio mode when dma doesn't
> work. I have looped in Srinivas who implemented the qcom dml support,
> let's see if he can explains the intent with the code.
>
> I also volunteer to help out running some tests on the 410c platform,
I think you meant IFC6410.. DB410c uses sdhci.


--srini
> however allow me a day or two to do that.