Hi Peter,
On Mon, Jan 20, 2020 at 1:09 PM Peter Ujfalusi <peter.ujfalusi@xxxxxx> wrote:
> On 20/01/2020 14.05, Geert Uytterhoeven wrote:
> > On Tue, Dec 17, 2019 at 11:41 AM Peter Ujfalusi <peter.ujfalusi@xxxxxx> 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>
> >
> > Reviewed-by: Geert Uytterhoeven <geert+renesas@xxxxxxxxx>
> >
> > One comment below.
> >
> >> --- a/drivers/media/platform/rcar_drif.c
> >> +++ b/drivers/media/platform/rcar_drif.c
> >> @@ -275,10 +275,10 @@ static int rcar_drif_alloc_dmachannels(struct rcar_drif_sdr *sdr)
> >> for_each_rcar_drif_channel(i, &sdr->cur_ch_mask) {
> >> struct rcar_drif *ch = sdr->ch[i];
> >>
> >> - ch->dmach = dma_request_slave_channel(&ch->pdev->dev, "rx");
> >> - if (!ch->dmach) {
> >> + ch->dmach = dma_request_chan(&ch->pdev->dev, "rx");
> >> + if (IS_ERR(ch->dmach)) {
> >> rdrif_err(sdr, "ch%u: dma channel req failed\n", i);
> >
> > Now there is an error code, you might (1) want to print it, and (2) only
> > do so when it is not due to probe deferral:
> >
> > if (PTR_ERR(ch->dmach) != -EPROBE_DEFER)
> > rdrif_err(sdr, "ch%u: dma channel req failed %pe\n",
> > i, ch->dmach);
>
> Yes, this is true.
>
> >
> >> - ret = -ENODEV;
> >> + ret = PTR_ERR(ch->dmach);
>
> if (ret != -EPROBE_DEFER)
> rdrif_err(sdr, "ch%u: dma channel req failed (%d)\n", i, ret);
>
> might be simpler.
Sure, checking ret is simpler.
But printing ch->dmach means you can use the new %pe format specifier
to pretty-print the error code.
Gr{oetje,eeting}s,
Geert
--
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@xxxxxxxxxxxxxx
In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
-- Linus Torvalds
