Re: [PATCH 2/5] i2c: sh_mobile: add DMA support

[Geert Uytterhoeven <geert-Td1EMuHUCqxL1ZNQvxDV9g@public.gmane.org>]

Hi Wolfram,

On Mon, Dec 15, 2014 at 10:06 AM, Wolfram Sang <wsa-z923LK4zBo2bacvFa/9K2g@public.gmane.org> wrote:
>> Solutions under consideration:
>>   1. Wolfram posted a patch to make i2c-sh_mobile fall back to PIO,
>>   and retry DMA initialization in every request, so it will switch to
>>   DMA when it becomes available. But this is suboptimal, as it adds
>>   overhead to every request (and DMA may never become available in
>>   case 2).
>
> Still, I'd think I should repost my patches with your comments
> addressed. It does add a bit of overhead IF the dmaengine core is
> compiled in AND the driver for the DMA hardware is not. Well, yeah. On
> the other hand, it fixes the regression that the driver is not even
> loaded in that case (because it currently will be deferred endlessly).
>
> What do you think?

I think it doesn't hurt to repost, now more people understand the intrinsics
of the problem.

Gr{oetje,eeting}s,

                        Geert

--
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert-Td1EMuHUCqxL1ZNQvxDV9g@public.gmane.org

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