Re: [PATCH 1/2] dmaengine: rcar-dmac: add iommu support for slave transfers

["Niklas Söderlund" <niklas.soderlund+renesas@ragnatech.se>]

* Geert Uytterhoeven <geert@linux-m68k.org> [2016-01-11 08:55:48 +0100]:

> Hi Niklas,
>
> On Mon, Jan 11, 2016 at 3:17 AM, Niklas Söderlund
> <niklas.soderlund+renesas@ragnatech.se> wrote:
> > --- a/drivers/dma/sh/rcar-dmac.c
> > +++ b/drivers/dma/sh/rcar-dmac.c
> > @@ -13,6 +13,7 @@
> >  #include <linux/dma-mapping.h>
> >  #include <linux/dmaengine.h>
> >  #include <linux/interrupt.h>
> > +#include <linux/iommu.h>
> >  #include <linux/list.h>
> >  #include <linux/module.h>
> >  #include <linux/mutex.h>
> > @@ -1101,6 +1102,24 @@ rcar_dmac_prep_dma_cyclic(struct dma_chan *chan, dma_addr_t buf_addr,
> >         return desc;
> >  }
> >
> > +static dma_addr_t __rcar_dmac_dma_map(struct dma_chan *chan, phys_addr_t addr,
> > +               size_t size, enum dma_data_direction dir)
> > +{
> > +       struct rcar_dmac_chan *rchan = to_rcar_dmac_chan(chan);
> > +       struct page *page = phys_to_page(addr);
> > +       size_t offset = addr - page_to_phys(page);
> > +       dma_addr_t map = dma_map_page(chan->device->dev, page, offset, size,
> > +                       dir);
> > +
> > +       if (dma_mapping_error(chan->device->dev, map)) {
> > +               dev_err(chan->device->dev, "chan%u: failed to map %zx@%pap",
> > +                               rchan->index, size, &addr);
> > +               return 0;
>
> Zero may be a valid DMA address. Please use DMA_ERROR_CODE instead.

Thanks will fix together with the issue kbuild test robot found.

>
> > +       }
> > +
> > +       return map;
> > +}
>
> Gr{oetje,eeting}s,
>
>                         Geert
>
> --
> Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-m68k.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