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

[Geert Uytterhoeven <geert@linux-m68k.org>]

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.

> +       }
> +
> +       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