Re: [PATCH v2] sh: Update dma-sh api

[Paul Mundt <lethal@linux-sh.org>]

On Tue, Mar 10, 2009 at 01:48:14PM +0900, Nobuhiro Iwamatsu wrote:
> diff --git a/arch/sh/include/asm/dma.h b/arch/sh/include/asm/dma.h
> index beca712..085e05a 100644
> --- a/arch/sh/include/asm/dma.h
> +++ b/arch/sh/include/asm/dma.h
> @@ -23,12 +23,8 @@
>  /* But... */
>  /* XXX: This is not applicable to SuperH, just needed for alloc_bootmem */
>  #define MAX_DMA_ADDRESS		(PAGE_OFFSET+0x10000000)
> -
> -#ifdef CONFIG_NR_DMA_CHANNELS
> -#  define MAX_DMA_CHANNELS	(CONFIG_NR_DMA_CHANNELS)
> -#else
> -#  define MAX_DMA_CHANNELS	(CONFIG_NR_ONCHIP_DMA_CHANNELS)
> -#endif
> +/* MAX DMA Channel */
> +#define MAX_DMA_CHANNELS	(CONFIG_NR_ONCHIP_DMA_CHANNELS)
> 
This breaks the Dreamcast, which contains multiple DMACs and needs more
than the on-chip channels managed by the DMA API. As the Dreamcast is the
primary user of this code, please make sure you do not break its use of
the API. It would also be good if someone can verify whether the G2 and
PVR2 DMA still work after this patch is applied.

On the other hand, I don't know how much we really want to be doing here
in the first place. All new development should be happening on the
dmaengine API instead, this code is mostly for keeping the existing users
limping along, and not much else. Matt Fleming was doing some work there,
it would be preferable to see that code updated and merged rather than
work spent on the old DMA API.