Re: [RFC PATCH v1 24/40] metag: DMA

[Arnd Bergmann <arnd@arndb.de>]

On Friday 23 November 2012, James Hogan wrote:
> 
> On 09/11/12 14:25, Arnd Bergmann wrote:
> > On Wednesday 31 October 2012, James Hogan wrote:
> >> +static inline void
> >> +dma_unmap_single(struct device *dev, dma_addr_t dma_addr, size_t size,
> >> +                enum dma_data_direction direction)
> >> +{
> >> +       BUG_ON(!valid_dma_direction(direction));
> >> +       dma_sync_for_cpu((void *)bus_to_virt(dma_addr), size, direction);
> >> +}
> > 
> > bus_to_virt is deprecated an should not be visible to device drivers
> > any more for new stuff. Maybe you can remove the definition and introduce
> > a __bus_to_virt() function for internal use that also returns a pointer
> > type instead.
> 
> Is there any reason not to just directly use phys_to_virt (which
> bus_to_virt was defined as before)?

That should be fine in this case. It's just that device drivers must
not rely directly on a particular mapping between bus and virt addresses.
dma_map_single is are the right place to put this mapping.

	Arnd