Re: [PATCH v3 5/7] ARM: dma: Use dma_pfn_offset for dma address translation

Russell King - ARM Linux
2014-05-05T19:51:52Z

On Fri, May 02, 2014 at 11:05:16AM -0400, Santosh Shilimkar wrote:
> On Friday 02 May 2014 10:58 AM, Russell King - ARM Linux wrote:
> > On Thu, Apr 24, 2014 at 11:30:05AM -0400, Santosh Shilimkar wrote:
> >> static inline void *dma_to_virt(struct device *dev, dma_addr_t addr)
> >> {
> >> - return (void *)__bus_to_virt((unsigned long)addr);
> >> + if (!dev)
> >> + return (void *)__bus_to_virt((unsigned long)addr);
> >> + else
> >> + return (void *)__bus_to_virt(__pfn_to_bus(dma_to_pfn(dev, addr)));
> >
> > This is quite horrendous. There's easier ways to do this... I assume
> > you haven't looked at the assembler resulting from this at all with
> > stuff like the p2v patching enabled?
> >
> I haven't. Will check.

if (dev) {
unsigned long pfn = dma_to_pfn(dev, addr);

return phys_to_virt(__pfn_to_phys(pfn));
}

return (void *)__bus_to_virt((unsigned long)addr);

> >> static inline dma_addr_t virt_to_dma(struct device *dev, void *addr)
> >> {
> >> - return (dma_addr_t)__virt_to_bus((unsigned long)(addr));
> >> + if (!dev)
> >> + return (dma_addr_t)__virt_to_bus((unsigned long)(addr));
> >> + else
> >> + return pfn_to_dma(dev,
> >> + __bus_to_pfn(__virt_to_bus((unsigned long)(addr))));
> >
> > Same here.
> >
> ok.

if (dev)
return pfn_to_dma(dev, virt_to_pfn(addr));

return (dma_addr_t)__virt_to_bus((unsigned long)(addr));

--
FTTC broadband for 0.8mile line: now at 9.7Mbps down 460kbps up... slowly
improving, and getting towards what was expected from it.