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

[Russell King - ARM Linux <linux@arm.linux.org.uk>]

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));

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