Re: [PATCH v3 5/7] ARM: dma: Use dma_pfn_offset for dma address translation
From: Russell King - ARM Linux <hidden>
Date: 2014-05-02 15:00:01
Also in:
linux-arm-kernel, lkml
On Thu, Apr 24, 2014 at 11:30:05AM -0400, Santosh Shilimkar wrote:
quoted hunk ↗ jump to hunk
diff --git a/arch/arm/include/asm/dma-mapping.h b/arch/arm/include/asm/dma-mapping.h index e701a4d..424fda9 100644 --- a/arch/arm/include/asm/dma-mapping.h +++ b/arch/arm/include/asm/dma-mapping.h@@ -58,22 +58,35 @@ static inline int dma_set_mask(struct device *dev, u64 mask) #ifndef __arch_pfn_to_dma static inline dma_addr_t pfn_to_dma(struct device *dev, unsigned long pfn) { - return (dma_addr_t)__pfn_to_bus(pfn); + if (!dev) + return (dma_addr_t)__pfn_to_bus(pfn); + else + return (dma_addr_t)__pfn_to_bus(pfn - dev->dma_pfn_offset);
I really don't trust gcc to do this right, so I think it would be better to make life easier on the compiler: if (dev) pfn -= dev->dma_pfn_offset; return (dma_addr_t)__pfn_to_bus(pfn);
static inline unsigned long dma_to_pfn(struct device *dev, dma_addr_t addr)
{
- return __bus_to_pfn(addr);
+ if (!dev)
+ return __bus_to_pfn(addr);
+ else
+ return __bus_to_pfn(addr) + dev->dma_pfn_offset;and: unsigned long pfn = __bus_to_pfn(addr); if (dev) pfn += dev->dma_pfn_offset; return pfn;
}
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?
}
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. -- FTTC broadband for 0.8mile line: now at 9.7Mbps down 460kbps up... slowly improving, and getting towards what was expected from it.