Messages in this thread Patch in this message | | | Date | Mon, 5 May 2014 17:43:24 -0400 | From | Santosh Shilimkar <> | Subject | Re: [PATCH v3 5/7] ARM: dma: Use dma_pfn_offset for dma address translation |
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On Monday 05 May 2014 03:50 PM, Russell King - ARM Linux wrote: > 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); > Thanks a lot Russell. Updated patch below for archive records.
From 97a6f063270265d03ffcb010b9dc156b274631e7 Mon Sep 17 00:00:00 2001 From: Grygorii Strashko <grygorii.strashko@ti.com> Date: Thu, 24 Apr 2014 11:30:05 -0400 Subject: [PATCH v3 5/7] ARM: dma: Use dma_pfn_offset for dma address translation
In most of cases DMA addresses can be performed using offset value of Bus address space relatively to physical address space as following:
PFN->DMA: __pfn_to_phys(pfn + [-]dma_pfn_offset)
DMA->PFN: __phys_to_pfn(dma_addr) + [-]dma_pfn_offset
Thanks to Russell King for suggesting the optimised macro's for conversion.
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Cc: Russell King <linux@arm.linux.org.uk> Cc: Arnd Bergmann <arnd@arndb.de> Cc: Olof Johansson <olof@lixom.net> Cc: Grant Likely <grant.likely@linaro.org> Cc: Catalin Marinas <catalin.marinas@arm.com> Cc: Linus Walleij <linus.walleij@linaro.org> Reviewed-by: Rob Herring <robh@kernel.org> Signed-off-by: Grygorii Strashko <grygorii.strashko@ti.com> Signed-off-by: Santosh Shilimkar <santosh.shilimkar@ti.com> --- arch/arm/include/asm/dma-mapping.h | 18 +++++++++++++++++- 1 file changed, 17 insertions(+), 1 deletion(-)
diff --git a/arch/arm/include/asm/dma-mapping.h b/arch/arm/include/asm/dma-mapping.h index e701a4d..b0c79fd 100644 --- a/arch/arm/include/asm/dma-mapping.h +++ b/arch/arm/include/asm/dma-mapping.h @@ -58,21 +58,37 @@ 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) { + 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); + 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) { + 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) { + if (dev) + return pfn_to_dma(dev, virt_to_pfn(addr)); + return (dma_addr_t)__virt_to_bus((unsigned long)(addr)); } -- 1.7.9.5
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