Messages in this thread | | | Date | Mon, 29 Nov 2010 21:57:23 +0200 | From | Paulius Zaleckas <> | Subject | Re: [PATCH] ARM: Gemini: Add support for PCI BUS |
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On 11/29/2010 09:32 PM, Russell King - ARM Linux wrote: > On Mon, Nov 29, 2010 at 06:05:07PM +0200, Paulius Zaleckas wrote: >> No he really should NOT use readl/writel. The ONLY difference >> between readl/writel and __raw_readl/__raw_writel is endianess >> conversion. __raw_*l is not doing it. Which to use depend only >> on HW. > > Wrong. readl/writel have barriers too to guarantee ordering between > device accesses and memory accesses. (device accesses are already > ordered with respect to themselves.) __raw variants do not > guarantee the relative ordering between memory accesses and device > accesses.
#ifdef CONFIG_ARM_DMA_MEM_BUFFERABLE #define __iormb() rmb() #define __iowmb() wmb() #else #define __iormb() do { } while (0) #define __iowmb() do { } while (0) #endif
CONFIG_ARM_DMA_MEM_BUFFERABLE is NOT defined in this case. I don't see any other barriers. readl does endianess conversion. What to do if you don't need it? Do it one more time?
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