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SubjectRe: [PATCH] ARM: Gemini: Add support for PCI BUS
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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