lkml.org 
[lkml]   [2010]   [Nov]   [29]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
From
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?


\
 
 \ /
  Last update: 2010-11-29 20:59    [W:0.055 / U:0.872 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site