On Mon, 20 Jun 2011, Russell King - ARM Linux wrote:

On Mon, Jun 20, 2011 at 06:58:45PM +0200, Arnd Bergmann wrote:

quoted

We are also going to change the ARM implementation to always do 32 bit
accesses in readl/writel, but the patch that went into the ehci driver
was correct nonetheless.

Not without someone doing a comparitively large amount of work to analyze
the effect of any change there and make sure that it doesn't have a
negative impact to drivers.

This thread prompted me to investigate a bit.  I have vague memories for 
the reasons why we decided to use plain C for the IO accessors as the 
inline assembly version didn't produce nearly the same code quality.  It 
seems that GCC improved quite a bit there, and from a quick 
investigation, it looks like comparable code is being generated with the 
C and the inline asm versions with a recent enough GCC.  This is 
certainly the case with the version causing issues with packed 
structures.


Nicolas