Messages in this thread | | | Date | Mon, 20 Jun 2011 15:29:44 -0400 (EDT) | From | Nicolas Pitre <> | Subject | Re: [PATCH] USB: ehci: use packed, aligned(4) instead of removing the packed attribute |
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On Mon, 20 Jun 2011, Russell King - ARM Linux wrote:
> On Mon, Jun 20, 2011 at 06:58:45PM +0200, Arnd Bergmann wrote: > > 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
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