Re: [PATCH] ppc64: Fix __raw_* IO accessors

Alan Cox
2004-09-21T11:08:12Z

On Maw, 2004-09-21 at 10:23, Benjamin Herrenschmidt wrote:
> Hi !
>
> Linus, I don't know if you did that on purpose, but you removed the
> "volatile" statement from the definition of the __raw_* IO accessors
> on ppc64, which cause some real bad optisations to happen in some
> fbdev's like matroxfb to happen (just imagine that matroxfb loops
> reading an IO register waiting for a bit to change).

Why is it using __raw if it cares about ordering and not using barriers
? Way back when the original definition was that __raw didnt do
barriers. Thats why I2O for example uses __raw_ so that messages can be
generated as efficiently as possible.