From: Benjamin Herrenschmidt <benh@kernel.crashing.org>
To: Alan Cox <alan@lxorguk.ukuu.org.uk>
Cc: Linus Torvalds <torvalds@osdl.org>, Andrew Morton <akpm@osdl.org>,
Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
Petr Vandrovec <vandrove@vc.cvut.cz>
Subject: Re: [PATCH] ppc64: Fix __raw_* IO accessors
Date: Tue, 21 Sep 2004 21:41:59 +1000 [thread overview]
Message-ID: <1095766919.3577.138.camel@gaston> (raw)
In-Reply-To: <1095761113.30931.13.camel@localhost.localdomain>
On Tue, 2004-09-21 at 20:05, Alan Cox wrote:
> 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.
It uses __raw for non-byteswap... The problem is that __raw does both
non-byteswap and non-barriers and there is no simple way to get one
and not the other...
Ben.
next prev parent reply other threads:[~2004-09-21 11:45 UTC|newest]
Thread overview: 21+ messages / expand[flat|nested] mbox.gz Atom feed top
2004-09-21 9:23 [PATCH] ppc64: Fix __raw_* IO accessors Benjamin Herrenschmidt
2004-09-21 10:05 ` Alan Cox
2004-09-21 11:41 ` Benjamin Herrenschmidt [this message]
2004-09-21 19:30 ` Roland Dreier
2004-09-21 19:41 ` Linus Torvalds
2004-09-21 20:55 ` Geert Uytterhoeven
2004-09-21 22:05 ` Roland Dreier
2004-09-21 22:16 ` Linus Torvalds
2004-09-22 1:34 ` Benjamin Herrenschmidt
2004-09-22 18:58 ` Petr Vandrovec
2004-09-23 0:49 ` Benjamin Herrenschmidt
2004-09-23 15:25 ` Petr Vandrovec
2004-09-23 20:26 ` [PATCH] matroxfb big-endian update (was Re: [PATCH] ppc64: Fix __raw_* IO accessors) Petr Vandrovec
2004-09-24 6:25 ` Benjamin Herrenschmidt
2004-09-24 9:53 ` Petr Vandrovec
2004-09-24 16:16 ` Kostas Georgiou
2004-09-25 1:40 ` Benjamin Herrenschmidt
2004-09-23 22:23 ` [PATCH] ppc64: Fix __raw_* IO accessors Benjamin Herrenschmidt
2004-09-22 2:15 ` Paul Mackerras
2004-09-22 7:36 ` Roland Dreier
2004-09-22 1:31 ` Benjamin Herrenschmidt
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