From: Jeremy Higdon <jeremy@sgi.com>
To: Greg KH <greg@kroah.com>
Cc: Jesse Barnes <jbarnes@sgi.com>,
Grant Grundler <grundler@parisc-linux.org>,
Matthew Wilcox <willy@debian.org>,
linux-pci@atrey.karlin.mff.cuni.cz, linux-kernel@vger.kernel.org
Subject: Re: [RFC] Relaxed PIO read vs. DMA write ordering
Date: Wed, 7 Jan 2004 16:08:51 -0800 [thread overview]
Message-ID: <20040108000850.GA339772@sgi.com> (raw)
In-Reply-To: <20040107232754.GA2807@kroah.com>
On Wed, Jan 07, 2004 at 03:27:54PM -0800, Greg KH wrote:
> On Wed, Jan 07, 2004 at 03:07:12PM -0800, Jesse Barnes wrote:
> >
> > 1) add pcix_enable_relaxed() and read_relaxed() (read() would always be
> > ordered)
>
> This probably preserves the current situation best, enabling driver
> writers to be explicit in knowing what is happening.
>
> thanks,
>
> greg k-h
I like this best too. That way, a driver can enable a relaxed read
in the performance path and not have to audit the other reads.
So in a generic PCI driver, you'd call pcix_enable_relaxed() and
then use read() for initialization, error recovery, etc., and
use read_relaxed() in the main execution path where it is determined
to be safe.
The default would be the standard behavior that we have.
One question I have is what the need for pcix_enable_relaxed() is.
Are we thinking that this sets some bit in one or more registers?
What happens if you use read_relaxed() and you didn't call
pcix_enable_relaxed() previously?
jeremy
next prev parent reply other threads:[~2004-01-08 0:09 UTC|newest]
Thread overview: 25+ messages / expand[flat|nested] mbox.gz Atom feed top
2004-01-07 17:58 [RFC] Relaxed PIO read vs. DMA write ordering Jesse Barnes
2004-01-07 19:02 ` Matthew Wilcox
2004-01-07 22:21 ` Grant Grundler
2004-01-07 23:07 ` Jesse Barnes
2004-01-07 23:27 ` Greg KH
2004-01-07 23:56 ` Jesse Barnes
2004-01-08 0:34 ` Jesse Barnes
2004-01-08 0:08 ` Jeremy Higdon [this message]
2004-01-08 10:01 ` Jes Sorensen
2004-01-08 6:38 ` Grant Grundler
2004-01-08 16:23 ` Leonid Grossman
2004-01-08 17:39 ` Jesse Barnes
2004-01-08 17:54 ` Christoph Hellwig
2004-01-08 19:48 ` Leonid Grossman
2004-01-08 17:36 ` Jesse Barnes
2004-01-08 18:44 ` Grant Grundler
2004-01-09 7:13 ` Jeremy Higdon
2004-01-09 19:51 ` Jesse Barnes
2004-01-09 23:15 ` Jesse Barnes
2004-01-09 20:02 ` Grant Grundler
2004-01-11 14:34 ` James Bottomley
2004-01-09 7:39 ` Jochen Friedrich
2004-01-09 20:27 ` Grant Grundler
2004-01-09 22:12 ` Ivan Kokshaysky
2004-01-07 22:58 ` Jesse Barnes
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