From: James Bottomley <James.Bottomley@steeleye.com>
To: Jeremy Higdon <jeremy@sgi.com>
Cc: Jesse Barnes <jbarnes@engr.sgi.com>, linux-arch@vger.kernel.org
Subject: Re: [PATCH] I/O space write barrier
Date: 23 Sep 2004 19:36:52 -0400 [thread overview]
Message-ID: <1095982621.1572.4.camel@mulgrave> (raw)
In-Reply-To: <20040923222250.GB157288@sgi.com>
On Thu, 2004-09-23 at 18:22, Jeremy Higdon wrote:
> James, is this what you want?
> I think these are the only writes that need ordering, as opposed to flushing.
> Being not certain what was intended in the other cases, it's safer to leave
> them be.
Well, these two are just the kicks to tell the card that we have filled
a consistent memory slot with a SCSI command. The ordering, I assume,
is because we want SCSI commands issued in the order they went down to
queuecommand in, so the mmiowb() preserves that order? Could we have a
comment to that effect.
My objection isn't so much that what the original patch did would result
in errors, merely that we have enough trouble explaining these issues to
device driver writers, so whatever you do in your patches demonstrating
use has to be really exemplary.
James
next prev parent reply other threads:[~2004-09-23 23:37 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
2004-09-23 18:48 [PATCH] I/O space write barrier Jesse Barnes
2004-09-23 19:03 ` James Bottomley
2004-09-23 19:07 ` Jesse Barnes
2004-09-23 19:27 ` James Bottomley
2004-09-23 19:41 ` Jesse Barnes
2004-09-23 19:57 ` Jeremy Higdon
2004-09-23 22:22 ` Jeremy Higdon
2004-09-23 23:36 ` James Bottomley [this message]
2004-09-24 5:03 ` Jeremy Higdon
2004-09-23 19:55 ` Jeremy Higdon
2004-09-23 20:09 ` Jesse Barnes
2004-09-27 0:45 ` Benjamin Herrenschmidt
2004-09-27 15:41 ` Jesse Barnes
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