From: Stefan Richter <stefanr@s5r6.in-berlin.de>
To: Alan <alan@lxorguk.ukuu.org.uk>
Cc: linux1394-devel@lists.sourceforge.net, linux-kernel@vger.kernel.org
Subject: Re: [rfc PATCH] ieee1394: ohci1394: delete bogus spinlock, flush MMIO writes
Date: Wed, 29 Nov 2006 00:50:43 +0100 [thread overview]
Message-ID: <456CCB53.70208@s5r6.in-berlin.de> (raw)
In-Reply-To: <20061128215621.2e0ac9a6@localhost.localdomain>
Alan wrote:
> On Tue, 28 Nov 2006 22:24:11 +0100 (CET)
> Stefan Richter <stefanr@s5r6.in-berlin.de> wrote:
>> All MMIO writes which were surrounded by the spinlock as well as the
>> very last MMIO write of the IRQ handler are now explicitly flushed by
>> MMIO reads of the respective register.
>
> MMIO is ordered anyway on the bus, you just need mmiowb() to force
> ordering to the bus controller in case you are on a big numa box.
The mmiowb is a checkpoint to ensure ordering between different threads
of MMIO writes; i.e. it doesn't halt the thread until the write actually
reached the device like a read would do, right?
--
Stefan Richter
-=====-=-==- =-== ===-=
http://arcgraph.de/sr/
next prev parent reply other threads:[~2006-11-28 23:50 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2006-11-28 21:24 [rfc PATCH] ieee1394: ohci1394: delete bogus spinlock, flush MMIO writes Stefan Richter
2006-11-28 21:56 ` Alan
2006-11-28 23:50 ` Stefan Richter [this message]
2006-11-29 1:26 ` Alan
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