From: Dan Malek <dan@embeddededge.com>
To: Eugene Surovegin <ebs@ebshome.net>
Cc: John Whitney <jwhitney-linuxppc@sands-edge.com>,
Matt Porter <mporter@kernel.crashing.org>,
linuxppc-dev@lists.linuxppc.org
Subject: Re: Problems with dma_alloc_coherent()
Date: Thu, 01 Apr 2004 13:55:10 -0500 [thread overview]
Message-ID: <406C658E.10500@embeddededge.com> (raw)
In-Reply-To: 20040401181926.GA3630@gate.ebshome.net
Eugene Surovegin wrote:
> Hmm, I don't understand this, bus != PCI bus.
Isn't that necessary due to bridge windows? If != PCI bus I guess we
assume OCP that are connected to a 1:1 mapped internal bus, which
may not be a valid assumption either.
> Current implementation just relies on the fact that PCI devices view system
> memory the same way as other-bus devices (e.g. OCP devices which sit on OPB).
I don't think so. PCI devices are known to go through bridges, while
others are assumed to not.
> In more general case, yes, "views" can be different for each bus type or even
> for each bus...
So, we should always have some kind of 'bus type' device handle, that provides
this information. It's clear that all Linux APIs are designed from the
viewpoint of PC-like workstations. They have always fallen very short when
pressed into the more prevalent embedded computing space :-)
-- Dan
** Sent via the linuxppc-dev mail list. See http://lists.linuxppc.org/
next prev parent reply other threads:[~2004-04-01 18:55 UTC|newest]
Thread overview: 36+ messages / expand[flat|nested] mbox.gz Atom feed top
2004-04-01 15:59 Problems with dma_alloc_coherent() John Whitney
2004-04-01 16:30 ` John Whitney
2004-04-01 16:51 ` Dan Malek
2004-04-01 17:01 ` Tom Rini
2004-04-01 17:05 ` Matt Porter
2004-04-01 17:51 ` John Whitney
2004-04-01 18:16 ` Matt Porter
2004-04-01 18:19 ` Eugene Surovegin
2004-04-01 18:33 ` Eugene Surovegin
2004-04-01 18:33 ` John Whitney
2004-04-01 18:40 ` Eugene Surovegin
2004-04-01 18:48 ` John Whitney
2004-04-01 18:55 ` Dan Malek [this message]
2004-04-01 18:59 ` Eugene Surovegin
2004-04-01 19:10 ` John Whitney
2004-04-01 19:17 ` Eugene Surovegin
2004-04-01 19:35 ` John Whitney
2004-04-01 20:52 ` Michael R. Zucca
2004-04-01 22:00 ` Eugene Surovegin
2004-04-01 22:39 ` Michael R. Zucca
2004-04-02 16:50 ` John Whitney
2004-04-02 18:50 ` Michael R. Zucca
2004-04-02 19:27 ` John Whitney
2004-04-02 20:20 ` Michael R. Zucca
2004-04-02 21:01 ` John Whitney
2004-04-03 7:54 ` Adrian Cox
2004-04-03 12:43 ` John Whitney
2004-04-05 9:05 ` Adrian Cox
2004-04-03 17:33 ` Brad Boyer
2004-04-03 23:17 ` Paul Mackerras
2004-04-04 8:15 ` Adrian Cox
2004-04-02 22:54 ` Paul Mackerras
2004-04-03 7:33 ` Adrian Cox
2004-04-04 22:56 ` Benjamin Herrenschmidt
2004-04-02 5:45 ` Christoph Hellwig
2004-04-01 20:49 ` Matt Porter
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