From: Roland Dreier <rdreier@cisco.com>
To: Arnd Bergmann <arnd@arndb.de>
Cc: Mark Nelson <markn@au1.ibm.com>,
linuxppc-dev@ozlabs.org, cbe-oss-dev@ozlabs.org
Subject: Re: [patch 9/9] powerpc/cell: Add DMA_ATTR_STRONG_ORDERING dma attribute and use in IOMMU code
Date: Tue, 15 Jul 2008 19:18:46 -0700 [thread overview]
Message-ID: <ada7ibmd115.fsf@cisco.com> (raw)
In-Reply-To: <200807152327.06946.arnd@arndb.de> (Arnd Bergmann's message of "Tue, 15 Jul 2008 23:27:06 +0200")
> This is all about inbound transfers, i.e. DMAs coming from the I/O bridge
> into the CPU, both DMA read and DMA write.
OK -- at a minimum I think the documentation should make that clear. As
it stands the description of what this does is pretty much impossible to
parse and understand.
> Strong ordering is only active when both the bridge and the IOMMU enable
> it, but for correctly written drivers, this only results in a slowdown.
So when would someone use this dma attribute? As a hack to fix drivers
where the real fix is too complicated?
- R.
next prev parent reply other threads:[~2008-07-16 2:18 UTC|newest]
Thread overview: 25+ messages / expand[flat|nested] mbox.gz Atom feed top
2008-07-15 19:51 [patch 0/9] Cell patches for 2.6.27, version 2 arnd
2008-07-15 19:51 ` [patch 1/9] powerpc/cell/edac: log a syndrome code in case of correctable error arnd
2008-07-17 5:59 ` Benjamin Herrenschmidt
2008-07-17 18:35 ` Doug Thompson
2008-07-15 19:51 ` [patch 2/9] powerpc/axonram: use only one block device major number arnd
2008-07-15 19:51 ` [patch 3/9] powerpc/axonram: enable partitioning of the Axons DDR2 DIMMs arnd
2008-07-15 19:51 ` [patch 4/9] powerpc/cell/cpufreq: add spu aware cpufreq governor arnd
2008-07-15 19:51 ` [patch 5/9] powerpc/cell: cleanup sysreset_hack for IBM cell blades arnd
2008-07-15 19:51 ` [patch 6/9] powerpc/cell: add support for power button of future " arnd
2008-07-15 19:51 ` [patch 7/9] azfs: initial submit of azfs, a non-buffered filesystem arnd
2008-07-17 6:13 ` Benjamin Herrenschmidt
2008-07-22 9:49 ` [Cbe-oss-dev] " Christoph Hellwig
2008-07-15 19:51 ` [patch 8/9] powerpc/dma: use the struct dma_attrs in iommu code arnd
2008-07-15 19:51 ` [patch 9/9] powerpc/cell: Add DMA_ATTR_STRONG_ORDERING dma attribute and use in IOMMU code arnd
2008-07-15 20:34 ` Roland Dreier
2008-07-15 21:27 ` Arnd Bergmann
2008-07-16 2:18 ` Roland Dreier [this message]
2008-07-16 7:54 ` Arnd Bergmann
2008-07-17 6:20 ` [Cbe-oss-dev] " Benjamin Herrenschmidt
2008-07-17 14:53 ` Arnd Bergmann
2008-07-17 20:10 ` Benjamin Herrenschmidt
2008-07-17 20:10 ` Benjamin Herrenschmidt
2008-07-18 13:03 ` [PATCH] Add DMA_ATTR_WEAK_ORDERING dma attribute and use in Cell " Arnd Bergmann
2008-07-19 7:29 ` [Cbe-oss-dev] " Jeremy Kerr
2008-07-19 8:36 ` Arnd Bergmann
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