From: Arnd Bergmann <arnd@arndb.de>
To: linux-arm-kernel@lists.infradead.org
Cc: Thierry Reding <thierry.reding@gmail.com>,
Mark Rutland <mark.rutland@arm.com>,
devicetree@vger.kernel.org, linux-samsung-soc@vger.kernel.org,
Pawel Moll <pawel.moll@arm.com>,
Ian Campbell <ijc+devicetree@hellion.org.uk>,
Grant Grundler <grundler@chromium.org>,
Joerg Roedel <joro@8bytes.org>,
Stephen Warren <swarren@wwwdotorg.org>,
Will Deacon <will.deacon@arm.com>,
linux-kernel@vger.kernel.org, Marc Zyngier <marc.zyngier@arm.com>,
iommu@lists.linux-foundation.org,
Rob Herring <robh+dt@kernel.org>,
Kumar Gala <galak@codeaurora.org>,
linux-tegra@vger.kernel.org, Cho KyongHo <pullip.cho@samsung.com>,
Dave Martin <Dave.Martin@arm.com>
Subject: Re: [PATCH] devicetree: Add generic IOMMU device tree bindings
Date: Wed, 21 May 2014 11:32:23 +0200 [thread overview]
Message-ID: <11242680.PQytQQqlPJ@wuerfel> (raw)
In-Reply-To: <20140521090244.GB19268@ulmo>
On Wednesday 21 May 2014 11:02:45 Thierry Reding wrote:
> On Wed, May 21, 2014 at 10:54:42AM +0200, Arnd Bergmann wrote:
>
> > Right. As long as we always unmap the buffers from the IOMMU after they
> > have stopped being in use, it's very unlikely that even a broken device
> > driver causes a DMA into some bus address that happens to be mapped for
> > another device.
>
> I think that if buffers remain mapped in the IOMMU when they have been
> deallocated that should be considered a bug.
You could see it as a performance optimization in some cases, e.g. when you
cannot flush individual IOTLBs or doing so is expensive, and you just keep
assigning new addresses until every one has been used, then you do a global
IOTLB flush once. Obviously you have to maintain the IO page tables correctly.
Arnd
next prev parent reply other threads:[~2014-05-21 9:32 UTC|newest]
Thread overview: 40+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-05-16 12:23 [PATCH] devicetree: Add generic IOMMU device tree bindings Thierry Reding
[not found] ` <1400242998-437-1-git-send-email-thierry.reding-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>
2014-05-17 8:04 ` Cho KyongHo
2014-05-17 20:48 ` Thierry Reding
2014-05-19 10:26 ` Arnd Bergmann
2014-05-19 12:53 ` Thierry Reding
2014-05-19 17:22 ` Dave Martin
[not found] ` <20140519172113.GA13858-M5GwZQ6tE7x5pKCnmE3YQBJ8xKzm50AiAL8bYrjMMd8@public.gmane.org>
2014-05-19 20:32 ` Thierry Reding
2014-05-20 10:08 ` Arnd Bergmann
2014-05-20 13:07 ` Dave Martin
[not found] ` <20140520130659.GA5041-M5GwZQ6tE7x5pKCnmE3YQBJ8xKzm50AiAL8bYrjMMd8@public.gmane.org>
2014-05-20 13:23 ` Arnd Bergmann
2014-05-20 15:26 ` Will Deacon
[not found] ` <20140520152659.GA30404-5wv7dgnIgG8@public.gmane.org>
2014-05-20 16:39 ` Dave Martin
[not found] ` <20140520163912.GC5041-M5GwZQ6tE7x5pKCnmE3YQBJ8xKzm50AiAL8bYrjMMd8@public.gmane.org>
2014-05-20 20:40 ` Arnd Bergmann
2014-05-19 18:34 ` Arnd Bergmann
2014-05-19 20:59 ` Thierry Reding
2014-05-20 10:04 ` Arnd Bergmann
2014-05-20 11:05 ` Thierry Reding
2014-05-20 11:15 ` Arnd Bergmann
2014-05-20 12:02 ` Thierry Reding
2014-05-20 12:41 ` Arnd Bergmann
2014-05-20 13:17 ` Thierry Reding
2014-05-20 13:34 ` Arnd Bergmann
2014-05-20 14:00 ` Thierry Reding
2014-05-20 20:31 ` Arnd Bergmann
2014-05-21 8:16 ` Thierry Reding
2014-05-21 8:54 ` Arnd Bergmann
2014-05-21 9:02 ` Thierry Reding
2014-05-21 9:32 ` Arnd Bergmann [this message]
2014-05-21 15:44 ` Grant Grundler
2014-05-21 16:01 ` Arnd Bergmann
2014-05-20 15:24 ` Dave Martin
[not found] ` <20140520152458.GB5041-M5GwZQ6tE7x5pKCnmE3YQBJ8xKzm50AiAL8bYrjMMd8@public.gmane.org>
2014-05-20 20:26 ` Arnd Bergmann
2014-05-21 8:26 ` Thierry Reding
2014-05-21 8:50 ` Arnd Bergmann
2014-05-21 9:00 ` Thierry Reding
2014-05-21 9:36 ` Arnd Bergmann
2014-05-21 10:50 ` Thierry Reding
2014-05-21 14:01 ` Arnd Bergmann
2014-05-21 17:09 ` Dave Martin
[not found] ` <20140521170954.GC3830-M5GwZQ6tE7x5pKCnmE3YQBJ8xKzm50AiAL8bYrjMMd8@public.gmane.org>
2014-05-21 18:11 ` Arnd Bergmann
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