From: arnd@arndb•de (Arnd Bergmann)
To: linux-arm-kernel@lists•infradead.org
Subject: [RFC][PATCH] devicetree: Add master-id-bits property to the iommu device
Date: Mon, 15 Sep 2014 04:38:29 +0200 [thread overview]
Message-ID: <201409150438.29649.arnd@arndb.de> (raw)
In-Reply-To: <1410718646-9710-1-git-send-email-Varun.Sethi@freescale.com>
On Sunday 14 September 2014, Varun Sethi wrote:
> "master-id-bits" property added to the IOMMU device node. This property can
> be used by the IOMMU driver to match relevan bits in the master id expressed
> by a DMA master.
>
> This can be used to mask out certain bits that get added to the device master id
> due to IOMMU topology. For example, in case of MMU-500 the TBUID gets appended to
> the master id. This prevents sharing of a stream ID, amongst devices which are
> connected to different TBUs.
>
> Signed-off-by: Varun Sethi <Varun.Sethi@freescale•com>
This seems rather specific to MMU-500. I don't think that most IOMMUs would
use the term 'master ID', 'stream ID' or even the general concept, and you don't
expand the acronym 'TBU'. I've seen many IOMMUs and I don't even know what
that means.
Why do you think this is something that is needed to be known at the global
level, rather than a property for some individual drivers?
Arnd
next prev parent reply other threads:[~2014-09-15 2:38 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-09-14 18:17 [RFC][PATCH] devicetree: Add master-id-bits property to the iommu device Varun Sethi
2014-09-15 2:38 ` Arnd Bergmann [this message]
2014-09-15 10:37 ` Varun Sethi
2014-09-15 16:57 ` Arnd Bergmann
2014-09-16 18:04 ` Varun Sethi
2014-09-22 9:23 ` Thierry Reding
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