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Message-ID: <5493968.dbuSPSqts4@wuerfel>
Date: Mon, 01 Sep 2014 13:56:42 +0200
From: Arnd Bergmann <arnd@...db.de>
To: Marek Szyprowski <m.szyprowski@...sung.com>
Cc: linux-arm-kernel@...ts.infradead.org,
Thierry Reding <treding@...dia.com>,
Rob Herring <robh@...nel.org>,
"linux-samsung-soc@...r.kernel.org"
<linux-samsung-soc@...r.kernel.org>,
Shaik Ameer Basha <shaik.ameer@...sung.com>,
Inki Dae <inki.dae@...sung.com>,
Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
Joerg Roedel <joro@...tes.org>,
"Rafael J. Wysocki" <rjw@...ysocki.net>,
"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
Tomasz Figa <tomasz.figa@...il.com>,
"linaro-mm-sig@...ts.linaro.org" <linaro-mm-sig@...ts.linaro.org>,
"iommu@...ts.linux-foundation.org" <iommu@...ts.linux-foundation.org>,
Kukjin Kim <kgene.kim@...sung.com>,
Laurent Pinchart <laurent.pinchart@...asonboard.com>,
Sylwester Nawrocki <s.nawrocki@...sung.com>,
Olof Johansson <olof@...om.net>,
Kyungmin Park <kyungmin.park@...sung.com>,
Cho KyongHo <pullip.cho@...sung.com>
Subject: Re: [PATCH 10/29] drivers: add DRIVER_HAS_OWN_IOMMU_MANAGER flag
On Monday 01 September 2014 12:47:08 Marek Szyprowski wrote:
> > Who do you think needs to set this flag, and who needs to read it?
>
> In the proposed solution Exynos IOMMU driver creates a separate IO
> address space
> for every client device in a system and binds it to the default
> dma-mapping space
> for the given device. When drivers are doing its own management of IO
> address
> space, instead of relying on what is available by default with dma-mapping
> interface, this will require releasing of the previously created default
> structures and resources. So this flag is set by the driver doing its own
> management of io address space. The flags is then checked by Exynos
> IOMMU driver
> to avoid creating the default dma-mapping address space for devices
> which driver
> does its own management.
I don't completely understand it yet. I would assume the device
to be added to the default domain at device creation time
(of_platform_populate), way before we know which device driver
is going to be used. How can this prevent the iommu driver
from doing the association with the domain?
Arnd
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