From mboxrd@z Thu Jan  1 00:00:00 1970
From: arnd@arndb.de (Arnd Bergmann)
Date: Mon, 01 Sep 2014 13:56:42 +0200
Subject: [PATCH 10/29] drivers: add DRIVER_HAS_OWN_IOMMU_MANAGER flag
In-Reply-To: <54044EAC.6010701@samsung.com>
References: <1407235677-26324-1-git-send-email-m.szyprowski@samsung.com>
 <4621634.jlJLccozTJ@wuerfel> <54044EAC.6010701@samsung.com>
Message-ID: <5493968.dbuSPSqts4@wuerfel>
To: linux-arm-kernel@lists.infradead.org
List-Id: linux-arm-kernel.lists.infradead.org

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