From: Heiko =?ISO-8859-1?Q?St=FCbner?= <heiko@sntech.de>
To: Joerg Roedel <joro@8bytes.org>
Cc: djkurtz@chromium.org, Tomasz Figa <tfiga@chromium.org>,
        iommu@lists.linux-foundation.org, Will Deacon <will.deacon@arm.com>,
        Kukjin Kim <kgene@kernel.org>, David Woodhouse <dwmw2@infradead.org>,
        Hiroshi Doyu <hdoyu@nvidia.com>,
        Thierry Reding <thierry.reding@gmail.com>,
        Alex Williamson <alex.williamson@redhat.com>,
        Robin Murphy <robin.murphy@arm.com>,
        Laurent Pinchart <laurent.pinchart@ideasonboard.com>,
        Oded Gabbay <oded.gabbay@gmail.com>, jroedel@suse.de,
        linux-kernel@vger.kernel.org
Subject: Re: [PATCH 03/22] iommu: Propagate error in add_iommu_group
Date: Mon, 29 Jun 2015 21:55:28 +0200
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Hi Joerg,

Am Montag, 29. Juni 2015, 16:06:37 schrieb Joerg Roedel:
> On Mon, Jun 29, 2015 at 11:28:40AM +0200, Heiko St?bner wrote:
> > The Rockchip iommu uses bus_set_ops to set its iommu-ops for the platform
> > bus and currently returns -ENODEV if it encounters a platform_devices that
> > does not have an iommu. As add_iommu_group ignored these returns
> > till now this worked, but of course starts to fail now.
> > 
> > All two invocations of the add_device callback ignored (or still ignore)
> > the return value so I've come with the following small patch to fix the
> > breakage that now exists in the 4.2 tree.
> > 
> > There is probably a better solution possible in the longer term, likely
> > similar to what Samsung does, but I'm not sure yet how this would work
> > with our drm device that needs an iommu mapping without having an
> > iommu (the iommus being attached to the crtc-components).
> 
> Btw, if you want to test the fix too, here is the link:
> 
> 	http://lists.linuxfoundation.org/pipermail/iommu/2015-June/013508.html

yep, works like a charm and fixes the issue. So if helpful:
Tested-by: Heiko Stuebner <heiko@sntech.de>


Thanks
Heiko
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