Date: Mon, 29 Jun 2015 11:37:03 +0200
From: Joerg Roedel <jroedel@suse.de>
To: Heiko =?iso-8859-1?Q?St=FCbner?= <heiko@sntech.de>
Cc: Joerg Roedel <joro@8bytes.org>, 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>, linux-kernel@vger.kernel.org
Subject: Re: [PATCH 03/22] iommu: Propagate error in add_iommu_group
Message-ID: <20150629093703.GA16648@suse.de>
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Hello Heiko,

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).

Yes, this issue was already reported from the Exynos side. I have a fix
which just ignores -ENODEV as the return value for now. This fixes
Exynos, and should fix Rockchip (and some other IOMMU drivers) too.


	Joerg

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