linux-kernel - Re: [PATCH] iommu/intel: quirk to disable DMAR for QM57 igfx

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Message-ID: <20190122165135.6rkdsxqepvmaoatn@8bytes.org>
Date:   Tue, 22 Jan 2019 17:51:35 +0100
From:   Joerg Roedel <joro@...tes.org>
To:     Joonas Lahtinen <joonas.lahtinen@...ux.intel.com>
Cc:     Daniel Vetter <daniel@...ll.ch>, Eric Wong <e@...24.org>,
        David Woodhouse <dwmw2@...radead.org>,
        David Airlie <airlied@...ux.ie>,
        Jani Nikula <jani.nikula@...ux.intel.com>,
        Rodrigo Vivi <rodrigo.vivi@...el.com>,
        "list@....net:IOMMU DRIVERS <iommu@...ts.linux-foundation.org>, Joerg
        Roedel <joro@...tes.org>, " <iommu@...ts.linux-foundation.org>,
        intel-gfx <intel-gfx@...ts.freedesktop.org>,
        dri-devel <dri-devel@...ts.freedesktop.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] iommu/intel: quirk to disable DMAR for QM57 igfx

On Tue, Jan 22, 2019 at 04:48:26PM +0200, Joonas Lahtinen wrote:
> According to our IOMMU folks there exists some desire to be able to assign
> the iGFX device aka have intel_iommu=on instead of intel_iommu=igfx_off
> due to how the devices might be grouped in IOMMU groups. Even when you
> would not be using the iGFX device.

You can force the igfx device into a SI domain, or does that also
trigger the iommu issues on the chipset?

In any case, if iommu=on breaks these systems I want to make them work
again with opt-out, even at the cost of breaking assignability.

Regards,

	Joerg