linux-kernel - Re: [Intel-gfx] [PATCH] iommu: export no_iommu and dmar

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Message-ID: <1322080560.15493.206.camel@shinybook.infradead.org>
Date:	Wed, 23 Nov 2011 20:36:00 +0000
From:	David Woodhouse <dwmw2@...radead.org>
To:	Eugeni Dodonov <eugeni.dodonov@...el.com>
Cc:	intel-gfx@...ts.freedesktop.org,
	Daniel Vetter <daniel.vetter@...ll.ch>,
	linux-kernel@...r.kernel.org, dri-devel@...ts.freedesktop.org
Subject: Re: [Intel-gfx] [PATCH] iommu: export no_iommu and dmar_disabled
 symbols

On Wed, 2011-11-23 at 16:42 -0200, Eugeni Dodonov wrote:
> Those are needed by the rc6 and semaphores support in i915 driver.
> 
> In i915 driver, we do not enable either rc6 or semaphores on SNB when dmar
> is enabled. So we use those variables to check the io remapping and iommu
> status.

This is horrid. In the general case, drivers have no business knowing
this. We need to properly identify what is wrong with this hardware, and
put in a quirk for it — perhaps refusing to enable the IOMMU at all on
the broken chipsets.

-- 
dwmw2

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