Re: 2.6.28-rc1: [drm:i915] *ERROR* ... Disabling tiling

From: Alan Jenkins
Date: Mon Mar 23 2009 - 05:50:43 EST


On 10/27/08, Eric Anholt <eric@xxxxxxxxxx> wrote:
> On Mon, 2008-10-27 at 14:27 +0000, Alan Jenkins wrote:
>> What does this mean, should I do anything about it? Is tiling nice to
>> have?
>>
>> It sounds like GEM broke something - though maybe it just added a more
>> verbose error report.
>>
>> System: EeePC 701
>> Kernel: v2.6.28-rc1-5-g23cf24c
>> Chipset: Intel mobile 915G-something
>> Regretably necessary kernel boot option: noapic
>>
>>
>> [ 1.438441] Linux agpgart interface v0.103
>> [ 1.438441] agpgart-intel 0000:00:00.0: Intel 915GM Chipset
>> [ 1.438441] agpgart-intel 0000:00:00.0: detected 7932K stolen memory
>> [ 1.443353] agpgart-intel 0000:00:00.0: AGP aperture is 256M @
>> 0xd0000000
>> [ 1.443353] [drm] Initialized drm 1.1.0 20060810
>> [ 1.443353] pci 0000:00:02.0: PCI INT A -> Link[LNKA] -> GSI 5
>> (level, low) -> IRQ 5
>> [ 1.443353] pci 0000:00:02.0: setting latency timer to 64
>> [ 1.443353] [drm:i915_gem_detect_bit_6_swizzle] *ERROR* Couldn't read
>> from MCHBAR. Disabling
>> tiling.
>
> This means that something went wrong with our detection of the
> CPU-versus-GPU tiling swizzling mode, and object tiling under GEM will
> be disabled as a result. I should get access to an eee 7xx on Thursday
> to see what's up with it -- it's supposed to be just a normal 915gm as
> far as I know.

Any news about this tiling error?

It's already been reported as a bug in Ubuntu Jaunty, in the belief
that it "reduces video performance" [1], and is also mentioned on a
similar bug in Fedora [2].

[1] <https://bugzilla.redhat.com/show_bug.cgi?id=444328#c37>
[2] <https://bugs.launchpad.net/ubuntu/+source/xserver-xorg-video-intel/+bug/329266>

Thanks
Alan
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