[Bug 40103] Striped screen with CAICOS chip (1002:6779)

[bugzilla-daemon at freedesktop.org]

https://bugs.freedesktop.org/show_bug.cgi?id=40103

--- Comment #7 from Patrik Kullman <patrik at yes.nu> 2011-09-07 05:21:25 PDT ---
Created an attachment (id=50959)
 --> (https://bugs.freedesktop.org/attachment.cgi?id=50959)
dmesg with ttm dma pool 1.7 patchset

After discussion with Dave Airlie he concluded that the chipset (Intel G31 in
my case) doesn't have DMAR / IOMMU and that systems with 4GB or more memory
enabled SWIOTLB in those cases, which was the problem.

However, booting with mem=3G or with physical memory below 4GB did not solve
the problem.

Disabling iommu with iommu=off only disabled the SATA-support without solving
the Radeon-issue.

Booting with less than 4GB of memory and iommu=off did not disable SATA-support
but did not solve the issue either.

I finally tried compiling the Oneiric kernel with the TTM DMA Pool 1.7 patchset
from Konrad for Xen, but the ring test still failed. Reading the source I can
conclude that the test writes "0xDEADBEEF" but reads "0xCAFEDEAD".

Not sure how to proceed.

Attaching dmesg from boot with TTM DMA Pool 1.7 patchset.

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