We had a report of slow graphics performance in Linux 3.2 and 3.7,
apparently related to carrying out frequent IOTLB syncs.
If I understand correctly, IOTLB and GTT changes must be serialised on
Ironlake chips to avoid hangs (or access to the wrong memory address?).
These commits seem to implement the workaround:
commit 6fbcfb3e467adb414e235eeefaeaf51ad12f2461
Author: David Woodhouse <dwmw2@infradead.org>
Date: Sun Sep 25 19:11:14 2011 -0700
intel-iommu: Workaround IOTLB hang on Ironlake GPU
commit 5c0422878fcdc279ae9a8e8b66972a15b5efb67f
Author: Ben Widawsky <ben@bwidawsk.net>
Date: Mon Oct 17 15:51:55 2011 -0700
drm/i915: ILK + VT-d workaround
The intel-iommu quirk is applied if any of these device IDs are found:
#define PCI_DEVICE_ID_INTEL_IRONLAKE_D_HB 0x0040
#define PCI_DEVICE_ID_INTEL_IRONLAKE_M_HB 0x0044
#define PCI_DEVICE_ID_INTEL_IRONLAKE_MA_HB 0x0062
#define PCI_DEVICE_ID_INTEL_IRONLAKE_MC2_HB 0x006a
though not:
#define PCI_DEVICE_ID_INTEL_IRONLAKE_D2_HB 0x0069
The intel-gtt quirk is applied if either of these are found as the IGP:
#define PCI_DEVICE_ID_INTEL_IRONLAKE_M_HB 0x0044
#define PCI_DEVICE_ID_INTEL_IRONLAKE_M_IG 0x0046
but of course the first will never match.
Does the bug affect Ironlake D or not?
Ben.
--
Ben Hutchings
Absolutum obsoletum. (If it works, it's out of date.) - Stafford Beer
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