It appears that Ironlake is very sensitive to having its GGTT PTE
updates flushed in a timely manner and requires UC rather than WC for
all, and not just under VT'd.
Signed-off-by: Chris Wilson <ch...@chris-wilson.co.uk>
---
drivers/char/agp/intel-gtt.c | 25 +------------------------
1 file changed, 1 insertion(+), 24 deletions(-)
diff --git a/drivers/char/agp/intel-gtt.c b/drivers/char/agp/intel-gtt.c
index 66a62d17a3f5..afe5e81bafac 100644
--- a/drivers/char/agp/intel-gtt.c
+++ b/drivers/char/agp/intel-gtt.c
@@ -565,35 +565,12 @@ static void intel_gtt_cleanup(void)
intel_gtt_teardown_scratch_page();
}
-/* Certain Gen5 chipsets require require idling the GPU before
- * unmapping anything from the GTT when VT-d is enabled.
- */
-static inline int needs_ilk_vtd_wa(void)
-{
-#ifdef CONFIG_INTEL_IOMMU
- const unsigned short gpu_devid = intel_private.pcidev->device;
-
- /* Query intel_iommu to see if we need the workaround. Presumably that
- * was loaded first.
- */
- if ((gpu_devid == PCI_DEVICE_ID_INTEL_IRONLAKE_D_IG ||
- gpu_devid == PCI_DEVICE_ID_INTEL_IRONLAKE_M_IG) &&
- intel_iommu_gfx_mapped)
- return 1;
-#endif
- return 0;
-}
-
static bool intel_gtt_can_wc(void)
{
if (INTEL_GTT_GEN <= 2)
return false;
- if (INTEL_GTT_GEN >= 6)
- return false;
-
- /* Reports of major corruption with ILK vt'd enabled */
- if (needs_ilk_vtd_wa())
+ if (INTEL_GTT_GEN >= 5)
return false;
return true;
--
2.20.1
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