diff options
authorDavid Woodhouse <>2015-01-20 17:21:42 +0000
committerJani Nikula <>2015-01-21 18:13:27 +0200
commit65997b08c61175a4fd68af8eea0308fb77b90108 (patch)
parent226e5ae9e5f9108beb0bde4ac69f68fe6210fed9 (diff)
drm/i915: Init PPGTT before context enable
Commit 82460d972 ("drm/i915: Rework ppgtt init to no require an aliasing ppgtt") introduced a regression on Broadwell, triggering the following IOMMU fault at startup: vgaarb: device changed decodes: PCI:0000:00:02.0,olddecodes=io+mem,decodes=io+mem:owns=io+mem dmar: DRHD: handling fault status reg 2 dmar: DMAR:[DMA Write] Request device [00:02.0] fault addr 880000 DMAR:[fault reason 23] Unknown fbcon: inteldrmfb (fb0) is primary device Further commentary from Daniel: I sugggested this change to David after staring at the offending patch for a while. I have no idea and theory whatsoever why this would upset the gpu less than the other way round. But it seems to work. David promised to chase hw people a bit more to get a more meaningful answer. Wrt the comment that this deletes: I've done some digging and afaict loading context before ppgtt enable was once required before our recent restructuring of the context/ppgtt init code: Before that context sw setup (i.e. allocating the default context) and hw setup was smashed together. Also the setup of the default context was the bit that actually allocated the aliasing ppgtt structures. Which is the reason for the context before ppgtt depency. Or was, since with all the untangling there's no no real depency any more (functional, who knows what the hw is doing), so the comment is just stale. Signed-off-by: David Woodhouse <> Cc: Reviewed-by: Daniel Vetter <> Signed-off-by: Jani Nikula <>
1 files changed, 6 insertions, 13 deletions
diff --git a/drivers/gpu/drm/i915/i915_gem.c b/drivers/gpu/drm/i915/i915_gem.c
index 76354d3ba925..b4a4f36d2f00 100644
--- a/drivers/gpu/drm/i915/i915_gem.c
+++ b/drivers/gpu/drm/i915/i915_gem.c
@@ -4884,25 +4884,18 @@ i915_gem_init_hw(struct drm_device *dev)
for (i = 0; i < NUM_L3_SLICES(dev); i++)
i915_gem_l3_remap(&dev_priv->ring[RCS], i);
- /*
- * XXX: Contexts should only be initialized once. Doing a switch to the
- * default context switch however is something we'd like to do after
- * reset or thaw (the latter may not actually be necessary for HW, but
- * goes with our code better). Context switching requires rings (for
- * the do_switch), but before enabling PPGTT. So don't move this.
- */
- ret = i915_gem_context_enable(dev_priv);
+ ret = i915_ppgtt_init_hw(dev);
if (ret && ret != -EIO) {
- DRM_ERROR("Context enable failed %d\n", ret);
+ DRM_ERROR("PPGTT enable failed %d\n", ret);
- return ret;
- ret = i915_ppgtt_init_hw(dev);
+ ret = i915_gem_context_enable(dev_priv);
if (ret && ret != -EIO) {
- DRM_ERROR("PPGTT enable failed %d\n", ret);
+ DRM_ERROR("Context enable failed %d\n", ret);
+ return ret;
return ret;