On Tue, Dec 13, 2016 at 05:57:26PM -0200, Paulo Zanoni wrote: > Reserve the first page of stolen memory right after initializing the > mm allocator. This means that we won't inherit the FB in case the BIOS > decides to put it at the start of stolen. IMHO, avoiding constant > screen flickering is more important than BIOS framebuffer inheritance. > > TODO: the goal is to ask everybody with screen flickering problems to > test this patch. Hopefully we'll be able to add a bunch of Bugzilla > tags here before merging it. > > Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=94605 > Cc: stable@xxxxxxxxxxxxxxx > Signed-off-by: Paulo Zanoni <paulo.r.zanoni@xxxxxxxxx> > --- > drivers/gpu/drm/i915/i915_drv.h | 3 +++ > drivers/gpu/drm/i915/i915_gem_stolen.c | 30 +++++++++++++----------------- > 2 files changed, 16 insertions(+), 17 deletions(-) > > > Time to spam bugzilla again with links to patchwork. The tester on > fd.o bug 94605 suggests this may be the fix we've been looking for. > > > diff --git a/drivers/gpu/drm/i915/i915_drv.h b/drivers/gpu/drm/i915/i915_drv.h > index 0e11ed7..0868a88 100644 > --- a/drivers/gpu/drm/i915/i915_drv.h > +++ b/drivers/gpu/drm/i915/i915_drv.h > @@ -1531,6 +1531,9 @@ struct i915_gem_mm { > /** LRU list of objects with fence regs on them. */ > struct list_head fence_list; > > + /** First page of stolen, for platforms where it's reserved. */ > + struct drm_mm_node first_page; > + > /** > * Are we in a non-interruptible section of code like > * modesetting? > diff --git a/drivers/gpu/drm/i915/i915_gem_stolen.c b/drivers/gpu/drm/i915/i915_gem_stolen.c > index b1c8897..9b3ae58 100644 > --- a/drivers/gpu/drm/i915/i915_gem_stolen.c > +++ b/drivers/gpu/drm/i915/i915_gem_stolen.c > @@ -54,12 +54,6 @@ int i915_gem_stolen_insert_node_in_range(struct drm_i915_private *dev_priv, > if (!drm_mm_initialized(&dev_priv->mm.stolen)) > return -ENODEV; > > - /* See the comment at the drm_mm_init() call for more about this check. > - * WaSkipStolenMemoryFirstPage:bdw+ (incomplete) > - */ > - if (start < 4096 && INTEL_GEN(dev_priv) >= 8) > - start = 4096; > - > mutex_lock(&dev_priv->mm.stolen_lock); > ret = drm_mm_insert_node_in_range(&dev_priv->mm.stolen, node, size, > alignment, start, end, > @@ -286,6 +280,9 @@ void i915_gem_cleanup_stolen(struct drm_device *dev) > if (!drm_mm_initialized(&dev_priv->mm.stolen)) > return; > > + if (drm_mm_node_allocated(&dev_priv->mm.first_page)) > + drm_mm_remove_node(&dev_priv->mm.first_page); > + > drm_mm_takedown(&dev_priv->mm.stolen); > } > > @@ -491,19 +488,18 @@ int i915_gem_init_stolen(struct drm_i915_private *dev_priv) > > ggtt->stolen_usable_size = ggtt->stolen_size - reserved_total; > > - /* > - * Basic memrange allocator for stolen space. > - * > - * TODO: Notice that some platforms require us to not use the first page > - * of the stolen memory but their BIOSes may still put the framebuffer > - * on the first page. So we don't reserve this page for now because of > - * that. Our current solution is to just prevent new nodes from being > - * inserted on the first page - see the check we have at > - * i915_gem_stolen_insert_node_in_range(). We may want to fix the fbcon > - * problem later. > - */ > + /* Basic memrange allocator for stolen space. */ > drm_mm_init(&dev_priv->mm.stolen, 0, ggtt->stolen_usable_size); > > + /* WaSkipStolenMemoryFirstPage:bdw+ */ > + if (INTEL_GEN(dev_priv) >= 8) { > + dev_priv->mm.first_page.start = 0; > + dev_priv->mm.first_page.size = 4096; > + if (drm_mm_reserve_node(&dev_priv->mm.stolen, > + &dev_priv->mm.first_page)) > + DRM_DEBUG_KMS("Failed to reserve the first page of stolen memory.\n"); > + } If you are saying that the first page can never be used, then just don't put into the range allocator. -Chris -- Chris Wilson, Intel Open Source Technology Centre _______________________________________________ Intel-gfx mailing list Intel-gfx@xxxxxxxxxxxxxxxxxxxxx https://lists.freedesktop.org/mailman/listinfo/intel-gfx
