On Wed, Dec 14, 2016 at 12:55:38PM -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. But the BIOS should not be > putting it at the start of stolen since it's going to get corrupted. I > suppose the bug here is that some pixels at the very top of the screen > will be corrupted, so it's not exactly easy to notice. > > We have confirmation that the first page of stolen does actually get > corrupted, so I really think we should do this in order to avoid any > possible future headaches, even if that means losing BIOS framebuffer > inheritance. Let's not use the HW in a way it's not supposed to be > used. > > v2: don't even put the first page on the mm (Chris). > > Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=94605 > Cc: Chris Wilson <chris@xxxxxxxxxxxxxxxxxx> > Signed-off-by: Paulo Zanoni <paulo.r.zanoni@xxxxxxxxx> > --- > drivers/gpu/drm/i915/i915_gem_stolen.c | 27 ++++++++------------------- > 1 file changed, 8 insertions(+), 19 deletions(-) > > diff --git a/drivers/gpu/drm/i915/i915_gem_stolen.c b/drivers/gpu/drm/i915/i915_gem_stolen.c > index b1c8897..7435540 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, > @@ -410,7 +404,7 @@ int i915_gem_init_stolen(struct drm_i915_private *dev_priv) > { > struct i915_ggtt *ggtt = &dev_priv->ggtt; > unsigned long reserved_total, reserved_base = 0, reserved_size; > - unsigned long stolen_top; > + unsigned long stolen_start = 0, stolen_top; > > mutex_init(&dev_priv->mm.stolen_lock); > > @@ -491,18 +485,13 @@ 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. > - */ > - drm_mm_init(&dev_priv->mm.stolen, 0, ggtt->stolen_usable_size); > + /* WaSkipStolenMemoryFirstPage:bdw+ */ > + if (INTEL_GEN(dev_priv) >= 8) > + stolen_start = 4096; > + > + /* Basic memrange allocator for stolen space. */ > + drm_mm_init(&dev_priv->mm.stolen, stolen_start, > + ggtt->stolen_usable_size); Don't you need to reduce the size by 4k as well? -- Ville Syrjälä Intel OTC _______________________________________________ Intel-gfx mailing list Intel-gfx@xxxxxxxxxxxxxxxxxxxxx https://lists.freedesktop.org/mailman/listinfo/intel-gfx
