From 1ca36d4cb3436bd783f8688b563830341a8d9150 Mon Sep 17 00:00:00 2001 From: Paulo Zanoni Date: Wed, 23 Sep 2015 12:52:22 -0300 Subject: [PATCH] drm/i915: don't use the first stolen page on Broadwell The spec says we just can't use it. v2: - Add WA name (Ville). - Add a big comment explaining that we still didn't fix the problem where we inherit a framebuffer on the first page (Chris, Ville). Signed-off-by: Paulo Zanoni Acked-by: Chris Wilson Signed-off-by: Daniel Vetter --- drivers/gpu/drm/i915/i915_gem_stolen.c | 17 ++++++++++++++++- 1 file changed, 16 insertions(+), 1 deletion(-) diff --git a/drivers/gpu/drm/i915/i915_gem_stolen.c b/drivers/gpu/drm/i915/i915_gem_stolen.c index 15207796e1b3..69eebc678f01 100644 --- a/drivers/gpu/drm/i915/i915_gem_stolen.c +++ b/drivers/gpu/drm/i915/i915_gem_stolen.c @@ -51,6 +51,11 @@ 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,chv (incomplete) */ + if (INTEL_INFO(dev_priv)->gen == 8 && start < 4096) + 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, @@ -393,7 +398,17 @@ int i915_gem_init_stolen(struct drm_device *dev) dev_priv->gtt.stolen_usable_size = dev_priv->gtt.stolen_size - reserved_total; - /* Basic memrange allocator for stolen space */ + /* + * 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, dev_priv->gtt.stolen_usable_size); return 0; -- 2.39.5