From 6ba0566cf2afcdb17bff882e3a95cbbcb22c4a83 Mon Sep 17 00:00:00 2001 From: Paulo Zanoni Date: Wed, 14 Dec 2016 12:55:37 -0200 Subject: [PATCH] drm/i915: skip the first 4k of stolen memory on everything >= gen8 BSpec got updated and this workaround is now listed as standard required programming for all subsequent projects. This is confirmed to fix Skylake screen flickering issues (probably caused by the fact that we initialized a ring in the first page of stolen, but I didn't 100% confirm this theory). v2: this is the patch that fixes the screen flickering, document it. Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=94605 Cc: stable@vger.kernel.org Tested-by: Dominik Klementowski Signed-off-by: Paulo Zanoni Acked-by: Chris Wilson Reviewed-by: Daniel Vetter Link: http://patchwork.freedesktop.org/patch/msgid/1481727338-9901-1-git-send-email-paulo.r.zanoni@intel.com (cherry picked from commit d43537610470d8829ebd17cd7842f47176e35ebd) Signed-off-by: Jani Nikula --- drivers/gpu/drm/i915/i915_gem_stolen.c | 5 ++--- 1 file changed, 2 insertions(+), 3 deletions(-) diff --git a/drivers/gpu/drm/i915/i915_gem_stolen.c b/drivers/gpu/drm/i915/i915_gem_stolen.c index ebaa941..abc78bb 100644 --- a/drivers/gpu/drm/i915/i915_gem_stolen.c +++ b/drivers/gpu/drm/i915/i915_gem_stolen.c @@ -55,10 +55,9 @@ int i915_gem_stolen_insert_node_in_range(struct drm_i915_private *dev_priv, return -ENODEV; /* See the comment at the drm_mm_init() call for more about this check. - * WaSkipStolenMemoryFirstPage:bdw,chv,kbl (incomplete) + * WaSkipStolenMemoryFirstPage:bdw+ (incomplete) */ - if (start < 4096 && (IS_GEN8(dev_priv) || - IS_KBL_REVID(dev_priv, 0, KBL_REVID_A0))) + if (start < 4096 && INTEL_GEN(dev_priv) >= 8) start = 4096; mutex_lock(&dev_priv->mm.stolen_lock); -- 2.7.4