From 227213438aff3050f2dd2be92dc48c8370d445a2 Mon Sep 17 00:00:00 2001 From: Chris Wilson Date: Tue, 4 Mar 2014 09:41:43 +0000 Subject: [PATCH] Revert "drm/i915: enable HiZ Raw Stall Optimization on IVB" MIME-Version: 1.0 Content-Type: text/plain; charset=utf8 Content-Transfer-Encoding: 8bit This reverts commit 116f2b6da868dec7539103574d0421cd6221e931. This optimization causes widespread corruption in games, and even in glxgears, on my ivb:gt1. The corruption appears like z-fighting of overlapping polygons in the HiZ buffer. The observation ties in very closely with the description of the optimization disabled by default on IVB: "The Hierarchical Z RAW Stall Optimization allows non-overlapping polygons in the same 8x4 pixel/sample area to be processed without stalling waiting for the earlier ones to write to Hierarchical Z buffer." No reason is given for why it is disabled by default, usually for such optimizations it is that it is incomplete. However, there is no indication whether this a gt1 only issue either. Before considering reenabling this optimization, I would first suggest reproducing the corruption in piglit. Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=75623 Signed-off-by: Chris Wilson Cc: Chia-I Wu Cc: Ville Syrjälä Signed-off-by: Daniel Vetter --- drivers/gpu/drm/i915/intel_pm.c | 8 +++++--- 1 file changed, 5 insertions(+), 3 deletions(-) diff --git a/drivers/gpu/drm/i915/intel_pm.c b/drivers/gpu/drm/i915/intel_pm.c index d668866ba2eb..76d0bbcbeab0 100644 --- a/drivers/gpu/drm/i915/intel_pm.c +++ b/drivers/gpu/drm/i915/intel_pm.c @@ -4972,9 +4972,11 @@ static void ivybridge_init_clock_gating(struct drm_device *dev) gen7_setup_fixed_func_scheduler(dev_priv); - /* enable HiZ Raw Stall Optimization */ - I915_WRITE(CACHE_MODE_0_GEN7, - _MASKED_BIT_DISABLE(HIZ_RAW_STALL_OPT_DISABLE)); + if (0) { /* causes HiZ corruption on ivb:gt1 */ + /* enable HiZ Raw Stall Optimization */ + I915_WRITE(CACHE_MODE_0_GEN7, + _MASKED_BIT_DISABLE(HIZ_RAW_STALL_OPT_DISABLE)); + } /* WaDisable4x2SubspanOptimization:ivb */ I915_WRITE(CACHE_MODE_1, -- 2.30.2