| Message ID | 1393926103-26096-1-git-send-email-chris@chris-wilson.co.uk (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
On Tue, Mar 4, 2014 at 5:41 PM, Chris Wilson <chris@chris-wilson.co.uk> wrote: > 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. I wonder if Haswell GT1 is affected too (that's in another commit). I do not own a GT1 for either GEN to verify the issue or to create a sensible piglit test. > > Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=75623 > Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk> > Cc: Chia-I Wu <olv@lunarg.com> > Cc: Ville Syrjälä <ville.syrjala@linux.intel.com> > --- > 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 b016d9bcd7c1..6b4d1a89e9bc 100644 > --- a/drivers/gpu/drm/i915/intel_pm.c > +++ b/drivers/gpu/drm/i915/intel_pm.c > @@ -4908,9 +4908,11 @@ 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, > -- > 1.9.0 >
On Tue, Mar 04, 2014 at 10:38:58PM +0800, Chia-I Wu wrote: > On Tue, Mar 4, 2014 at 5:41 PM, Chris Wilson <chris@chris-wilson.co.uk> wrote: > > 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. > I wonder if Haswell GT1 is affected too (that's in another commit). I > do not own a GT1 for either GEN to verify the issue or to create a > sensible piglit test. I'm seeing corruption on IVB GT2 as well. I might be more blind than Chris or it's less subtle on GT2 since it took me a while to spot it. Seems to be easiest to spot in Epic citadel when you go inside the temple. I can't spot the same corruption on HSW GT3. > > > > > Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=75623 > > Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk> > > Cc: Chia-I Wu <olv@lunarg.com> > > Cc: Ville Syrjälä <ville.syrjala@linux.intel.com> > > --- > > 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 b016d9bcd7c1..6b4d1a89e9bc 100644 > > --- a/drivers/gpu/drm/i915/intel_pm.c > > +++ b/drivers/gpu/drm/i915/intel_pm.c > > @@ -4908,9 +4908,11 @@ 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, > > -- > > 1.9.0 > > > > > > -- > olv@LunarG.com
On Tue, Mar 04, 2014 at 05:06:22PM +0200, Ville Syrjälä wrote: > On Tue, Mar 04, 2014 at 10:38:58PM +0800, Chia-I Wu wrote: > > On Tue, Mar 4, 2014 at 5:41 PM, Chris Wilson <chris@chris-wilson.co.uk> wrote: > > > 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. > > I wonder if Haswell GT1 is affected too (that's in another commit). I > > do not own a GT1 for either GEN to verify the issue or to create a > > sensible piglit test. > > I'm seeing corruption on IVB GT2 as well. I might be more blind than > Chris or it's less subtle on GT2 since it took me a while to spot it. > Seems to be easiest to spot in Epic citadel when you go inside the > temple. I can't spot the same corruption on HSW GT3. Queued for -next, thanks for the patch. We can tackle hsw when that on blows up ... -Daniel
diff --git a/drivers/gpu/drm/i915/intel_pm.c b/drivers/gpu/drm/i915/intel_pm.c index b016d9bcd7c1..6b4d1a89e9bc 100644 --- a/drivers/gpu/drm/i915/intel_pm.c +++ b/drivers/gpu/drm/i915/intel_pm.c @@ -4908,9 +4908,11 @@ 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,
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 <chris@chris-wilson.co.uk> Cc: Chia-I Wu <olv@lunarg.com> Cc: Ville Syrjälä <ville.syrjala@linux.intel.com> --- drivers/gpu/drm/i915/intel_pm.c | 8 +++++--- 1 file changed, 5 insertions(+), 3 deletions(-)