[PATCH 0/2]: drm/i915: Disable RC6 and semaphores on SNB *again*

[PATCH 0/2]: drm/i915: Disable RC6 and semaphores on SNB *again*

[Keith Packard]

This leaves them enabled on IVB, but disables them on SNB as we've
discovered (yet again) that there are hardware combinations that
simply cannot run with them.

 [PATCH 1/2] drm/i915: Disable semaphores by default on SNB
 [PATCH 2/2] drm/i915: Disable RC6 on Sandybridge by default

--
keith.packard@intel.com

[PATCH 1/2] drm/i915: Disable semaphores by default on SNB

[Keith Packard]

Semaphores still cause problems on some machines:

> From Udo Steinberg:
>
> With Linux-3.2-rc6 I'm frequently seeing GPU hangs when large amounts of
> text scroll in an xterm, such as when extracting a tar archive. Such as this
> one (note the timestamps):
>
>  I can reproduce it fairly easily with something
>  as simple as:
>
>	  while true; do dmesg; done

This patch turns them off on SNB while leaving them on for IVB.

Reported-by: Udo Steinberg <udo@hypervisor.org>
Cc: Daniel Vetter <daniel@ffwll.ch>
Cc: Eugeni Dodonov <eugeni@dodonov.net>
Signed-off-by: Keith Packard <keithp@keithp.com>
---
 drivers/gpu/drm/i915/i915_gem_execbuffer.c |    4 ++--
 1 files changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/gpu/drm/i915/i915_gem_execbuffer.c b/drivers/gpu/drm/i915/i915_gem_execbuffer.c
index c681dc1..b9da890 100644
--- a/drivers/gpu/drm/i915/i915_gem_execbuffer.c
+++ b/drivers/gpu/drm/i915/i915_gem_execbuffer.c
@@ -756,9 +756,9 @@ intel_enable_semaphores(struct drm_device *dev)
 	if (i915_semaphores >= 0)
 		return i915_semaphores;
 
-	/* Enable semaphores on SNB when IO remapping is off */
+	/* Disable semaphores on SNB */
 	if (INTEL_INFO(dev)->gen == 6)
-		return !intel_iommu_enabled;
+		return 0;
 
 	return 1;
 }
-- 
1.7.7.3

[PATCH 2/2] drm/i915: Disable RC6 on Sandybridge by default

[Keith Packard]

RC6 fails again.

> I found my system freeze mostly during starting up X and KDE. Sometimes it
> works for some minutes, sometimes it freezes immediatly. When the freeze
> happens, everything is dead (even the reset button does not work, I need to
> power cycle).

> I disabled RC6, and my system runs wonderfully.

> The system is a Z68 Pro board with Sandybridge i5-2500K processor, 8
> GB of RAM and UEFI firmware.

Reported-by: Kai Krakow <hurikhan77@gmail.com>
Signed-off-by: Keith Packard <keithp@keithp.com>
---
 drivers/gpu/drm/i915/intel_display.c |    8 +++-----
 1 files changed, 3 insertions(+), 5 deletions(-)

diff --git a/drivers/gpu/drm/i915/intel_display.c b/drivers/gpu/drm/i915/intel_display.c
index 8a61b81..4b7a0f2 100644
--- a/drivers/gpu/drm/i915/intel_display.c
+++ b/drivers/gpu/drm/i915/intel_display.c
@@ -7922,13 +7922,11 @@ static bool intel_enable_rc6(struct drm_device *dev)
 		return 0;
 
 	/*
-	 * Enable rc6 on Sandybridge if DMA remapping is disabled
+	 * Disable rc6 on Sandybridge
 	 */
 	if (INTEL_INFO(dev)->gen == 6) {
-		DRM_DEBUG_DRIVER("Sandybridge: intel_iommu_enabled %s -- RC6 %sabled\n",
-				 intel_iommu_enabled ? "true" : "false",
-				 !intel_iommu_enabled ? "en" : "dis");
-		return !intel_iommu_enabled;
+		DRM_DEBUG_DRIVER("Sandybridge: RC6 disabled\n");
+		return 0;
 	}
 	DRM_DEBUG_DRIVER("RC6 enabled\n");
 	return 1;
-- 
1.7.7.3

Re: [PATCH 0/2]: drm/i915: Disable RC6 and semaphores on SNB *again*

[Linus Torvalds]

On Mon, Dec 26, 2011 at 5:02 PM, Keith Packard <keithp@keithp.com> wrote:
> This leaves them enabled on IVB, but disables them on SNB as we've
> discovered (yet again) that there are hardware combinations that
> simply cannot run with them.

Oh well.

Applied,

               Linus