drm/i915: Disable semaphores by default on SNB
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>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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 @@
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;
}