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 | 2 +- 1 files changed, 1 insertions(+), 1 deletions(-)

diff --git a/drivers/gpu/drm/i915/i915_gem_execbuffer.c b/drivers/gpu/drm/i915/i915_gem_execbuffer.c index c681dc1..0d4d308 100644 --- a/drivers/gpu/drm/i915/i915_gem_execbuffer.c +++ b/drivers/gpu/drm/i915/i915_gem_execbuffer.c @@ -758,7 +758,7 @@ intel_enable_semaphores(struct drm_device *dev)

/* Enable semaphores on SNB when IO remapping is off */ if (INTEL_INFO(dev)->gen == 6) - return !intel_iommu_enabled; + return 0;

return 1; }