From: Keith Packard <keithp@keithp.com>
Date: Tue, 27 Dec 2011 01:02:10 +0000 (-0800)
Subject: drm/i915: Disable semaphores by default on SNB
X-Git-Tag: v5.15~23502
X-Git-Url: https://git.proxmox.com/?a=commitdiff_plain;h=ebbd857e6b9a92c0aff4aacd1b1d2361d888633e;p=mirror_ubuntu-kernels.git

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 c681dc149d2a..b9da8900ae4e 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;
 }