From a1656b9090f7008d2941c314f5a64724bea2ae37 Mon Sep 17 00:00:00 2001 From: Chris Wilson Date: Fri, 4 Mar 2011 18:48:03 +0000 Subject: [PATCH] drm/i915: Disable GPU semaphores by default Andi Kleen narrowed his GPU hangs on his Sugar Bay (SNB desktop) rev 09 down to the use of GPU semaphores, and we already know that they appear broken up to Huron River (mobile) rev 08. (I'm optimistic that disabling GPU semaphores is simply hiding another bug by the latency and side-effects of the additional device interaction it introduces...) However, use of semaphores is a massive performance improvement... Only as long as the system remains stable. Enable at your peril. Reported-by: Andi Kleen Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=33921 Signed-off-by: Chris Wilson --- drivers/gpu/drm/i915/i915_drv.c | 3 +++ drivers/gpu/drm/i915/i915_drv.h | 1 + drivers/gpu/drm/i915/i915_gem_execbuffer.c | 4 ++-- 3 files changed, 6 insertions(+), 2 deletions(-) diff --git a/drivers/gpu/drm/i915/i915_drv.c b/drivers/gpu/drm/i915/i915_drv.c index 37d672a..22ec066 100644 --- a/drivers/gpu/drm/i915/i915_drv.c +++ b/drivers/gpu/drm/i915/i915_drv.c @@ -46,6 +46,9 @@ module_param_named(fbpercrtc, i915_fbpercrtc, int, 0400); unsigned int i915_powersave = 1; module_param_named(powersave, i915_powersave, int, 0600); +unsigned int i915_semaphores = 0; +module_param_named(semaphores, i915_semaphores, int, 0600); + unsigned int i915_enable_rc6 = 0; module_param_named(i915_enable_rc6, i915_enable_rc6, int, 0600); diff --git a/drivers/gpu/drm/i915/i915_drv.h b/drivers/gpu/drm/i915/i915_drv.h index 549c046..d023b9b 100644 --- a/drivers/gpu/drm/i915/i915_drv.h +++ b/drivers/gpu/drm/i915/i915_drv.h @@ -956,6 +956,7 @@ extern struct drm_ioctl_desc i915_ioctls[]; extern int i915_max_ioctl; extern unsigned int i915_fbpercrtc; extern unsigned int i915_powersave; +extern unsigned int i915_semaphores; extern unsigned int i915_lvds_downclock; extern unsigned int i915_panel_use_ssc; extern unsigned int i915_enable_rc6; diff --git a/drivers/gpu/drm/i915/i915_gem_execbuffer.c b/drivers/gpu/drm/i915/i915_gem_execbuffer.c index d2f445e..50ab161 100644 --- a/drivers/gpu/drm/i915/i915_gem_execbuffer.c +++ b/drivers/gpu/drm/i915/i915_gem_execbuffer.c @@ -772,8 +772,8 @@ i915_gem_execbuffer_sync_rings(struct drm_i915_gem_object *obj, if (from == NULL || to == from) return 0; - /* XXX gpu semaphores are currently causing hard hangs on SNB mobile */ - if (INTEL_INFO(obj->base.dev)->gen < 6 || IS_MOBILE(obj->base.dev)) + /* XXX gpu semaphores are implicated in various hard hangs on SNB */ + if (INTEL_INFO(obj->base.dev)->gen < 6 || !i915_semaphores) return i915_gem_object_wait_rendering(obj, true); idx = intel_ring_sync_index(from, to); -- 2.7.4