From mboxrd@z Thu Jan 1 00:00:00 1970 From: Chris Wilson Subject: [PATCH 2/2] drm/i915: Use the uncached domain for the display planes Date: Fri, 15 Apr 2011 07:04:14 +0100 Message-ID: <1302847454-716-2-git-send-email-chris@chris-wilson.co.uk> References: <1302771827-26112-9-git-send-email-chris@chris-wilson.co.uk> <1302847454-716-1-git-send-email-chris@chris-wilson.co.uk> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: Received: from fireflyinternet.com (server109-228-6-236.live-servers.net [109.228.6.236]) by gabe.freedesktop.org (Postfix) with ESMTP id AEB6D9E9D4 for ; Thu, 14 Apr 2011 23:04:28 -0700 (PDT) In-Reply-To: <1302847454-716-1-git-send-email-chris@chris-wilson.co.uk> List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: intel-gfx-bounces+gcfxdi-intel-gfx=m.gmane.org@lists.freedesktop.org Errors-To: intel-gfx-bounces+gcfxdi-intel-gfx=m.gmane.org@lists.freedesktop.org To: intel-gfx@lists.freedesktop.org List-Id: intel-gfx@lists.freedesktop.org From: Eric Anholt The simplest and common method for ensuring scanout coherency on all chipsets is to mark the scanout buffers as uncached (and for userspace to remember to flush the render cache every so often). We can improve upon this for later generations by marking scanout objects as GFDT and only flush those cachelines when required. However, we start simple. [v2: Move the set to uncached above the clflush. Otherwise, we'd skip the clflush and try to scan out data that was still sitting in the cache.] Signed-off-by: Eric Anholt Signed-off-by: Chris Wilson --- drivers/gpu/drm/i915/i915_gem.c | 13 +++++++++++++ 1 files changed, 13 insertions(+), 0 deletions(-) diff --git a/drivers/gpu/drm/i915/i915_gem.c b/drivers/gpu/drm/i915/i915_gem.c index 9c1ff7d..5e6c504 100644 --- a/drivers/gpu/drm/i915/i915_gem.c +++ b/drivers/gpu/drm/i915/i915_gem.c @@ -3116,6 +3116,19 @@ i915_gem_object_pin_to_display_plane(struct drm_i915_gem_object *obj, return ret; } + /* The display engine is not coherent with the LLC cache on gen6. As + * a result, we make sure that the pinning that is about to occur is + * done with uncached PTEs. This is lowest common denominator for all + * chipsets. + * + * However for gen6+, we could do better by using the GFDT bit instead + * of uncaching, which would allow us to flush all the LLC-cached data + * with that bit in the PTE to main memory with just one PIPE_CONTROL. + */ + ret = i915_gem_object_set_cache_level(obj, I915_CACHE_NONE); + if (ret) + return ret; + ret = i915_gem_object_pin(obj, alignment, true); if (ret) return ret; -- 1.7.4.1