From f84131905b9b3b02b1c5061c0720e503c8d22778 Mon Sep 17 00:00:00 2001 From: Chris Wilson Date: Tue, 10 Apr 2012 11:52:50 +0100 Subject: [PATCH] drm/i915: Allow concurrent read access between CPU and GPU domain Similar to allowing a buffer to be simultaneously read by the GPU and through the GTT, we wish to allow readback of the pages through the CPU domain whilst they are also being read by the GPU. Domain coherency is managed by allowing multiple readers, but only a single writer. This is used by mesa for its program cache which it may search for every new program every frame and then renews should it need to add. During renewal, mesa copies the program bo currently executing through a CPU mapping onto the new bo. This patch allows the search and that copy to proceed without causing a stall on the current batch. Testcase: i-g-t/tests/gem_cpu_concurrent_blit Signed-off-by: Chris Wilson Reviewed-by: Daniel Vetter Signed-Off-by: Daniel Vetter --- drivers/gpu/drm/i915/i915_gem.c | 8 +++++--- 1 file changed, 5 insertions(+), 3 deletions(-) diff --git a/drivers/gpu/drm/i915/i915_gem.c b/drivers/gpu/drm/i915/i915_gem.c index d75a657..1bfb0d2 100644 --- a/drivers/gpu/drm/i915/i915_gem.c +++ b/drivers/gpu/drm/i915/i915_gem.c @@ -3068,9 +3068,11 @@ i915_gem_object_set_to_cpu_domain(struct drm_i915_gem_object *obj, bool write) if (ret) return ret; - ret = i915_gem_object_wait_rendering(obj); - if (ret) - return ret; + if (write || obj->pending_gpu_write) { + ret = i915_gem_object_wait_rendering(obj); + if (ret) + return ret; + } i915_gem_object_flush_gtt_write_domain(obj); -- 2.7.4