From: Chris Wilson Date: Tue, 10 Apr 2012 10:52:50 +0000 (+0100) Subject: drm/i915: Allow concurrent read access between CPU and GPU domain X-Git-Url: https://git.karo-electronics.de/?a=commitdiff_plain;h=f84131905b9b3b02b1c5061c0720e503c8d22778;p=linux-beck.git 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 --- diff --git a/drivers/gpu/drm/i915/i915_gem.c b/drivers/gpu/drm/i915/i915_gem.c index d75a6577b97a..1bfb0d28e438 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);