From 7aa6ca61ee5546d74b76610894924cdb0d4a1af0 Mon Sep 17 00:00:00 2001 From: Chris Wilson Date: Mon, 7 Nov 2016 16:52:04 +0000 Subject: [PATCH] drm/i915: Mark CPU cache as dirty when used for rendering MIME-Version: 1.0 Content-Type: text/plain; charset=utf8 Content-Transfer-Encoding: 8bit On LLC, or even snooped, machines rendering via the GPU ends up in the CPU cache. This cacheline dirt also needs to be flushed to main memory when moving to an incoherent domain, such as the display's scanout engine. Mostly, this happens because either the object is marked as dirty from its first use or is avoided by setting the object into the display domain from the start. v2: Treat WT as not requiring a clflush prior to use on the display engine as well. Fixes: 0f71979ab7fb ("drm/i915: Performed deferred clflush inside set-cache-level") References: https://bugs.freedesktop.org/show_bug.cgi?id=95414 Signed-off-by: Chris Wilson Cc: Jani Nikula Cc: Ville Syrjälä Cc: # v4.0+ Reviewed-by: Ville Syrjälä Link: http://patchwork.freedesktop.org/patch/msgid/20161107165204.7008-1-chris@chris-wilson.co.uk --- drivers/gpu/drm/i915/i915_gem_execbuffer.c | 8 ++++++++ 1 file changed, 8 insertions(+) diff --git a/drivers/gpu/drm/i915/i915_gem_execbuffer.c b/drivers/gpu/drm/i915/i915_gem_execbuffer.c index 322c580a739f..fb5b44339f71 100644 --- a/drivers/gpu/drm/i915/i915_gem_execbuffer.c +++ b/drivers/gpu/drm/i915/i915_gem_execbuffer.c @@ -1247,6 +1247,12 @@ i915_gem_validate_context(struct drm_device *dev, struct drm_file *file, return ctx; } +static bool gpu_write_needs_clflush(struct drm_i915_gem_object *obj) +{ + return !(obj->cache_level == I915_CACHE_NONE || + obj->cache_level == I915_CACHE_WT); +} + void i915_vma_move_to_active(struct i915_vma *vma, struct drm_i915_gem_request *req, unsigned int flags) @@ -1276,6 +1282,8 @@ void i915_vma_move_to_active(struct i915_vma *vma, /* update for the implicit flush after a batch */ obj->base.write_domain &= ~I915_GEM_GPU_DOMAINS; + if (!obj->cache_dirty && gpu_write_needs_clflush(obj)) + obj->cache_dirty = true; } if (flags & EXEC_OBJECT_NEEDS_FENCE) -- 2.20.1