drm/i915: Warn about missing context state workarounds only once

Otherwise, new platforms without workarounds will hit this warning for
every new context created.

Cc: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
Signed-off-by: Michel Thierry <michel.thierry@intel.com>
Reviewed-by: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>

drivers/gpu/drm/i915/intel_lrc.c

@@ -1096,7 +1096,7 @@ static int intel_logical_ring_workarounds_emit(struct intel_engine_cs *ring,
 	struct drm_i915_private *dev_priv = dev->dev_private;
 	struct i915_workarounds *w = &dev_priv->workarounds;
 
-	if (WARN_ON(w->count == 0))
+	if (WARN_ON_ONCE(w->count == 0))
 		return 0;
 
 	ring->gpu_caches_dirty = true;

drivers/gpu/drm/i915/intel_ringbuffer.c

@@ -679,7 +679,7 @@ static int intel_ring_workarounds_emit(struct intel_engine_cs *ring,
 	struct drm_i915_private *dev_priv = dev->dev_private;
 	struct i915_workarounds *w = &dev_priv->workarounds;
 
-	if (WARN_ON(w->count == 0))
+	if (WARN_ON_ONCE(w->count == 0))
 		return 0;
 
 	ring->gpu_caches_dirty = true;