drm/i915: Pack params to engine->schedule() into a struct

Today we only want to pass along the priority to engine->schedule(), but
in the future we want to have much more control over the various aspects
of the GPU during a context's execution, for example controlling the
frequency allowed. As we need an ever growing number of parameters for
scheduling, move those into a struct for convenience.

v2: Move the anonymous struct into its own function for legibility and
ye olde gcc.

Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Reviewed-by: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20180418184052.7129-3-chris@chris-wilson.co.uk

drivers/gpu/drm/i915/intel_ringbuffer.h

@@ -14,6 +14,7 @@
 #include "intel_gpu_commands.h"
 
 struct drm_printer;
+struct i915_sched_attr;
 
 #define I915_CMD_HASH_ORDER 9
 
@@ -460,7 +461,8 @@ struct intel_engine_cs {
 	 *
 	 * Called under the struct_mutex.
 	 */
-	void		(*schedule)(struct i915_request *request, int priority);
+	void		(*schedule)(struct i915_request *request,
+				    const struct i915_sched_attr *attr);
 
 	/*
 	 * Cancel all requests on the hardware, or queued for execution.