We stopped supporting fallback to execlists in commit 
121981fafe69
(drm/i915/guc: Combine enable_guc_loading|submission modparams). We
do instead reset and retry in some cases, depending on the workarounds
required by the platform.
Cc: Michal Wajdeczko <michal.wajdeczko@intel.com>
Cc: Chris Wilson <chris@chris-wilson.co.uk>
Signed-off-by: Daniele Ceraolo Spurio <daniele.ceraolospurio@intel.com>
Reviewed-by: Michal Wajdeczko <michal.wajdeczko@intel.com>
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Link: https://patchwork.freedesktop.org/patch/msgid/20181022230427.5616-4-daniele.ceraolospurio@intel.com
         * NB: Docs recommend not using the interrupt for completion.
         * Measurements indicate this should take no more than 20ms, so a
         * timeout here indicates that the GuC has failed and is unusable.
-        * (Higher levels of the driver will attempt to fall back to
-        * execlist mode if this happens.)
+        * (Higher levels of the driver may decide to reset the GuC and
+        * attempt the ucode load again if this happens.)
         */
        ret = wait_for(guc_ready(guc, &status), 100);
        DRM_DEBUG_DRIVER("GuC status %#x\n", status);