drm/i915/guc: Don't enable GuC/HuC in auto mode on pre-Gen11

We are about to change default setting of "enable_guc" modparam
from 0(disabled) to -1(auto). As we only want to turn on
GuC/HuC on Gen11+, keep it off for older gens.

Note that it would be still possible to enable GuC/HuC on these
old platforms using explicit "enable_guc=2" modparam.
Signed-off-by: Michal Wajdeczko <michal.wajdeczko@intel.com>
Cc: Jani Nikula <jani.nikula@intel.com>
Cc: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>
Cc: Rodrigo Vivi <rodrigo.vivi@intel.com>
Cc: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Daniele Ceraolo Spurio <daniele.ceraolospurio@intel.com>
Reviewed-by: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>
Reviewed-by: Rodrigo Vivi <rodrigo.vivi@intel.com>
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Link: https://patchwork.freedesktop.org/patch/msgid/20190712111445.21040-2-michal.wajdeczko@intel.com

drivers/gpu/drm/i915/intel_uc.c

@@ -58,12 +58,16 @@ static int __get_platform_enable_guc(struct drm_i915_private *i915)
 	struct intel_uc_fw *huc_fw = &i915->huc.fw;
 	int enable_guc = 0;
 
-	/* Default is to use HuC if we know GuC and HuC firmwares */
+	if (!HAS_GUC(i915))
+		return 0;
+
+	/* We don't want to enable GuC/HuC on pre-Gen11 by default */
+	if (INTEL_GEN(i915) < 11)
+		return 0;
+
 	if (intel_uc_fw_is_selected(guc_fw) && intel_uc_fw_is_selected(huc_fw))
 		enable_guc |= ENABLE_GUC_LOAD_HUC;
 
-	/* Any platform specific fine-tuning can be done here */
-
 	return enable_guc;
 }