drm/i915/uc: Add function to define defaults for GuC/HuC enable

There is a module parameter for controlling what GuC/HuC features are
enabled. Setting to -1 means 'use the default'. However, the default
was not well defined, out of date and needs to be different across
platforms.

The default is now to disable both GuC and HuC on legacy platforms
where legacy means TGL/RKL and anything prior to Gen12. For new
platforms, the default is to load HuC but not enable GuC submission
as that has not landed yet.

Signed-off-by: John Harrison <John.C.Harrison@Intel.com>
Reviewed-by: Daniele Ceraolo Spurio <daniele.ceraolospurio@intel.com>
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Link: https://patchwork.freedesktop.org/patch/msgid/20210113220724.2484897-1-John.C.Harrison@Intel.com

drivers/gpu/drm/i915/gt/uc/intel_uc.c

@@ -15,6 +15,29 @@
 static const struct intel_uc_ops uc_ops_off;
 static const struct intel_uc_ops uc_ops_on;
 
+static void uc_expand_default_options(struct intel_uc *uc)
+{
+	struct drm_i915_private *i915 = uc_to_gt(uc)->i915;
+
+	if (i915->params.enable_guc != -1)
+		return;
+
+	/* Don't enable GuC/HuC on pre-Gen12 */
+	if (INTEL_GEN(i915) < 12) {
+		i915->params.enable_guc = 0;
+		return;
+	}
+
+	/* Don't enable GuC/HuC on older Gen12 platforms */
+	if (IS_TIGERLAKE(i915) || IS_ROCKETLAKE(i915)) {
+		i915->params.enable_guc = 0;
+		return;
+	}
+
+	/* Default: enable HuC authentication only */
+	i915->params.enable_guc = ENABLE_GUC_LOAD_HUC;
+}
+
 /* Reset GuC providing us with fresh state for both GuC and HuC.
  */
 static int __intel_uc_reset_hw(struct intel_uc *uc)
@@ -52,9 +75,6 @@ static void __confirm_options(struct intel_uc *uc)
 		yesno(intel_uc_wants_guc_submission(uc)),
 		yesno(intel_uc_wants_huc(uc)));
 
-	if (i915->params.enable_guc == -1)
-		return;
-
 	if (i915->params.enable_guc == 0) {
 		GEM_BUG_ON(intel_uc_wants_guc(uc));
 		GEM_BUG_ON(intel_uc_wants_guc_submission(uc));
@@ -79,15 +99,16 @@ static void __confirm_options(struct intel_uc *uc)
 			 "Incompatible option enable_guc=%d - %s\n",
 			 i915->params.enable_guc, "GuC submission is N/A");
 
-	if (i915->params.enable_guc & ~(ENABLE_GUC_SUBMISSION |
-					  ENABLE_GUC_LOAD_HUC))
+	if (i915->params.enable_guc & ~ENABLE_GUC_MASK)
 		drm_info(&i915->drm,
 			 "Incompatible option enable_guc=%d - %s\n",
 			 i915->params.enable_guc, "undocumented flag");
 }
 
 void intel_uc_init_early(struct intel_uc *uc)
 {
+	uc_expand_default_options(uc);
+
 	intel_guc_init_early(&uc->guc);
 	intel_huc_init_early(&uc->huc);
 

drivers/gpu/drm/i915/gt/uc/intel_uc_fw.c

@@ -152,16 +152,11 @@ __uc_fw_auto_select(struct drm_i915_private *i915, struct intel_uc_fw *uc_fw)
 			uc_fw->path = NULL;
 		}
 	}
-
-	/* We don't want to enable GuC/HuC on pre-Gen11 by default */
-	if (i915->params.enable_guc == -1 && p < INTEL_ICELAKE)
-		uc_fw->path = NULL;
 }
 
 static const char *__override_guc_firmware_path(struct drm_i915_private *i915)
 {
-	if (i915->params.enable_guc & (ENABLE_GUC_SUBMISSION |
-				       ENABLE_GUC_LOAD_HUC))
+	if (i915->params.enable_guc & ENABLE_GUC_MASK)
 		return i915->params.guc_firmware_path;
 	return "";
 }

drivers/gpu/drm/i915/i915_params.h

@@ -32,6 +32,7 @@ struct drm_printer;
 
 #define ENABLE_GUC_SUBMISSION		BIT(0)
 #define ENABLE_GUC_LOAD_HUC		BIT(1)
+#define ENABLE_GUC_MASK			GENMASK(1, 0)
 
 /*
  * Invoke param, a function-like macro, for each i915 param, with arguments: