drm/i915/huc: Adjust HuC state accordingly after GuC fetch error

Firmware "Selected" state is a transient state - we don't expect to see
it after finishing driver probe, we even have asserts sprinkled over
i915 to confirm whether that's the case.
Unfortunately - we don't handle the transition out of "Selected" in case
of GuC fetch error, leading those asserts to fire when calling
"intel_huc_is_used()".

v2: Add dbg print when moving HuC into error state (Daniele)
Reported-by: Marcin Bernatowicz <marcin.bernatowicz@intel.com>
Signed-off-by: Michał Winiarski <michal.winiarski@intel.com>
Cc: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Daniele Ceraolo Spurio <daniele.ceraolospurio@intel.com>
Cc: Marcin Bernatowicz <marcin.bernatowicz@intel.com>
Cc: Michal Wajdeczko <michal.wajdeczko@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/20200708100843.297655-2-michal@hardline.pl

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

@@ -267,8 +267,17 @@ static void __uc_fetch_firmwares(struct intel_uc *uc)
 	GEM_BUG_ON(!intel_uc_wants_guc(uc));
 
 	err = intel_uc_fw_fetch(&uc->guc.fw);
-	if (err)
+	if (err) {
+		/* Make sure we transition out of transient "SELECTED" state */
+		if (intel_uc_wants_huc(uc)) {
+			drm_dbg(&uc_to_gt(uc)->i915->drm,
+				"Failed to fetch GuC: %d disabling HuC\n", err);
+			intel_uc_fw_change_status(&uc->huc.fw,
+						  INTEL_UC_FIRMWARE_ERROR);
+		}
+
 		return;
+	}
 
 	if (intel_uc_wants_huc(uc))
 		intel_uc_fw_fetch(&uc->huc.fw);