drm/i915: Shut up GuC errors when it's disabled

DRM_ERROR an continue without any issues aren't allowed since that
causes noise in the CI system. But we absolutely want to have the
DRM_ERROR when we want to run with GuC.

For simplicity just short-circuit all the loader code when it's not
needed.

v2: Mika&Chris complained that I shouldn't hit send on patches written
before coffee kicks in.

v3: Make it compile at least ...

Cc: Alex Dai <yu.dai@intel.com>
Cc: Dave Gordon <david.s.gordon@intel.com>
Cc: Mika Kuoppala <mika.kuoppala@intel.com>
Cc: Chris Wilson <chris@chris-wilson.co.uk>
Signed-off-by: Daniel Vetter <daniel.vetter@intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/1445591459-4327-1-git-send-email-daniel.vetter@ffwll.ch
Reviewed-by: Mika Kuoppala <mika.kuoppala@intel.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>

drivers/gpu/drm/i915/i915_gem.c

@@ -4769,18 +4769,9 @@ i915_gem_init_hw(struct drm_device *dev)
 	if (HAS_GUC_UCODE(dev)) {
 		ret = intel_guc_ucode_load(dev);
 		if (ret) {
-			/*
-			 * If we got an error and GuC submission is enabled, map
-			 * the error to -EIO so the GPU will be declared wedged.
-			 * OTOH, if we didn't intend to use the GuC anyway, just
-			 * discard the error and carry on.
-			 */
-			DRM_ERROR("Failed to initialize GuC, error %d%s\n", ret,
-				  i915.enable_guc_submission ? "" :
-				  " (ignored)");
-			ret = i915.enable_guc_submission ? -EIO : 0;
-			if (ret)
-				goto out;
+			DRM_ERROR("Failed to initialize GuC, error %d\n", ret);
+			ret = -EIO;
+			goto out;
 		}
 	}
 

drivers/gpu/drm/i915/intel_guc_loader.c

@@ -364,6 +364,9 @@ int intel_guc_ucode_load(struct drm_device *dev)
 	struct intel_guc_fw *guc_fw = &dev_priv->guc.guc_fw;
 	int err = 0;
 
+	if (!i915.enable_guc_submission)
+		return 0;
+
 	DRM_DEBUG_DRIVER("GuC fw status: fetch %s, load %s\n",
 		intel_guc_fw_status_repr(guc_fw->guc_fw_fetch_status),
 		intel_guc_fw_status_repr(guc_fw->guc_fw_load_status));
@@ -589,6 +592,9 @@ void intel_guc_ucode_init(struct drm_device *dev)
 		fw_path = "";	/* unknown device */
 	}
 
+	if (!i915.enable_guc_submission)
+		return;
+
 	guc_fw->guc_dev = dev;
 	guc_fw->guc_fw_path = fw_path;
 	guc_fw->guc_fw_fetch_status = GUC_FIRMWARE_NONE;