From 5f9be05432cb4c323967f6d71ce0ecc024a775c7 Mon Sep 17 00:00:00 2001
From: Chris Wilson <chris@chris-wilson.co.uk>
Date: Tue, 11 Apr 2017 17:56:58 +0100
Subject: [PATCH] drm/i915: Bail if we do not setup the RCS engine
Git-commit: 5f9be05432cb4c323967f6d71ce0ecc024a775c7
Patch-mainline: v4.13-rc1
References: FATE#322643 bsc#1055900

In places, we assume that RCS exists. This has been true forever, but
let us catch this failure during bringup by adding an explicit check
that we do have an RCS engine.

V2: Make use of HAS_ENGINE (Tvrtko)

Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Reviewed-by: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/20170411165658.23828-1-chris@chris-wilson.co.uk
Acked-by: Takashi Iwai <tiwai@suse.de>

---
 drivers/gpu/drm/i915/intel_engine_cs.c |   10 ++++++++--
 1 file changed, 8 insertions(+), 2 deletions(-)

--- a/drivers/gpu/drm/i915/intel_engine_cs.c
+++ b/drivers/gpu/drm/i915/intel_engine_cs.c
@@ -153,10 +153,10 @@ intel_engine_setup(struct drm_i915_priva
 int intel_engines_init_early(struct drm_i915_private *dev_priv)
 {
 	struct intel_device_info *device_info = mkwrite_device_info(dev_priv);
-	unsigned int ring_mask = INTEL_INFO(dev_priv)->ring_mask;
-	unsigned int mask = 0;
+	const unsigned int ring_mask = INTEL_INFO(dev_priv)->ring_mask;
 	struct intel_engine_cs *engine;
 	enum intel_engine_id id;
+	unsigned int mask = 0;
 	unsigned int i;
 	int err;
 
@@ -183,6 +183,12 @@ int intel_engines_init_early(struct drm_
 	if (WARN_ON(mask != ring_mask))
 		device_info->ring_mask = mask;
 
+	/* We always presume we have at least RCS available for later probing */
+	if (WARN_ON(!HAS_ENGINE(dev_priv, RCS))) {
+		err = -ENODEV;
+		goto cleanup;
+	}
+
 	device_info->num_rings = hweight32(mask);
 
 	return 0;