[PATCH] drm/i915: Bail if we do not setup the RCS engine

[Chris Wilson <chris@chris-wilson.co.uk>]

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.

Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
---
 drivers/gpu/drm/i915/intel_engine_cs.c | 8 +++++++-
 1 file changed, 7 insertions(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/i915/intel_engine_cs.c b/drivers/gpu/drm/i915/intel_engine_cs.c
index 71e89a93fe18..3595209d86cf 100644
--- a/drivers/gpu/drm/i915/intel_engine_cs.c
+++ b/drivers/gpu/drm/i915/intel_engine_cs.c
@@ -154,9 +154,9 @@ 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;
 	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_i915_private *dev_priv)
 	if (WARN_ON(mask != ring_mask))
 		device_info->ring_mask = mask;
 
+	/* We always presume we have at least RCS available for probing */
+	if (WARN_ON(!(mask & ENGINE_MASK(RCS)))) {
+		err = -ENODEV;
+		goto cleanup;
+	}
+
 	device_info->num_rings = hweight32(mask);
 
 	return 0;
-- 
2.11.0

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