drm/i915: Generate the engine name based on the instance number

Not really needed, but makes the next change a little bit more compact.

v2:
  - Use zero-based numbering for engine names: xcs0, xcs1.. xcsN (Tvrtko, Chris)
  - Make sure the mock engine name is null-terminated (Tvrtko, Chris)

v3: Because I'm stupid (Chris)

v4: Verify engine name wasn't truncated (Michal)

v5:
  - Kill the warning in mock engine (Chris)

Cc: Paulo Zanoni <paulo.r.zanoni@intel.com>
Cc: Rodrigo Vivi <rodrigo.vivi@intel.com>
Cc: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Daniele Ceraolo Spurio <daniele.ceraolospurio@intel.com>
Reviewed-by: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
Reviewed-by: Michal Wajdeczko <michal.wajdeczko@intel.com>
Signed-off-by: Oscar Mateo <oscar.mateo@intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/1491834873-9345-4-git-send-email-oscar.mateo@intel.comReviewed-by: Chris Wilson <chris@chris-wilson.co.uk>
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>

drivers/gpu/drm/i915/intel_engine_cs.c

@@ -71,7 +71,7 @@ static const struct engine_info {
 		.init_legacy = intel_init_bsd_ring_buffer,
 	},
 	[VCS2] = {
-		.name = "vcs2",
+		.name = "vcs",
 		.hw_id = VCS2_HW,
 		.exec_id = I915_EXEC_BSD,
 		.class = VIDEO_DECODE_CLASS,
@@ -108,7 +108,8 @@ intel_engine_setup(struct drm_i915_private *dev_priv,
 
 	engine->id = id;
 	engine->i915 = dev_priv;
-	engine->name = info->name;
+	WARN_ON(snprintf(engine->name, sizeof(engine->name), "%s%u",
+			 info->name, info->instance) >= sizeof(engine->name));
 	engine->exec_id = info->exec_id;
 	engine->hw_id = engine->guc_id = info->hw_id;
 	engine->mmio_base = info->mmio_base;

drivers/gpu/drm/i915/intel_ringbuffer.h

@@ -187,9 +187,11 @@ enum intel_engine_id {
 	VECS
 };
 
+#define INTEL_ENGINE_CS_MAX_NAME 8
+
 struct intel_engine_cs {
 	struct drm_i915_private *i915;
-	const char	*name;
+	char name[INTEL_ENGINE_CS_MAX_NAME];
 	enum intel_engine_id id;
 	unsigned int exec_id;
 	unsigned int hw_id;

drivers/gpu/drm/i915/selftests/mock_engine.c

@@ -140,7 +140,7 @@ struct intel_engine_cs *mock_engine(struct drm_i915_private *i915,
 
 	/* minimal engine setup for requests */
 	engine->base.i915 = i915;
-	engine->base.name = name;
+	snprintf(engine->base.name, sizeof(engine->base.name), "%s", name);
 	engine->base.id = id++;
 	engine->base.status_page.page_addr = (void *)(engine + 1);