drm/i915: Report command parser version 0 if disabled

If the command parser is not active, then it is appropriate to report it
as operating at version 0 as no higher mode is supported. This greatly
simplifies userspace querying for the command parser as we then do not
need to second guess when it will be active (a mixture of module
parameters and generational support, which may change over time).

v2: s/comand/command/ misspelling in comment
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Link: http://patchwork.freedesktop.org/patch/msgid/1462368336-21230-1-git-send-email-chris@chris-wilson.co.ukReviewed-by: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>

drivers/gpu/drm/i915/i915_cmd_parser.c

@@ -1275,8 +1275,21 @@ int i915_parse_cmds(struct intel_engine_cs *engine,
  *
  * Return: the current version number of the cmd parser
  */
-int i915_cmd_parser_get_version(void)
+int i915_cmd_parser_get_version(struct drm_i915_private *dev_priv)
 {
+	struct intel_engine_cs *engine;
+	bool active = false;
+
+	/* If the command parser is not enabled, report 0 - unsupported */
+	for_each_engine(engine, dev_priv) {
+		if (i915_needs_cmd_parser(engine)) {
+			active = true;
+			break;
+		}
+	}
+	if (!active)
+		return 0;
+
 	/*
 	 * Command parser version history
 	 *

drivers/gpu/drm/i915/i915_dma.c

@@ -204,7 +204,7 @@ static int i915_getparam(struct drm_device *dev, void *data,
 		value = 1;
 		break;
 	case I915_PARAM_CMD_PARSER_VERSION:
-		value = i915_cmd_parser_get_version();
+		value = i915_cmd_parser_get_version(dev_priv);
 		break;
 	case I915_PARAM_HAS_COHERENT_PHYS_GTT:
 		value = 1;

drivers/gpu/drm/i915/i915_drv.h

@@ -3442,7 +3442,7 @@ void i915_get_extra_instdone(struct drm_device *dev, uint32_t *instdone);
 const char *i915_cache_level_str(struct drm_i915_private *i915, int type);
 
 /* i915_cmd_parser.c */
-int i915_cmd_parser_get_version(void);
+int i915_cmd_parser_get_version(struct drm_i915_private *dev_priv);
 int i915_cmd_parser_init_ring(struct intel_engine_cs *engine);
 void i915_cmd_parser_fini_ring(struct intel_engine_cs *engine);
 bool i915_needs_cmd_parser(struct intel_engine_cs *engine);