drm/i915: Use the precomputed value for whether to enable command parsing

As i915.enable_cmd_parser is an unsafe option, make it read-only at
runtime. Now that it is constant, we can use the value determined during
initialisation as to whether we need the cmdparser at execbuffer time.

v2: Remove the inline for its single user, it is clear enough (and
shorter) without!

Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Reviewed-by: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/20161124125851.6615-1-chris@chris-wilson.co.uk

drivers/gpu/drm/i915/i915_cmd_parser.c

@@ -1131,27 +1131,6 @@ unpin_src:
 	return dst;
 }
 
-/**
- * intel_engine_needs_cmd_parser() - should a given engine use software
- *                                   command parsing?
- * @engine: the engine in question
- *
- * Only certain platforms require software batch buffer command parsing, and
- * only when enabled via module parameter.
- *
- * Return: true if the engine requires software command parsing
- */
-bool intel_engine_needs_cmd_parser(struct intel_engine_cs *engine)
-{
-	if (!engine->needs_cmd_parser)
-		return false;
-
-	if (!USES_PPGTT(engine->i915))
-		return false;
-
-	return (i915.enable_cmd_parser == 1);
-}
-
 static bool check_cmd(const struct intel_engine_cs *engine,
 		      const struct drm_i915_cmd_descriptor *desc,
 		      const u32 *cmd, u32 length,
@@ -1375,7 +1354,7 @@ int i915_cmd_parser_get_version(struct drm_i915_private *dev_priv)
 
 	/* If the command parser is not enabled, report 0 - unsupported */
 	for_each_engine(engine, dev_priv, id) {
-		if (intel_engine_needs_cmd_parser(engine)) {
+		if (engine->needs_cmd_parser) {
 			active = true;
 			break;
 		}

drivers/gpu/drm/i915/i915_drv.h

@@ -3452,7 +3452,6 @@ const char *i915_cache_level_str(struct drm_i915_private *i915, int type);
 int i915_cmd_parser_get_version(struct drm_i915_private *dev_priv);
 void intel_engine_init_cmd_parser(struct intel_engine_cs *engine);
 void intel_engine_cleanup_cmd_parser(struct intel_engine_cs *engine);
-bool intel_engine_needs_cmd_parser(struct intel_engine_cs *engine);
 int intel_engine_cmd_parser(struct intel_engine_cs *engine,
 			    struct drm_i915_gem_object *batch_obj,
 			    struct drm_i915_gem_object *shadow_batch_obj,

drivers/gpu/drm/i915/i915_gem_execbuffer.c

@@ -1713,7 +1713,7 @@ i915_gem_do_execbuffer(struct drm_device *dev, void *data,
 	}
 
 	params->args_batch_start_offset = args->batch_start_offset;
-	if (intel_engine_needs_cmd_parser(engine) && args->batch_len) {
+	if (engine->needs_cmd_parser && args->batch_len) {
 		struct i915_vma *vma;
 
 		vma = i915_gem_execbuffer_parse(engine, &shadow_exec_entry,

drivers/gpu/drm/i915/i915_params.c

@@ -50,7 +50,7 @@ struct i915_params i915 __read_mostly = {
 	.error_capture = true,
 	.invert_brightness = 0,
 	.disable_display = 0,
-	.enable_cmd_parser = 1,
+	.enable_cmd_parser = true,
 	.use_mmio_flip = 0,
 	.mmio_debug = 0,
 	.verbose_state_checks = 1,
@@ -188,9 +188,9 @@ MODULE_PARM_DESC(invert_brightness,
 module_param_named(disable_display, i915.disable_display, bool, 0400);
 MODULE_PARM_DESC(disable_display, "Disable display (default: false)");
 
-module_param_named_unsafe(enable_cmd_parser, i915.enable_cmd_parser, int, 0600);
+module_param_named_unsafe(enable_cmd_parser, i915.enable_cmd_parser, bool, 0400);
 MODULE_PARM_DESC(enable_cmd_parser,
-		 "Enable command parsing (1=enabled [default], 0=disabled)");
+		 "Enable command parsing (true=enabled [default], false=disabled)");
 
 module_param_named_unsafe(use_mmio_flip, i915.use_mmio_flip, int, 0600);
 MODULE_PARM_DESC(use_mmio_flip,

drivers/gpu/drm/i915/i915_params.h

@@ -44,7 +44,6 @@ struct i915_params {
 	int disable_power_well;
 	int enable_ips;
 	int invert_brightness;
-	int enable_cmd_parser;
 	int enable_guc_loading;
 	int enable_guc_submission;
 	int guc_log_level;
@@ -53,6 +52,7 @@ struct i915_params {
 	int edp_vswing;
 	unsigned int inject_load_failure;
 	/* leave bools at the end to not create holes */
+	bool enable_cmd_parser;
 	bool enable_hangcheck;
 	bool fastboot;
 	bool prefault_disable;