drm/i915/bdw: Enable execlists by default where supported

Execlist support in the i915 driver is now considered good enough for the
feature to be enabled by default on Gen8 and later and routinely tested.
Adjusted i915 parameters structure initialization to reflect this and updated
the comment in intel_sanitize_enable_execlists().

There's still work to do before we can let the wider massive onto it,
but there's still time left before the 3.20 cutoff.

v2: Update the MODULE_PARM_DESC too.

Issue: VIZ-2020
Signed-off-by: Thomas Daniel <thomas.daniel@intel.com>
[danvet: Add note that there's still some work left to do.]
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>

drivers/gpu/drm/i915/i915_params.c

@@ -35,7 +35,7 @@ struct i915_params i915 __read_mostly = {
 	.vbt_sdvo_panel_type = -1,
 	.enable_rc6 = -1,
 	.enable_fbc = -1,
-	.enable_execlists = 0,
+	.enable_execlists = -1,
 	.enable_hangcheck = true,
 	.enable_ppgtt = -1,
 	.enable_psr = 0,
@@ -122,7 +122,7 @@ MODULE_PARM_DESC(enable_ppgtt,
 module_param_named(enable_execlists, i915.enable_execlists, int, 0400);
 MODULE_PARM_DESC(enable_execlists,
 	"Override execlists usage. "
-	"(-1=auto, 0=disabled [default], 1=enabled)");
+	"(-1=auto [default], 0=disabled, 1=enabled)");
 
 module_param_named(enable_psr, i915.enable_psr, int, 0600);
 MODULE_PARM_DESC(enable_psr, "Enable PSR (default: false)");

drivers/gpu/drm/i915/intel_lrc.c

@@ -212,8 +212,7 @@ static int intel_lr_context_pin(struct intel_engine_cs *ring,
  * @enable_execlists: value of i915.enable_execlists module parameter.
  *
  * Only certain platforms support Execlists (the prerequisites being
- * support for Logical Ring Contexts and Aliasing PPGTT or better),
- * and only when enabled via module parameter.
+ * support for Logical Ring Contexts and Aliasing PPGTT or better).
  *
  * Return: 1 if Execlists is supported and has to be enabled.
  */