[PATCH 3/3] drm/i915: re-enable rc6 by default when GMAR is disabled

[Eugeni Dodonov <eugeni.dodonov@intel.com>]

Most of the rc6-related hangs and major issues were addressed for the past
months.

Let's re-enable it by default to provide a more wider testing, and catch
the remaining problems.

According to tests, enablement of rc6 results in up to +50% improvements
in power usage and battery life, so it certainly would be a nice feature
to have enabled by default.

Also, most of the rc6-related issues seem to came from GMAR, so we only
enable it as long as GMAR is disabled.

CC: Keith Packard <keithp@keithp.com>
CC: Daniel Vetter <daniel.vetter@ffwll.ch>
CC: Jesse Barnes <jbarnes@virtuousgeek.org>
Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=38567
Signed-off-by: Eugeni Dodonov <eugeni.dodonov@intel.com>
---
 drivers/gpu/drm/i915/i915_drv.c      |    2 +-
 drivers/gpu/drm/i915/intel_display.c |    3 ++-
 2 files changed, 3 insertions(+), 2 deletions(-)

diff --git a/drivers/gpu/drm/i915/i915_drv.c b/drivers/gpu/drm/i915/i915_drv.c
index 565725c..337a568 100644
--- a/drivers/gpu/drm/i915/i915_drv.c
+++ b/drivers/gpu/drm/i915/i915_drv.c
@@ -63,7 +63,7 @@ module_param_named(semaphores, i915_semaphores, int, 0600);
 MODULE_PARM_DESC(semaphores,
 		"Use semaphores for inter-ring sync (default: -1 (use per-chip defaults))");
 
-unsigned int i915_enable_rc6 __read_mostly = 0;
+unsigned int i915_enable_rc6 __read_mostly = 1;
 module_param_named(i915_enable_rc6, i915_enable_rc6, int, 0600);
 MODULE_PARM_DESC(i915_enable_rc6,
 		"Enable power-saving render C-state 6 (default: true)");
diff --git a/drivers/gpu/drm/i915/intel_display.c b/drivers/gpu/drm/i915/intel_display.c
index 981b1f1..5dd0878 100644
--- a/drivers/gpu/drm/i915/intel_display.c
+++ b/drivers/gpu/drm/i915/intel_display.c
@@ -31,6 +31,7 @@
 #include <linux/kernel.h>
 #include <linux/slab.h>
 #include <linux/vgaarb.h>
+#include <linux/intel-iommu.h>
 #include <drm/drm_edid.h>
 #include "drmP.h"
 #include "intel_drv.h"
@@ -8746,7 +8747,7 @@ void intel_modeset_init(struct drm_device *dev)
 
 void intel_modeset_gem_init(struct drm_device *dev)
 {
-	if (IS_IRONLAKE_M(dev))
+	if (IS_IRONLAKE_M(dev) && dmar_disabled)
 		ironlake_enable_rc6(dev);
 
 	intel_setup_overlay(dev);
-- 
1.7.7.3