3 files changed, 33 insertions, 6 deletions

diff --git a/drivers/gpu/drm/i915/i915_drv.c b/drivers/gpu/drm/i915/i915_drv.c
index 28836fe72211..47a42eb6cc43 100644
--- a/drivers/gpu/drm/i915/i915_drv.c
+++ b/drivers/gpu/drm/i915/i915_drv.c
@@ -63,10 +63,10 @@ module_param_named(semaphores, i915_semaphores, int, 0600);
 MODULE_PARM_DESC(semaphores,
                 "Use semaphores for inter-ring sync (default: false)");
 
-unsigned int i915_enable_rc6 __read_mostly = 0;
+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)");
+                "Enable power-saving render C-state 6 (default: -1 (use per-chip default)");
 
 int i915_enable_fbc __read_mostly = -1;
 module_param_named(i915_enable_fbc, i915_enable_fbc, int, 0600);
diff --git a/drivers/gpu/drm/i915/i915_drv.h b/drivers/gpu/drm/i915/i915_drv.h
index 39a72f642b33..6bcafb5bf7fe 100644
--- a/drivers/gpu/drm/i915/i915_drv.h
+++ b/drivers/gpu/drm/i915/i915_drv.h
@@ -1006,7 +1006,7 @@ extern unsigned int i915_semaphores __read_mostly;
 extern unsigned int i915_lvds_downclock __read_mostly;
 extern int i915_panel_use_ssc __read_mostly;
 extern int i915_vbt_sdvo_panel_type __read_mostly;
-extern unsigned int i915_enable_rc6 __read_mostly;
+extern int i915_enable_rc6 __read_mostly;
 extern int i915_enable_fbc __read_mostly;
 extern bool i915_enable_hangcheck __read_mostly;
 
diff --git a/drivers/gpu/drm/i915/intel_display.c b/drivers/gpu/drm/i915/intel_display.c
index 633c69365388..d544de9e6634 100644
--- a/drivers/gpu/drm/i915/intel_display.c
+++ b/drivers/gpu/drm/i915/intel_display.c
@@ -38,8 +38,8 @@
 #include "i915_drv.h"
 #include "i915_trace.h"
 #include "drm_dp_helper.h"
-
 #include "drm_crtc_helper.h"
+#include <linux/dma_remapping.h>
 
 #define HAS_eDP (intel_pipe_has_type(crtc, INTEL_OUTPUT_EDP))
 
@@ -7887,6 +7887,33 @@ void intel_init_emon(struct drm_device *dev)
         dev_priv->corr = (lcfuse & LCFUSE_HIV_MASK);
 }
 
+static bool intel_enable_rc6(struct drm_device *dev)
+{
+        /*
+         * Respect the kernel parameter if it is set
+         */
+        if (i915_enable_rc6 >= 0)
+                return i915_enable_rc6;
+
+        /*
+         * Disable RC6 on Ironlake
+         */
+        if (INTEL_INFO(dev)->gen == 5)
+                return 0;
+
+        /*
+         * Enable rc6 on Sandybridge if DMA remapping is disabled
+         */
+        if (INTEL_INFO(dev)->gen == 6) {
+                DRM_DEBUG_DRIVER("Sandybridge: intel_iommu_enabled %s -- RC6 %sabled\n",
+                                 intel_iommu_enabled ? "true" : "false",
+                                 !intel_iommu_enabled ? "en" : "dis");
+                return !intel_iommu_enabled;
+        }
+        DRM_DEBUG_DRIVER("RC6 enabled\n");
+        return 1;
+}
+
 void gen6_enable_rps(struct drm_i915_private *dev_priv)
 {
         u32 rp_state_cap = I915_READ(GEN6_RP_STATE_CAP);
@@ -7923,7 +7950,7 @@ void gen6_enable_rps(struct drm_i915_private *dev_priv)
         I915_WRITE(GEN6_RC6p_THRESHOLD, 100000);
         I915_WRITE(GEN6_RC6pp_THRESHOLD, 64000); /* unused */
 
-        if (i915_enable_rc6)
+        if (intel_enable_rc6(dev_priv->dev))
                 rc6_mask = GEN6_RC_CTL_RC6p_ENABLE |
                         GEN6_RC_CTL_RC6_ENABLE;
 
@@ -8372,7 +8399,7 @@ void ironlake_enable_rc6(struct drm_device *dev)
         /* rc6 disabled by default due to repeated reports of hanging during
          * boot and resume.
          */
-        if (!i915_enable_rc6)
+        if (!intel_enable_rc6(dev))
                 return;
 
         mutex_lock(&dev->struct_mutex);