3 files changed, 10 insertions, 0 deletions

diff --git a/drivers/gpu/drm/i915/i915_drv.h b/drivers/gpu/drm/i915/i915_drv.h
index be910d249ea1..63bcda5541ec 100644
--- a/drivers/gpu/drm/i915/i915_drv.h
+++ b/drivers/gpu/drm/i915/i915_drv.h
@@ -924,6 +924,7 @@ struct i915_suspend_saved_registers {
         u32 savePIPEB_LINK_N1;
         u32 saveMCHBAR_RENDER_STANDBY;
         u32 savePCH_PORT_HOTPLUG;
+        u16 saveGCDGMBUS;
 };
 
 struct vlv_s0ix_state {
diff --git a/drivers/gpu/drm/i915/i915_reg.h b/drivers/gpu/drm/i915/i915_reg.h
index b607bbe55261..eefdc238f70b 100644
--- a/drivers/gpu/drm/i915/i915_reg.h
+++ b/drivers/gpu/drm/i915/i915_reg.h
@@ -85,6 +85,7 @@
 #define   I915_GC_RENDER_CLOCK_166_MHZ  (0 << 0)
 #define   I915_GC_RENDER_CLOCK_200_MHZ  (1 << 0)
 #define   I915_GC_RENDER_CLOCK_333_MHZ  (4 << 0)
+#define GCDGMBUS 0xcc
 #define PCI_LBPC 0xf4 /* legacy/combination backlight modes, also called LBB */
 
 
diff --git a/drivers/gpu/drm/i915/i915_suspend.c b/drivers/gpu/drm/i915/i915_suspend.c
index dfe661743398..26368822a33f 100644
--- a/drivers/gpu/drm/i915/i915_suspend.c
+++ b/drivers/gpu/drm/i915/i915_suspend.c
@@ -303,6 +303,10 @@ int i915_save_state(struct drm_device *dev)
                 }
         }
 
+        if (IS_GEN4(dev))
+                pci_read_config_word(dev->pdev, GCDGMBUS,
+                                     &dev_priv->regfile.saveGCDGMBUS);
+
         /* Cache mode state */
         if (INTEL_INFO(dev)->gen < 7)
                 dev_priv->regfile.saveCACHE_MODE_0 = I915_READ(CACHE_MODE_0);
@@ -331,6 +335,10 @@ int i915_restore_state(struct drm_device *dev)
         mutex_lock(&dev->struct_mutex);
 
         i915_gem_restore_fences(dev);
+
+        if (IS_GEN4(dev))
+                pci_write_config_word(dev->pdev, GCDGMBUS,
+                                      dev_priv->regfile.saveGCDGMBUS);
         i915_restore_display(dev);
 
         if (!drm_core_check_feature(dev, DRIVER_MODESET)) {