drm/i915: Disable RC6 on Ironlake

The automatic powersaving feature is once again causing havoc, with 100%
reliable hangs on boot and resume on affected machines.

Reported-by: Francesco Allertsen <fallertsen@gmail.com>
Reported-by: Gui Rui <chaos.proton@gmail.com>
Bugzilla: https://bugzilla.kernel.org/show_bug.cgi?id=28582
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>

4 files changed, 55 insertions, 44 deletions

diff --git a/drivers/gpu/drm/i915/i915_drv.c b/drivers/gpu/drm/i915/i915_drv.c
index cfb56d0ff367..0ad533f06af9 100644
--- a/drivers/gpu/drm/i915/i915_drv.c
+++ b/drivers/gpu/drm/i915/i915_drv.c
@@ -46,6 +46,9 @@ module_param_named(fbpercrtc, i915_fbpercrtc, int, 0400);
 unsigned int i915_powersave = 1;
 module_param_named(powersave, i915_powersave, int, 0600);
 
+unsigned int i915_enable_rc6 = 0;
+module_param_named(i915_enable_rc6, i915_enable_rc6, int, 0600);
+
 unsigned int i915_lvds_downclock = 0;
 module_param_named(lvds_downclock, i915_lvds_downclock, int, 0400);
 
@@ -360,7 +363,7 @@ static int i915_drm_thaw(struct drm_device *dev)
                 /* Resume the modeset for every activated CRTC */
                 drm_helper_resume_force_mode(dev);
 
-                if (dev_priv->renderctx && dev_priv->pwrctx)
+                if (IS_IRONLAKE_M(dev))
                         ironlake_enable_rc6(dev);
         }
 
diff --git a/drivers/gpu/drm/i915/i915_drv.h b/drivers/gpu/drm/i915/i915_drv.h
index a0149c619cdd..65dfe81d0035 100644
--- a/drivers/gpu/drm/i915/i915_drv.h
+++ b/drivers/gpu/drm/i915/i915_drv.h
@@ -958,6 +958,7 @@ extern unsigned int i915_fbpercrtc;
 extern unsigned int i915_powersave;
 extern unsigned int i915_lvds_downclock;
 extern unsigned int i915_panel_use_ssc;
+extern unsigned int i915_enable_rc6;
 
 extern int i915_suspend(struct drm_device *dev, pm_message_t state);
 extern int i915_resume(struct drm_device *dev);
diff --git a/drivers/gpu/drm/i915/intel_display.c b/drivers/gpu/drm/i915/intel_display.c
index 7e42aa586504..94622e3a202e 100644
--- a/drivers/gpu/drm/i915/intel_display.c
+++ b/drivers/gpu/drm/i915/intel_display.c
@@ -6463,52 +6463,60 @@ void intel_enable_clock_gating(struct drm_device *dev)
         }
 }
 
-void intel_disable_clock_gating(struct drm_device *dev)
+static void ironlake_teardown_rc6(struct drm_device *dev)
 {
         struct drm_i915_private *dev_priv = dev->dev_private;
 
         if (dev_priv->renderctx) {
-                struct drm_i915_gem_object *obj = dev_priv->renderctx;
-
-                I915_WRITE(CCID, 0);
-                POSTING_READ(CCID);
-
-                i915_gem_object_unpin(obj);
-                drm_gem_object_unreference(&obj->base);
+                i915_gem_object_unpin(dev_priv->renderctx);
+                drm_gem_object_unreference(&dev_priv->renderctx->base);
                 dev_priv->renderctx = NULL;
         }
 
         if (dev_priv->pwrctx) {
-                struct drm_i915_gem_object *obj = dev_priv->pwrctx;
+                i915_gem_object_unpin(dev_priv->pwrctx);
+                drm_gem_object_unreference(&dev_priv->pwrctx->base);
+                dev_priv->pwrctx = NULL;
+        }
+}
+
+static void ironlake_disable_rc6(struct drm_device *dev)
+{
+        struct drm_i915_private *dev_priv = dev->dev_private;
+
+        if (I915_READ(PWRCTXA)) {
+                /* Wake the GPU, prevent RC6, then restore RSTDBYCTL */
+                I915_WRITE(RSTDBYCTL, I915_READ(RSTDBYCTL) | RCX_SW_EXIT);
+                wait_for(((I915_READ(RSTDBYCTL) & RSX_STATUS_MASK) == RSX_STATUS_ON),
+                         50);
 
                 I915_WRITE(PWRCTXA, 0);
                 POSTING_READ(PWRCTXA);
 
-                i915_gem_object_unpin(obj);
-                drm_gem_object_unreference(&obj->base);
-                dev_priv->pwrctx = NULL;
+                I915_WRITE(RSTDBYCTL, I915_READ(RSTDBYCTL) & ~RCX_SW_EXIT);
+                POSTING_READ(RSTDBYCTL);
         }
+
+        ironlake_disable_rc6(dev);
 }
 
-static void ironlake_disable_rc6(struct drm_device *dev)
+static int ironlake_setup_rc6(struct drm_device *dev)
 {
         struct drm_i915_private *dev_priv = dev->dev_private;
 
-        /* Wake the GPU, prevent RC6, then restore RSTDBYCTL */
-        I915_WRITE(RSTDBYCTL, I915_READ(RSTDBYCTL) | RCX_SW_EXIT);
-        wait_for(((I915_READ(RSTDBYCTL) & RSX_STATUS_MASK) == RSX_STATUS_ON),
-                 10);
-        POSTING_READ(CCID);
-        I915_WRITE(PWRCTXA, 0);
-        POSTING_READ(PWRCTXA);
-        I915_WRITE(RSTDBYCTL, I915_READ(RSTDBYCTL) & ~RCX_SW_EXIT);
-        POSTING_READ(RSTDBYCTL);
-        i915_gem_object_unpin(dev_priv->renderctx);
-        drm_gem_object_unreference(&dev_priv->renderctx->base);
-        dev_priv->renderctx = NULL;
-        i915_gem_object_unpin(dev_priv->pwrctx);
-        drm_gem_object_unreference(&dev_priv->pwrctx->base);
-        dev_priv->pwrctx = NULL;
+        if (dev_priv->renderctx == NULL)
+                dev_priv->renderctx = intel_alloc_context_page(dev);
+        if (!dev_priv->renderctx)
+                return -ENOMEM;
+
+        if (dev_priv->pwrctx == NULL)
+                dev_priv->pwrctx = intel_alloc_context_page(dev);
+        if (!dev_priv->pwrctx) {
+                ironlake_teardown_rc6(dev);
+                return -ENOMEM;
+        }
+
+        return 0;
 }
 
 void ironlake_enable_rc6(struct drm_device *dev)
@@ -6516,15 +6524,26 @@ void ironlake_enable_rc6(struct drm_device *dev)
         struct drm_i915_private *dev_priv = dev->dev_private;
         int ret;
 
+        /* rc6 disabled by default due to repeated reports of hanging during
+         * boot and resume.
+         */
+        if (!i915_enable_rc6)
+                return;
+
+        ret = ironlake_setup_rc6(dev);
+        if (ret)
+                return;
+
         /*
          * GPU can automatically power down the render unit if given a page
          * to save state.
          */
         ret = BEGIN_LP_RING(6);
         if (ret) {
-                ironlake_disable_rc6(dev);
+                ironlake_teardown_rc6(dev);
                 return;
         }
+
         OUT_RING(MI_SUSPEND_FLUSH | MI_SUSPEND_FLUSH_EN);
         OUT_RING(MI_SET_CONTEXT);
         OUT_RING(dev_priv->renderctx->gtt_offset |
@@ -6541,6 +6560,7 @@ void ironlake_enable_rc6(struct drm_device *dev)
         I915_WRITE(RSTDBYCTL, I915_READ(RSTDBYCTL) & ~RCX_SW_EXIT);
 }
 
+
 /* Set up chip specific display functions */
 static void intel_init_display(struct drm_device *dev)
 {
@@ -6783,21 +6803,9 @@ void intel_modeset_init(struct drm_device *dev)
         if (IS_GEN6(dev))
                 gen6_enable_rps(dev_priv);
 
-        if (IS_IRONLAKE_M(dev)) {
-                dev_priv->renderctx = intel_alloc_context_page(dev);
-                if (!dev_priv->renderctx)
-                        goto skip_rc6;
-                dev_priv->pwrctx = intel_alloc_context_page(dev);
-                if (!dev_priv->pwrctx) {
-                        i915_gem_object_unpin(dev_priv->renderctx);
-                        drm_gem_object_unreference(&dev_priv->renderctx->base);
-                        dev_priv->renderctx = NULL;
-                        goto skip_rc6;
-                }
+        if (IS_IRONLAKE_M(dev))
                 ironlake_enable_rc6(dev);
-        }
 
-skip_rc6:
         INIT_WORK(&dev_priv->idle_work, intel_idle_update);
         setup_timer(&dev_priv->idle_timer, intel_gpu_idle_timer,
                     (unsigned long)dev);
diff --git a/drivers/gpu/drm/i915/intel_drv.h b/drivers/gpu/drm/i915/intel_drv.h
index 74db2557d644..2c431049963c 100644
--- a/drivers/gpu/drm/i915/intel_drv.h
+++ b/drivers/gpu/drm/i915/intel_drv.h
@@ -298,7 +298,6 @@ extern void intel_crtc_fb_gamma_set(struct drm_crtc *crtc, u16 red, u16 green,
 extern void intel_crtc_fb_gamma_get(struct drm_crtc *crtc, u16 *red, u16 *green,
                                     u16 *blue, int regno);
 extern void intel_enable_clock_gating(struct drm_device *dev);
-extern void intel_disable_clock_gating(struct drm_device *dev);
 extern void ironlake_enable_drps(struct drm_device *dev);
 extern void ironlake_disable_drps(struct drm_device *dev);
 extern void gen6_enable_rps(struct drm_i915_private *dev_priv);