drm/i915/hsw: Fix GPU hang during resume from S3-devices state

[karo-tx-linux.git] / drivers / gpu / drm / i915 / i915_gem.c

diff --git a/drivers/gpu/drm/i915/i915_gem.c b/drivers/gpu/drm/i915/i915_gem.c
index fdd496e6c081ca2d8bda6632e427f5cbdf861b66..830df36ca14cea69f25f3f8789c0dd586ee95fbf 100644 (file)
--- a/drivers/gpu/drm/i915/i915_gem.c
+++ b/drivers/gpu/drm/i915/i915_gem.c
@@ -4273,6 +4273,30 @@ int i915_gem_suspend(struct drm_device *dev)
         */
        WARN_ON(dev_priv->gt.awake);
 
+       /*
+        * Neither the BIOS, ourselves or any other kernel
+        * expects the system to be in execlists mode on startup,
+        * so we need to reset the GPU back to legacy mode. And the only
+        * known way to disable logical contexts is through a GPU reset.
+        *
+        * So in order to leave the system in a known default configuration,
+        * always reset the GPU upon unload and suspend. Afterwards we then
+        * clean up the GEM state tracking, flushing off the requests and
+        * leaving the system in a known idle state.
+        *
+        * Note that is of the upmost importance that the GPU is idle and
+        * all stray writes are flushed *before* we dismantle the backing
+        * storage for the pinned objects.
+        *
+        * However, since we are uncertain that resetting the GPU on older
+        * machines is a good idea, we don't - just in case it leaves the
+        * machine in an unusable condition.
+        */
+       if (HAS_HW_CONTEXTS(dev)) {
+               int reset = intel_gpu_reset(dev_priv, ALL_ENGINES);
+               WARN_ON(reset && reset != -ENODEV);
+       }
+
        return 0;
 
 err: