drm/i915: Flush logical context image out to memory upon suspend
authorChris Wilson <chris@chris-wilson.co.uk>
Fri, 15 Jul 2016 13:56:20 +0000 (14:56 +0100)
committerChris Wilson <chris@chris-wilson.co.uk>
Fri, 15 Jul 2016 19:41:05 +0000 (20:41 +0100)
Before suspend, and especially before building the hibernation image, we
need to context image to be coherent in memory. To do this we require
that we perform a context switch to a disposable context (i.e. the
dev_priv->kernel_context) - when that switch is complete, all other
context images will be complete. This leaves the kernel_context image as
incomplete, but fortunately that is disposable and we can do a quick
fixup of the logical state after resuming.

v2: Share the nearly identical code to switch to the kernel context with
eviction.
v3: Explain why we need the switch and reset.

Testcase: igt/gem_exec_suspend # bsw
References: https://bugs.freedesktop.org/show_bug.cgi?id=96526
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Ville Syrjälä <ville.syrjala@linux.intel.com>
Reviewed-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Tested-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/1468590980-6186-2-git-send-email-chris@chris-wilson.co.uk
drivers/gpu/drm/i915/i915_drv.c
drivers/gpu/drm/i915/i915_drv.h
drivers/gpu/drm/i915/i915_gem.c

index 15440123e38d221c5671c4198b7e0558fae7722a..c5b7b8e0678a354d2a529c53d33c128d722f39c7 100644 (file)
@@ -1590,9 +1590,7 @@ static int i915_drm_resume(struct drm_device *dev)
 
        intel_csr_ucode_resume(dev_priv);
 
-       mutex_lock(&dev->struct_mutex);
-       i915_gem_restore_gtt_mappings(dev);
-       mutex_unlock(&dev->struct_mutex);
+       i915_gem_resume(dev);
 
        i915_restore_state(dev);
        intel_opregion_setup(dev_priv);
index cd1ccc47ee8b3133e0c77e64f9e6f7066c9092ae..27d9b2c374b370fbc8b0bda67f1ab220c337c3a0 100644 (file)
@@ -3384,6 +3384,7 @@ void i915_gem_init_swizzling(struct drm_device *dev);
 void i915_gem_cleanup_engines(struct drm_device *dev);
 int __must_check i915_gem_wait_for_idle(struct drm_i915_private *dev_priv);
 int __must_check i915_gem_suspend(struct drm_device *dev);
+void i915_gem_resume(struct drm_device *dev);
 void __i915_add_request(struct drm_i915_gem_request *req,
                        struct drm_i915_gem_object *batch_obj,
                        bool flush_caches);
index cf0e8aa8035c045140b53aff02c508df647b3dac..4644a7e67cf6bae4fb8c5b2e84ff7962bf17f5f0 100644 (file)
@@ -4983,12 +4983,30 @@ i915_gem_suspend(struct drm_device *dev)
        intel_suspend_gt_powersave(dev_priv);
 
        mutex_lock(&dev->struct_mutex);
+
+       /* We have to flush all the executing contexts to main memory so
+        * that they can saved in the hibernation image. To ensure the last
+        * context image is coherent, we have to switch away from it. That
+        * leaves the dev_priv->kernel_context still active when
+        * we actually suspend, and its image in memory may not match the GPU
+        * state. Fortunately, the kernel_context is disposable and we do
+        * not rely on its state.
+        */
+       ret = i915_gem_switch_to_kernel_context(dev_priv);
+       if (ret)
+               goto err;
+
        ret = i915_gem_wait_for_idle(dev_priv);
        if (ret)
                goto err;
 
        i915_gem_retire_requests(dev_priv);
 
+       /* Note that rather than stopping the engines, all we have to do
+        * is assert that every RING_HEAD == RING_TAIL (all execution complete)
+        * and similar for all logical context images (to ensure they are
+        * all ready for hibernation).
+        */
        i915_gem_stop_engines(dev);
        i915_gem_context_lost(dev_priv);
        mutex_unlock(&dev->struct_mutex);
@@ -5009,6 +5027,23 @@ err:
        return ret;
 }
 
+void i915_gem_resume(struct drm_device *dev)
+{
+       struct drm_i915_private *dev_priv = to_i915(dev);
+
+       mutex_lock(&dev->struct_mutex);
+       i915_gem_restore_gtt_mappings(dev);
+
+       /* As we didn't flush the kernel context before suspend, we cannot
+        * guarantee that the context image is complete. So let's just reset
+        * it and start again.
+        */
+       if (i915.enable_execlists)
+               intel_lr_context_reset(dev_priv, dev_priv->kernel_context);
+
+       mutex_unlock(&dev->struct_mutex);
+}
+
 void i915_gem_init_swizzling(struct drm_device *dev)
 {
        struct drm_i915_private *dev_priv = to_i915(dev);