drm/i915: Adapt workqueue to new alloc_workqueue interface

create_singlethreaded_workqueue() is being phased out for a new
concurrency managed task infrastructure.

Adapt our workqueue constructor to explicitly create a domain that only
allows the execution of a single task at any time. All the tasks are
expected to require the dev->struct_mutex, so would block concurrency of
other tasks if we allow more than a single i915 task to be run at once.

Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>

diff --git a/drivers/gpu/drm/i915/i915_dma.c b/drivers/gpu/drm/i915/i915_dma.c
index 428c75b..7c7d1bc 100644 (file)
--- a/drivers/gpu/drm/i915/i915_dma.c
+++ b/drivers/gpu/drm/i915/i915_dma.c
@@ -1951,7 +1951,22 @@ int i915_driver_load(struct drm_device *dev, unsigned long flags)
        prealloc_size = dev_priv->mm.gtt->gtt_stolen_entries << PAGE_SHIFT;
        agp_size = dev_priv->mm.gtt->gtt_mappable_entries << PAGE_SHIFT;
 
-       dev_priv->wq = create_singlethread_workqueue("i915");
+       /* The i915 workqueue is primarily used for batched retirement of
+        * requests (and thus managing bo) once the task has been completed
+        * by the GPU. i915_gem_retire_requests() is called directly when we
+        * need high-priority retirement, such as waiting for an explicit
+        * bo.
+        *
+        * It is also used for periodic low-priority events, such as
+        * idle-timers and hangcheck.
+        *
+        * All tasks on the workqueue are expected to acquire the dev mutex
+        * so there is no point in running more than one instance of the
+        * workqueue at any time: max_active = 1 and NON_REENTRANT.
+        */
+       dev_priv->wq = alloc_workqueue("i915",
+                                      WQ_UNBOUND | WQ_NON_REENTRANT,
+                                      1);
        if (dev_priv->wq == NULL) {
                DRM_ERROR("Failed to create our workqueue.\n");
                ret = -ENOMEM;