drm: add flip-work helper

A small helper to queue up work to do, from workqueue context, after a
flip.  Typically useful to defer unreffing buffers that may be read by
the display controller until vblank.

v1: original
v2: wire up docbook + couple docbook fixes

Signed-off-by: Rob Clark <robdclark@gmail.com>
Acked-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Signed-off-by: Dave Airlie <airlied@redhat.com>

1 files changed, 76 insertions, 0 deletions

diff --git a/include/drm/drm_flip_work.h b/include/drm/drm_flip_work.h
new file mode 100644
index 000000000000..35c776ae7d3b
--- /dev/null
+++ b/include/drm/drm_flip_work.h
@@ -0,0 +1,76 @@
+/*
+ * Copyright (C) 2013 Red Hat
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a
+ * copy of this software and associated documentation files (the "Software"),
+ * to deal in the Software without restriction, including without limitation
+ * the rights to use, copy, modify, merge, publish, distribute, sublicense,
+ * and/or sell copies of the Software, and to permit persons to whom the
+ * Software is furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice (including the next
+ * paragraph) shall be included in all copies or substantial portions of the
+ * Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL
+ * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+ * SOFTWARE.
+ */
+
+#ifndef DRM_FLIP_WORK_H
+#define DRM_FLIP_WORK_H
+
+#include <linux/kfifo.h>
+#include <linux/workqueue.h>
+
+/**
+ * DOC: flip utils
+ *
+ * Util to queue up work to run from work-queue context after flip/vblank.
+ * Typically this can be used to defer unref of framebuffer's, cursor
+ * bo's, etc until after vblank.  The APIs are all safe (and lockless)
+ * for up to one producer and once consumer at a time.  The single-consumer
+ * aspect is ensured by committing the queued work to a single work-queue.
+ */
+
+struct drm_flip_work;
+
+/*
+ * drm_flip_func_t - callback function
+ *
+ * @work: the flip work
+ * @val: value queued via drm_flip_work_queue()
+ *
+ * Callback function to be called for each of the  queue'd work items after
+ * drm_flip_work_commit() is called.
+ */
+typedef void (*drm_flip_func_t)(struct drm_flip_work *work, void *val);
+
+/**
+ * struct drm_flip_work - flip work queue
+ * @name: debug name
+ * @pending: number of queued but not committed items
+ * @count: number of committed items
+ * @func: callback fxn called for each committed item
+ * @worker: worker which calls @func
+ */
+struct drm_flip_work {
+	const char *name;
+	atomic_t pending, count;
+	drm_flip_func_t func;
+	struct work_struct worker;
+	DECLARE_KFIFO_PTR(fifo, void *);
+};
+
+void drm_flip_work_queue(struct drm_flip_work *work, void *val);
+void drm_flip_work_commit(struct drm_flip_work *work,
+		struct workqueue_struct *wq);
+int drm_flip_work_init(struct drm_flip_work *work, int size,
+		const char *name, drm_flip_func_t func);
+void drm_flip_work_cleanup(struct drm_flip_work *work);
+
+#endif  /* DRM_FLIP_WORK_H */