drm/fence: add fence timeline to drm_crtc

Create one timeline context for each CRTC to be able to handle out-fences
and signal them. It adds a few members to struct drm_crtc: fence_context,
where we store the context we get from fence_context_alloc(), the
fence seqno and the fence lock, that we pass in fence_init() to be
used by the fence.

v2: Comment by Daniel Stone:
	- add BUG_ON() to fence_to_crtc() macro

v3: Comment by Ville Syrjälä
	- Use more meaningful name as crtc timeline name

v4: Comments by Brian Starkey
	- Use even more meaninful name for the crtc timeline
	- add doc for timeline_name
    Comment by Daniel Vetter
	- use in-line style for comments

    - rebase after fence -> dma_fence rename

v5: Comment by Daniel Vetter
	- Add doc for drm_crtc_fence_ops

v6: Comment by Chris Wilson
	- Move fence_to_crtc to drm_crtc.c
	- Move export of drm_crtc_fence_ops to drm_crtc_internal.h

    - rebase against latest drm-misc

Signed-off-by: Gustavo Padovan <gustavo.padovan@collabora.co.uk>
Reviewed-by: Daniel Vetter <daniel.vetter@ffwll.ch> (v5)
Reviewed-by: Sean Paul <seanpaul@chromium.org> (v5)
Tested-by: Robert Foss <robert.foss@collabora.com> (v5)
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Link: http://patchwork.freedesktop.org/patch/msgid/1479220628-10204-1-git-send-email-gustavo@padovan.org

drivers/gpu/drm/drm_crtc.c

@@ -33,6 +33,7 @@
 #include <linux/list.h>
 #include <linux/slab.h>
 #include <linux/export.h>
+#include <linux/dma-fence.h>
 #include <drm/drmP.h>
 #include <drm/drm_crtc.h>
 #include <drm/drm_edid.h>
@@ -151,6 +152,38 @@ static void drm_crtc_crc_fini(struct drm_crtc *crtc)
 #endif
 }
 
+static struct drm_crtc *fence_to_crtc(struct dma_fence *fence)
+{
+	BUG_ON(fence->ops != &drm_crtc_fence_ops);
+	return container_of(fence->lock, struct drm_crtc, fence_lock);
+}
+
+static const char *drm_crtc_fence_get_driver_name(struct dma_fence *fence)
+{
+	struct drm_crtc *crtc = fence_to_crtc(fence);
+
+	return crtc->dev->driver->name;
+}
+
+static const char *drm_crtc_fence_get_timeline_name(struct dma_fence *fence)
+{
+	struct drm_crtc *crtc = fence_to_crtc(fence);
+
+	return crtc->timeline_name;
+}
+
+static bool drm_crtc_fence_enable_signaling(struct dma_fence *fence)
+{
+	return true;
+}
+
+const struct dma_fence_ops drm_crtc_fence_ops = {
+	.get_driver_name = drm_crtc_fence_get_driver_name,
+	.get_timeline_name = drm_crtc_fence_get_timeline_name,
+	.enable_signaling = drm_crtc_fence_enable_signaling,
+	.wait = dma_fence_default_wait,
+};
+
 /**
  * drm_crtc_init_with_planes - Initialise a new CRTC object with
  *    specified primary and cursor planes.
@@ -208,6 +241,11 @@ int drm_crtc_init_with_planes(struct drm_device *dev, struct drm_crtc *crtc,
 		return -ENOMEM;
 	}
 
+	crtc->fence_context = dma_fence_context_alloc(1);
+	spin_lock_init(&crtc->fence_lock);
+	snprintf(crtc->timeline_name, sizeof(crtc->timeline_name),
+		 "CRTC:%d-%s", crtc->base.id, crtc->name);
+
 	crtc->base.properties = &crtc->properties;
 
 	list_add_tail(&crtc->head, &config->crtc_list);

drivers/gpu/drm/drm_crtc_internal.h

@@ -43,6 +43,8 @@ int drm_crtc_check_viewport(const struct drm_crtc *crtc,
 int drm_crtc_register_all(struct drm_device *dev);
 void drm_crtc_unregister_all(struct drm_device *dev);
 
+extern const struct dma_fence_ops drm_crtc_fence_ops;
+
 /* IOCTLs */
 int drm_mode_getcrtc(struct drm_device *dev,
 		     void *data, struct drm_file *file_priv);

include/drm/drm_crtc.h

@@ -731,6 +731,35 @@ struct drm_crtc {
 	 */
 	struct drm_crtc_crc crc;
 #endif
+
+	/**
+	 * @fence_context:
+	 *
+	 * timeline context used for fence operations.
+	 */
+	unsigned int fence_context;
+
+	/**
+	 * @fence_lock:
+	 *
+	 * spinlock to protect the fences in the fence_context.
+	 */
+
+	spinlock_t fence_lock;
+	/**
+	 * @fence_seqno:
+	 *
+	 * Seqno variable used as monotonic counter for the fences
+	 * created on the CRTC's timeline.
+	 */
+	unsigned long fence_seqno;
+
+	/**
+	 * @timeline_name:
+	 *
+	 * The name of the CRTC's fence timeline.
+	 */
+	char timeline_name[32];
 };
 
 /**