drm/vgem: Attach sw fences to exported vGEM dma-buf (ioctl)

vGEM buffers are useful for passing data between software clients and
hardware renders. By allowing the user to create and attach fences to
the exported vGEM buffers (on the dma-buf), the user can implement a
deferred renderer and queue hardware operations like flipping and then
signal the buffer readiness (i.e. this allows the user to schedule
operations out-of-order, but have them complete in-order).

This also makes it much easier to write tightly controlled testcases for
dma-buf fencing and signaling between hardware drivers.

v2: Don't pretend the fences exist in an ordered timeline, but allocate
a separate fence-context for each fence so that the fences are
unordered.
v3: Make the debug output more interesting, and show the signaled status.
v4: Automatically signal the fence to prevent userspace from
indefinitely hanging drivers.

Testcase: igt/vgem_basic/dmabuf-fence
Testcase: igt/vgem_slow/nohang
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Sean Paul <seanpaul@chromium.org>
Cc: Zach Reizner <zachr@google.com>
Cc: Gustavo Padovan <gustavo.padovan@collabora.co.uk>
Cc: Daniel Vetter <daniel.vetter@ffwll.ch>
Acked-by: Zach Reizner <zachr@google.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Link: http://patchwork.freedesktop.org/patch/msgid/1468571471-12610-1-git-send-email-chris@chris-wilson.co.uk

1 files changed, 62 insertions, 0 deletions

diff --git a/include/uapi/drm/vgem_drm.h b/include/uapi/drm/vgem_drm.h
new file mode 100644
index 000000000000..bf66f5db6da8
--- /dev/null
+++ b/include/uapi/drm/vgem_drm.h
@@ -0,0 +1,62 @@
+/*
+ * Copyright 2016 Intel Corporation
+ * All Rights Reserved.
+ *
+ * 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, sub license, 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 NON-INFRINGEMENT.
+ * IN NO EVENT SHALL TUNGSTEN GRAPHICS AND/OR ITS SUPPLIERS 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 _UAPI_VGEM_DRM_H_
+#define _UAPI_VGEM_DRM_H_
+
+#include "drm.h"
+
+#if defined(__cplusplus)
+extern "C" {
+#endif
+
+/* Please note that modifications to all structs defined here are
+ * subject to backwards-compatibility constraints.
+ */
+#define DRM_VGEM_FENCE_ATTACH	0x1
+#define DRM_VGEM_FENCE_SIGNAL	0x2
+
+#define DRM_IOCTL_VGEM_FENCE_ATTACH	DRM_IOWR( DRM_COMMAND_BASE + DRM_VGEM_FENCE_ATTACH, struct drm_vgem_fence_attach)
+#define DRM_IOCTL_VGEM_FENCE_SIGNAL	DRM_IOW( DRM_COMMAND_BASE + DRM_VGEM_FENCE_SIGNAL, struct drm_vgem_fence_signal)
+
+struct drm_vgem_fence_attach {
+	__u32 handle;
+	__u32 flags;
+#define VGEM_FENCE_WRITE	0x1
+	__u32 out_fence;
+	__u32 pad;
+};
+
+struct drm_vgem_fence_signal {
+	__u32 fence;
+	__u32 flags;
+};
+
+#if defined(__cplusplus)
+}
+#endif
+
+#endif /* _UAPI_VGEM_DRM_H_ */