Copyright © 2014, 2015 Collabora, Ltd. Permission to use, copy, modify, distribute, and sell this software and its documentation for any purpose is hereby granted without fee, provided that the above copyright notice appear in all copies and that both that copyright notice and this permission notice appear in supporting documentation, and that the name of the copyright holders not be used in advertising or publicity pertaining to distribution of the software without specific, written prior permission. The copyright holders make no representations about the suitability of this software for any purpose. It is provided "as is" without express or implied warranty. THE COPYRIGHT HOLDERS DISCLAIM ALL WARRANTIES WITH REGARD TO THIS SOFTWARE, INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS, IN NO EVENT SHALL THE COPYRIGHT HOLDERS BE LIABLE FOR ANY SPECIAL, INDIRECT OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE. Following the interfaces from: https://www.khronos.org/registry/egl/extensions/EXT/EGL_EXT_image_dma_buf_import.txt and the Linux DRM sub-system's AddFb2 ioctl. This interface offers a way to create generic dmabuf-based wl_buffers. Immediately after a client binds to this interface, the set of supported formats is sent with 'format' events. The following are required from clients: - Clients must ensure that either all data in the dma-buf is coherent for all subsequent read access or that coherency is correctly handled by the underlying kernel-side dma-buf implementation. - Don't make any more attachments after sending the buffer to the compositor. Making more attachments later increases the risk of the compositor not being able to use (re-import) an existing dmabuf-based wl_buffer. The underlying graphics stack must ensure the following: - The dmabuf file descriptors relayed to the server will stay valid for the whole lifetime of the wl_buffer. This means the server may at any time use those fds to import the dmabuf into any kernel sub-system that might accept it. To create a wl_buffer from one or more dmabufs, a client creates a zlinux_dmabuf_params object with zlinux_dmabuf.create_params request. All planes required by the intended format are added with the 'add' request. Finally, 'create' request is issued. The server will reply with either 'created' event which provides the final wl_buffer or 'failed' event saying that it cannot use the dmabufs provided. Objects created through this interface, especially wl_buffers, will remain valid. This temporary object is used to collect multiple dmabuf handles into a single batch to create a wl_buffer. It can only be used once and should be destroyed after an 'created' or 'failed' event has been received. This event advertises one buffer format that the server supports. All the supported formats are advertised once when the client binds to this interface. A roundtrip after binding guarantees, that the client has received all supported formats. For the definition of the format codes, see create request. XXX: Can a compositor ever enumerate them? This temporary object is a collection of dmabufs and other parameters that together form a single logical buffer. The temporary object may eventually create one wl_buffer unless cancelled by destroying it before requesting 'create'. Single-planar formats only require one dmabuf, however multi-planar formats may require more than one dmabuf. For all formats, 'add' request must be called once per plane (even if the underlying dmabuf fd is identical). You must use consecutive plane indices ('plane_idx' argument for 'add') from zero to the number of planes used by the drm_fourcc format code. All planes required by the format must be given exactly once, but can be given in any order. Each plane index can be set only once. Cleans up the temporary data sent to the server for dmabuf-based wl_buffer creation. This request adds one dmabuf to the set in this zlinux_buffer_params. The 64-bit unsigned value combined from modifier_hi and modifier_lo is the dmabuf layout modifier. DRM AddFB2 ioctl calls this the fb modifier, which is defined in drm_mode.h of Linux UAPI. This is an opaque token. Drivers use this token to express tiling, compression, etc. driver-specific modifications to the base format defined by the DRM fourcc code. This request raises the PLANE_IDX error if plane_idx is too large. The error PLANE_SET is raised if attempting to set a plane that was already set. This asks for creation of a wl_buffer from the added dmabuf buffers. The wl_buffer is not created immediately but returned via the 'created' event if the dmabuf sharing succeeds. The sharing may fail at runtime for reasons a client cannot predict, in which case the 'failed' event is triggered. The 'format' argument is a DRM_FORMAT code, as defined by the libdrm's drm_fourcc.h. The Linux kernel's DRM sub-system is the authoritative source on how the format codes should work. The 'flags' is a bitfield of the flags defined in enum "flags". 'y_invert' means the that the image needs to be y-flipped. Flag 'interlaced' means that the frame in the buffer is not progressive as usual, but interlaced. An interlaced buffer as supported here must always contain both top and bottom fields. The top field always begins on the first pixel row. The temporal ordering between the two fields is top field first, unless 'bottom_first' is specified. It is undefined whether 'bottom_first' is ignored if 'interlaced' is not set. This protocol does not convey any information about field rate, duration, or timing, other than the relative ordering between the two fields in one buffer. A compositor may have to estimate the intended field rate from the incoming buffer rate. It is undefined whether the time of receiving wl_surface.commit with a new buffer attached, applying the wl_surface state, wl_surface.frame callback trigger, presentation, or any other point in the compositor cycle is used to measure the frame or field times. There is no support for detecting missed or late frames/fields/buffers either, and there is no support whatsoever for cooperating with interlaced compositor output. The composited image quality resulting from the use of interlaced buffers is explicitly undefined. A compositor may use elaborate hardware features or software to deinterlace and create progressive output frames from a sequence of interlaced input buffers, or it may produce substandard image quality. However, compositors that cannot guarantee reasonable image quality in all cases are recommended to just reject all interlaced buffers. Any argument errors, including non-positive width or height, mismatch between the number of planes and the format, bad format, bad offset or stride, may be indicated by fatal protocol errors: INCOMPLETE, INVALID_FORMAT, INVALID_DIMENSIONS, OUT_OF_BOUNDS. Dmabuf import errors in the server that are not obvious client bugs are returned via the 'failed' event as non-fatal. This allows attempting dmabuf sharing and falling back in the client if it fails. This request can be sent only once in the object's lifetime, after which the only legal request is destroy. This object should be destroyed after issuing 'create' request. Attempting to use this object after issuing 'create' raises ALREADY_USED protocol error. It is not mandatory to issue 'create'. If a client wants to cancel the buffer creation, it can just destroy this object. This event indicates that the attempted buffer creation was successful. It provides the new wl_buffer referencing the dmabuf(s). Upon receiving this event, the client should destroy the zlinux_dmabuf_params object. This event indicates that the attempted buffer creation has failed. It usually means that one of the dmabuf constraints has not been fulfilled. Upon receiving this event, the client should destroy the zlinux_buffer_params object.