wayland_protocols::wp::linux_dmabuf::zv1::client

Module zwp_linux_dmabuf_v1

Source
Available on crate feature client only.
Expand description

factory for creating dmabuf-based wl_buffers

This interface offers ways to create generic dmabuf-based wl_buffers.

For more information about dmabuf, see: https://www.kernel.org/doc/html/next/userspace-api/dma-buf-alloc-exchange.html

Clients can use the get_surface_feedback request to get dmabuf feedback for a particular surface. If the client wants to retrieve feedback not tied to a surface, they can use the get_default_feedback request.

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.

However, when the underlying graphics stack fails to deliver the promise, because of e.g. a device hot-unplug which raises internal errors, after the wl_buffer has been successfully created the compositor must not raise protocol errors to the client when dmabuf import later fails.

To create a wl_buffer from one or more dmabufs, a client creates a zwp_linux_dmabuf_params_v1 object with a zwp_linux_dmabuf_v1.create_params request. All planes required by the intended format are added with the ‘add’ request. Finally, a ‘create’ or ‘create_immed’ request is issued, which has the following outcome depending on the import success.

The ‘create’ request,

  • on success, triggers a ‘created’ event which provides the final wl_buffer to the client.
  • on failure, triggers a ‘failed’ event to convey that the server cannot use the dmabufs received from the client.

For the ‘create_immed’ request,

  • on success, the server immediately imports the added dmabufs to create a wl_buffer. No event is sent from the server in this case.
  • on failure, the server can choose to either:
  • terminate the client by raising a fatal error.
  • mark the wl_buffer as failed, and send a ‘failed’ event to the client. If the client uses a failed wl_buffer as an argument to any request, the behaviour is compositor implementation-defined.

For all DRM formats and unless specified in another protocol extension, pre-multiplied alpha is used for pixel values.

Unless specified otherwise in another protocol extension, implicit synchronization is used. In other words, compositors and clients must wait and signal fences implicitly passed via the DMA-BUF’s reservation mechanism.

Structs§

ZwpLinuxDmabufV1
factory for creating dmabuf-based wl_buffers

Enums§

Event
Request

Constants§

EVT_FORMAT_OPCODE
The wire opcode for this event
EVT_FORMAT_SINCE
The minimal object version supporting this event
EVT_MODIFIER_OPCODE
The wire opcode for this event
EVT_MODIFIER_SINCE
The minimal object version supporting this event
REQ_CREATE_PARAMS_OPCODE
The wire opcode for this request
REQ_CREATE_PARAMS_SINCE
The minimal object version supporting this request
REQ_DESTROY_OPCODE
The wire opcode for this request
REQ_DESTROY_SINCE
The minimal object version supporting this request
REQ_GET_DEFAULT_FEEDBACK_OPCODE
The wire opcode for this request
REQ_GET_DEFAULT_FEEDBACK_SINCE
The minimal object version supporting this request
REQ_GET_SURFACE_FEEDBACK_OPCODE
The wire opcode for this request
REQ_GET_SURFACE_FEEDBACK_SINCE
The minimal object version supporting this request