gallium: add fence_server_signal() v2
Calling this function will emit a fence signal operation into the GPU's command stream. v2: documentation typos Signed-off-by: Andres Rodriguez <andresx7@gmail.com> Reviewed-by: Marek Olšák <marek.olsak@amd.com>
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@ -567,7 +567,38 @@ by a single pipe_screen and is not shared with another process.
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(i.e. you shouldn't use it to flush caches explicitly if you want to e.g.
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use the resource for texturing)
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Fences
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^^^^^^
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``pipe_fence_handle``, and related methods, are used to synchronize
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execution between multiple parties. Examples include CPU <-> GPU synchronization,
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renderer <-> windowing system, multiple external APIs, etc.
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A ``pipe_fence_handle`` can either be 'one time use' or 're-usable'. A 'one time use'
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fence behaves like a traditional GPU fence. Once it reaches the signaled state it
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is forever considered to be signaled.
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Once a re-usable ``pipe_fence_handle`` becomes signaled, it can be reset
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back into an unsignaled state. The ``pipe_fence_handle`` will be reset to
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the unsignaled state by performing a wait operation on said object, i.e.
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``fence_server_sync``. As a corollary to this behaviour, a re-usable
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``pipe_fence_handle`` can only have one waiter.
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This behaviour is useful in producer <-> consumer chains. It helps avoid
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unecessarily sharing a new ``pipe_fence_handle`` each time a new frame is
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ready. Instead, the fences are exchanged once ahead of time, and access is synchronized
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through GPU signaling instead of direct producer <-> consumer communication.
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``fence_server_sync`` inserts a wait command into the GPU's command stream.
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``fence_server_signal`` inserts a signal command into the GPU's command stream.
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There are no guarantees that the wait/signal commands will be flushed when
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calling ``fence_server_sync`` or ``fence_server_signal``. An explicit
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call to ``flush`` is required to make sure the commands are emitted to the GPU.
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The Gallium implementation may implicitly ``flush`` the command stream during a
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``fence_server_sync`` or ``fence_server_signal`` call if necessary.
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Resource Busy Queries
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^^^^^^^^^^^^^^^^^^^^^
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@ -525,6 +525,12 @@ struct pipe_context {
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void (*fence_server_sync)(struct pipe_context *pipe,
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struct pipe_fence_handle *fence);
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/**
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* Insert commands to have the GPU signal a fence.
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*/
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void (*fence_server_signal)(struct pipe_context *pipe,
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struct pipe_fence_handle *fence);
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/**
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* Create a view on a texture to be used by a shader stage.
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*/
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