gallium: Basic compute interface.

Define an interface that exposes the minimal functionality required to
implement some of the popular compute APIs.  This commit adds entry
points to set the grid layout and other state required to keep track
of the usual address spaces employed in compute APIs, to bind a
compute program, and execute it on the device.

Reviewed-by: Marek Olšák <[email protected]>

1 files changed, 39 insertions, 0 deletions

diff --git a/src/gallium/docs/source/context.rst b/src/gallium/docs/source/context.rst
index b2872cd282f..cb9b8de7d5a 100644
--- a/src/gallium/docs/source/context.rst
+++ b/src/gallium/docs/source/context.rst
@@ -542,3 +542,42 @@ These flags control the behavior of a transfer object.
 ``PIPE_TRANSFER_FLUSH_EXPLICIT``
   Written ranges will be notified later with :ref:`transfer_flush_region`.
   Cannot be used with ``PIPE_TRANSFER_READ``.
+
+
+Compute kernel execution
+^^^^^^^^^^^^^^^^^^^^^^^^
+
+A compute program can be defined, bound or destroyed using
+``create_compute_state``, ``bind_compute_state`` or
+``destroy_compute_state`` respectively.
+
+Any of the subroutines contained within the compute program can be
+executed on the device using the ``launch_grid`` method.  This method
+will execute as many instances of the program as elements in the
+specified N-dimensional grid, hopefully in parallel.
+
+The compute program has access to four special resources:
+
+* ``GLOBAL`` represents a memory space shared among all the threads
+  running on the device.  An arbitrary buffer created with the
+  ``PIPE_BIND_GLOBAL`` flag can be mapped into it using the
+  ``set_global_binding`` method.
+
+* ``LOCAL`` represents a memory space shared among all the threads
+  running in the same working group.  The initial contents of this
+  resource are undefined.
+
+* ``PRIVATE`` represents a memory space local to a single thread.
+  The initial contents of this resource are undefined.
+
+* ``INPUT`` represents a read-only memory space that can be
+  initialized at ``launch_grid`` time.
+
+These resources use a byte-based addressing scheme, and they can be
+accessed from the compute program by means of the LOAD/STORE TGSI
+opcodes.
+
+In addition, normal texture sampling is allowed from the compute
+program: ``bind_compute_sampler_states`` may be used to set up texture
+samplers for the compute stage and ``set_compute_sampler_views`` may
+be used to bind a number of sampler views to it.