gallium-docs: Add documentation for threading requirements

Add documentation for the requirements related to threading
for screens and contexts.

Signed-off-by: Axel Davy <axel.davy@ens.fr>
Reviewed-by: Marek Olšák <marek.olsak@amd.com>

diff --git a/src/gallium/docs/source/screen.rst b/src/gallium/docs/source/screen.rst
index 7ac39ffc44ff540cdf186bb1313d82788bc63d9f..86aa2591abef6923fe2f89e999905e12e7ebd966 100644 (file)
--- a/src/gallium/docs/source/screen.rst
+++ b/src/gallium/docs/source/screen.rst
@@ -737,3 +737,13 @@ query group at the specified **index** is returned in **info**.
 The function returns non-zero on success.
 The driver-specific query group is described with the
 pipe_driver_query_group_info structure.
+
+
+Thread safety
+-------------
+
+Screen methods are required to be thread safe. While gallium rendering
+contexts are not required to be thread safe, it is required to be safe to use
+different contexts created with the same screen in different threads without
+locks. It is also required to be safe using screen methods in a thread, while
+using one of its contexts in another (without locks).