Previously, no buffers were ever marked as EXEC_OBJECT_ASYNC so the
Kernel would ensure dependency tracking for us. After we implemented
explicit busy tracking in commit 89a34cb845, only the external
objects kept relying on the Kernel's implicit tracking and Iris did
inter-batch busy tracking, meaning we lost inter-screen and
inter-context synchronization. This seemed fine to me since, as far as
I understdood, it is the duty of the application to synchronize itself
against multiple screens and contexts.
The problem here is that applications were actually relying on the old
behavior where the Kernel guarantees synchronization, so 89a34cb845
can be seen as a regression. This commit addresses the inter-context
synchronization case.
v2: Rebase after the changes from a90a1f15a7. This new version is
significantly different.
Cc: mesa-stable (see the backport in MR !14783)
References: https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/14783
Closes: https://gitlab.freedesktop.org/mesa/mesa/-/issues/5731
Closes: https://gitlab.freedesktop.org/mesa/mesa/-/issues/5812
Fixes: 89a34cb845 ("iris: switch to explicit busy tracking")
References: a90a1f15a7 ("iris: Create an IRIS_BATCH_BLITTER for using the BLT command streamer")
Tested-by: Konstantin Kharlamov <hi-angel@yandex.ru> (v1)
Reviewed-by: Kenneth Graunke <kenneth@whitecape.org>
Signed-off-by: Paulo Zanoni <paulo.r.zanoni@intel.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/14505>
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