gallium: document convention for get_handle calls on multi-planar resources
There are resources that may have more planes than chained resources. The
frontend has no way of figuring out which (if any) chained resource is the
right one to call resource_get_handle with and until a (now reverted)
change to the dri frontend it just always called with the first resource.
The convention of calling with the first resource of a chain allows the
pipe driver, which has the necessary information of how resources and
planes map to each other for a specific format/modifier combination, to do
the necessary walking. Document this as the official calling convention
of this function.
Signed-off-by: Lucas Stach <l.stach@pengutronix.de>
Reviewed-by: Marek Olšák <marek.olsak@amd.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/7419>
1 file changed