On Gen6, the blending necessary to blit an MSAA surface to a non-MSAA
surface could be accomplished with a single texturing operation. On
Gen7, the WM program must fetch each sample and blend them together
manually. From the Bspec (Shared Functions/Messages/Initiating
Message/Message Types/sample):
[DevIVB+]:Number of Multisamples on the associated surface must be
MULTISAMPLECOUNT_1.
This patch implements the manual blend operation.
Acked-by: Kenneth Graunke <kenneth@whitecape.org>
Paul Berry
4725ba03ca