[enhancement] android hwc overlay could optimize movement of surfaces without buffer update

[Kevin DuBois]

Currently, we check in the hwc code that a buffer has changed from the previous commit to avoid submitting the same thing to the screen twice. This does not factor in changes to the the screen positioning. If it did, we could optimize a few more scenarios using 2d acceleration.

This won't cause rendering glitches, just a bit worse performance in some non-critical-path scenarios.

[Kevin DuBois (kdub)]

raised priority to medium because it affects the touchspot rendering

[Kevin DuBois (kdub)]

This turned out to be a bit trickier to implement than first anticipated, due to the fact that we can run out of internal resources in certain of certain drivers (n10) if the same buffer is submitted repeatedly. We have to shift how we wait for fences a bit, but it seems like too much of a refactoring to undertake for these performance scenarios right before rtm.

[Kevin DuBois (kdub)]

untargetting, not in progress

[Daniel van Vugt (vanvugt)]

The Android platform was deleted from lp:mir at revision 4155.