[mako] Mir servers flash up an old stale frame on startup

[Daniel van Vugt]

Mir servers flash up an old stale frame on start-up. Verified on mako at least.

Test case:
   1. sudo stop lightdm
   2. mirbacklight 100
   3. mir_demo_server_minimal

Expected: Black screen and cursor to become visible.
Observed: Screen flashes with an old frame before the black screen of the Mir demo server.

[Alberto Aguirre (albaguirre)]

A minimal test case where hwc is asked to just turn the display on (
http://pastebin.ubuntu.com/11914833/) seems to indicate this is a driver issue. I see a flash of old content before the display is blanked out.

Perhaps we could workaround it by compositing empty frames (or giving hwc empty lists? ) when turning off the display.

[Daniel van Vugt (vanvugt)]

Sounds like something we just need to be aware of and work with it... Make sure our backlight-on commands never come before the correct frame has been composited.

[Daniel van Vugt (vanvugt)]

Actually it's pretty obvious. Nothing else could reasonably be expected to work. The screen can't display the right thing if the right thing hasn't been flipped to the screen yet.

[Daniel van Vugt (vanvugt)]

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