Code review comment for lp:~glmark2-dev/glmark2/canvas-drm-rebranch

Rendering works fine on the platforms I have tested. The only problems I see are during shutdown:

1. Pressing Ctrl+C occasionally doesn't seem to reset the crtc correctly, so I end up with a blank screen. It also always causes an error message to be displayed (Error in select: -1).

2. Pressing Enter (and therefore flushing stdin), causes a segfault. This happens because we are leaving DRMState::do_flip() with both surface buffers locked. Next time we call gbm_surface_lock_front_buffer(surface_) we get back a NULL value which we currently don't handle properly (i.e. we just use it). We get into the same situation if select fails etc

(1) is not critical, so I am ok with shipping this as part of an experimental drm backend release (perhaps we could add a warning about the experimental status when startinp up?).

On the other hand, I think (2) should be fixed before this release, if possible, as it's relatively easy for a user to cause a segfault. For example, a user that wants to quit will probably try pressing ESC (which won't work), then some keys then Enter.