mesa-kms GL-renders a blank black frame on startup

[Daniel van Vugt]

mesa-kms GL-renders a blank black frame on startup. You notice this particularly with mir_proving_server on slow systems or in valgrind as the mouse cursor appears over a plain black background before the screen gets cleared to grey...

mgm::DisplayBuffer::DisplayBuffer()
    ...
    glClear(GL_COLOR_BUFFER_BIT);

    if (!egl.swap_buffers())
        fatal_error("Failed to perform initial surface buffer swap");

Ideally nothing should get rendered until the renderer/compositor starts.

[Michał Sawicz (saviq)]

Syncing task from Mir.