drm/plane-helper: Skip prepare_fb/cleanup_fb when newfb==oldfb

When commiting a plane update where the framebuffer doesn't change, we
can skip the prepare_fb/cleanup_fb steps.  This also allows us to avoid
an unnecessary vblank wait at the end of the operation when we're just
moving a plane and not changing its image (e.g., for a cursor).

At the moment, i915 is the only upstream driver using the transitional
plane helpers, and thus the only driver affected by this change.

Note that this replicates a corresponding change in the atomic helpers
implemented in

commit ab58e3384b9f9863bfd029b458ff337d381bf6d2
Author: Daniel Vetter <[email protected]>
Date:   Mon Nov 24 20:42:42 2014 +0100

    drm/atomic-helper: Skip vblank waits for unchanged fbs

Reported-by: Jeremiah Mahler <[email protected]>
Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=88540
Signed-off-by: Matt Roper <[email protected]>
Tested-by: Tested-by: Rodrigo Vivi <[email protected]>
Signed-off-by: Daniel Vetter <[email protected]>

0 files changed, 0 insertions, 0 deletions