[PATCH v2 0/4] drm/vc4: Improve alpha format plane support

[Stefan Schake]

This series improves the handling of alpha formats with the VC4 HVS
compositor. Alpha formats are marked as premultiplied as is standard
for DRM. Further fix a display corruption issue when planes with
per-pixel alpha try blending from the (nonexistent) background by
selectively enabling a black background color fill.

This series follows the changes suggested by Eric Anholt in a previous
patch discussion:

https://patchwork.freedesktop.org/patch/207667/

A simple test program for the display corruption issue is available:

https://github.com/stschake/vc4-alpha-test

v2 of the series fixes the has_alpha confusion and moves needs_bg_fill
into the plane state. This unfortunately necessitated moving the plane
state to a header where it can be referenced from vc4_crtc.

Stefan Schake (4):
  drm/vc4: Set premultiplied for alpha formats
  drm/vc4: Check if plane requires background fill
  drm/vc4: Move plane state to header
  drm/vc4: Enable background color fill when necessary

 drivers/gpu/drm/vc4/vc4_crtc.c  | 25 +++++++++++++++
 drivers/gpu/drm/vc4/vc4_drv.h   | 60 ++++++++++++++++++++++++++++++++++++
 drivers/gpu/drm/vc4/vc4_plane.c | 68 ++++++++---------------------------------
 drivers/gpu/drm/vc4/vc4_regs.h  |  1 +
 4 files changed, 99 insertions(+), 55 deletions(-)

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2.7.4