display regression on Carrizo

[StDenis, Tom]

[AMD Official Use Only]

Hi Mario,

The following commit causes a display regression on my Carrizo when booting linux into a console (e.g. no WM).  When the driver inits the display goes green and is unusable.  The commit prior to this one on amd-staging-drm-next results in a clean init.

commit b1114ddd63be03825182d6162ff25fa3492cd6f5
Author: Mario Kleiner <mario.kleiner.de at gmail.com>
Date:   Fri Mar 19 22:03:15 2021 +0100

    drm/amd/display: Increase linebuffer pixel depth to 36bpp.

    Testing with the photometer shows that at least Raven Ridge DCN-1.0
    does not achieve more than 10 bpc effective output precision with a
    16 bpc unorm surface of type SURFACE_PIXEL_FORMAT_GRPH_ABGR16161616,
    unless linebuffer depth is increased from LB_PIXEL_DEPTH_30BPP to
    LB_PIXEL_DEPTH_36BPP. Otherwise precision gets truncated somewhere
    to 10 bpc effective depth.

    Strangely this increase was not needed on Polaris11 DCE-11.2 during
    testing to get 12 bpc effective precision. It also is not needed for
    fp16 framebuffers.

    Tested on DCN-1.0 and DCE-11.2.

    Signed-off-by: Mario Kleiner <mario.kleiner.de at gmail.com>
    Signed-off-by: Alex Deucher <alexander.deucher at amd.com>

 drivers/gpu/drm/amd/display/dc/core/dc_resource.c          | 7 +++++--
 drivers/gpu/drm/amd/display/dc/dce/dce_transform.c         | 6 ++++--
 drivers/gpu/drm/amd/display/dc/dce110/dce110_transform_v.c | 3 ++-
 drivers/gpu/drm/amd/display/dc/dcn10/dcn10_dpp.c           | 3 ++-
 drivers/gpu/drm/amd/display/dc/dcn10/dcn10_hw_sequencer.c  | 2 +-
 drivers/gpu/drm/amd/display/dc/dcn20/dcn20_dpp.c           | 3 ++-
 drivers/gpu/drm/amd/display/dc/dcn20/dcn20_hwseq.c         | 2 +-
 drivers/gpu/drm/amd/display/dc/dcn30/dcn30_dpp.c           | 3 ++-
 8 files changed, 19 insertions(+), 10 deletions(-)

Tom