On 22/08/2025 18:14, Melissa Wen wrote:
Hey, KDE/Plasma users reported some flickering when applying the regamma CRTC LUT to an AMD display hardware set using an external or integrated screen. There is some instability in how the driver stores and updates color blocks based on color management changes or full update request. It uses update_flag bits for surface and stream and forces some color blocks to update without considering the previous settings. This two-patch series avoids this issue by (1) not calling set_output_transfer_func when the output TF has not changed; (2) preserve the previous out_tf value in the case of a full update, which was unconditionally setting all update_flag bits to true regardless of previous values. This modifies DC and may affect behavior on other platforms. On the other hand, it avoids unnecessary reprogramming of MPC output gamma.
I linked in each patch but better refer the AMD issue here too: - https://gitlab.freedesktop.org/drm/amd/-/issues/4444
Melissa Melissa Wen (2): Revert "drm/amd/display: program output tf when required" drm/amd/display: don't update out gamma if out_tf didn't change drivers/gpu/drm/amd/display/dc/core/dc.c | 5 +++++ drivers/gpu/drm/amd/display/dc/hwss/dcn20/dcn20_hwseq.c | 5 +---- 2 files changed, 6 insertions(+), 4 deletions(-)
