I was not able to test it on my own, this is a call for testing for the owners of these platforms. The git version of modetest now fully supports writeback.
Use libdrm >= 2.4.117, run modetest -ac to determine the writeback connector, cat /sys/kernel/debug/dri/0/state to determine spare CRTC and plane, then run something like: modetest -M msm -a -s 36@85:1024x768 -o test.d -P 79@85:1024x768 where 36 is the Writeback connector id, 85 is CRTC and 79 is the plane. Then press Enter and check the test.d file for the raw image dump. Changes since v1: - Fixed the DPU_CLK_CTRL_WB2 definition Dmitry Baryshkov (4): drm/msm/dpu: enable writeback on SM8150 drm/msm/dpu: enable writeback on SC8108X drm/msm/dpu: enable writeback on SM6125 drm/msm/dpu: enable writeback on SM6350 .../drm/msm/disp/dpu1/catalog/dpu_5_0_sm8150.h | 18 ++++++++++++++++++ .../msm/disp/dpu1/catalog/dpu_5_1_sc8180x.h | 18 ++++++++++++++++++ .../drm/msm/disp/dpu1/catalog/dpu_5_4_sm6125.h | 18 ++++++++++++++++++ .../drm/msm/disp/dpu1/catalog/dpu_6_4_sm6350.h | 18 ++++++++++++++++++ 4 files changed, 72 insertions(+) -- 2.39.2
