[Working HDMI adapter@50Hz:]
jja2000@armplank:~$ sudo cat /sys/kernel/debug/dri/ae01000.display-controller/DP-1/dp_debug
[sudo] password for jja2000: 
        name = msm_dp
        drm_dp_link
                rate = 540000
                num_lanes = 2
                capabilities = 1
        dp_panel_info:
                active = 3440x1440
                back_porch = 90x39
                front_porch = 48x3
                sync_width = 32x10
                active_low = 0x0
                h_skew = 0
                refresh rate = 50
                pixel clock khz = 269310
                bpp = 30
        dp_link:
                test_requested = 128
                num_lanes = 2
                bw_code = 20
                lclk = 540000000
                v_level = 0
                p_level = 0
[Not working HDMI adapter@85Hz:]
jja2000@armplank:~$ sudo cat /sys/kernel/debug/dri/ae01000.display-controller/DP-1/dp_debug
        name = msm_dp
        drm_dp_link
                rate = 540000
                num_lanes = 2
                capabilities = 1
        dp_panel_info:
                active = 3440x1440
                back_porch = 144x61
                front_porch = 48x3
                sync_width = 32x10
                active_low = 0x0
                h_skew = 0
                refresh rate = 85
                pixel clock khz = 471520
                bpp = 30
        dp_link:
                test_requested = 128
                num_lanes = 2
                bw_code = 20
                lclk = 540000000
                v_level = 0
                p_level = 0