Problem with 2k hdmi output(half screen blank) - Raspberry Pi Forums

i have lcd printer controled pi,and host server photonic3d(https://github.com/area515/photonic3d), lcd 5.5inch (2560*1440 resolution) connected pi through hdmi port.after many times' tests, got image showed on lcd screen.
it's looks not right,please @ pic below

above half screen doesn't show anything, , below...has been divided 2 parts
here' config.txt

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hdmi_force_hotplug=1  disable_overscan=1  framebuffer_depth=24  gpu_mem=192  framebuffer_ignore_alpha=1     hdmi_ignore_edid=0xa5000080  #hdmi_cvt 2560 1440 50 3 0 0 1  hdmi_cvt 2560 1440 50  hdmi_group=2  hdmi_mode=87  hdmi_pixel_freq_limit=500000000  hvs_priority=0x32ff  config_hdmi_boost=4  framebuffer_width=2560  framebuffer_height=1440 

, tvservice -s :

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tvservice -s  state 0x120006 [dvi dmt (87) rgb full 16:9], 2560x1440 @ 50.00hz, progressive 

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tvservice -m dmt  group dmt has 20 modes:             mode 4: 640x480 @ 60hz 4:3, clock:25mhz progressive              mode 5: 640x480 @ 72hz 4:3, clock:31mhz progressive              mode 6: 640x480 @ 75hz 4:3, clock:31mhz progressive              mode 8: 800x600 @ 56hz 4:3, clock:36mhz progressive              mode 9: 800x600 @ 60hz 4:3, clock:40mhz progressive              mode 10: 800x600 @ 72hz 4:3, clock:50mhz progressive              mode 11: 800x600 @ 75hz 4:3, clock:49mhz progressive              mode 16: 1024x768 @ 60hz 4:3, clock:65mhz progressive              mode 17: 1024x768 @ 70hz 4:3, clock:75mhz progressive              mode 18: 1024x768 @ 75hz 4:3, clock:78mhz progressive              mode 21: 1152x864 @ 75hz 4:3, clock:108mhz progressive              mode 28: 1280x800 @ 60hz 16:10, clock:83mhz progressive              mode 32: 1280x960 @ 60hz 4:3, clock:108mhz progressive              mode 35: 1280x1024 @ 60hz 5:4, clock:108mhz progressive              mode 36: 1280x1024 @ 75hz 5:4, clock:135mhz progressive              mode 47: 1440x900 @ 60hz 16:10, clock:106mhz progressive              mode 48: 1440x900 @ 75hz 16:10, clock:136mhz progressive              mode 51: 1600x1200 @ 60hz 4:3, clock:162mhz progressive              mode 58: 1680x1050 @ 60hz 16:10, clock:146mhz progressive      (prefer) mode 87: 2560x1440 @ 50hz 16:9, clock:256mhz progressive   

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fbset -s     mode "1920x1200"      geometry 1920 1200 1920 1200 24      timings 0 0 0 0 0 0 0      rgba 8/16,8/8,8/0,0/24   endmode 

btw:i don't know why fbset -s 's result different real resolution
guess maybe rotate problem, fail 2k@50hz(usb wifi crash,and can't operate ssh), when change 2k@24hz, rotation success(just looks success, shows same image), can't find anyway fix now, can solve this? thanks!

hi,
1.) tft use? paneloook doens't list 5.5in display 2560x1440pixels.
2.) think have use custom hdmi timing instead of hdmi_cvt --> refer viewtopic.php?f=29&t=24679
joerg

raspberrypi