RK3399 DisplaPort no 4K resolution

Markie

Dear all,

additional info below (edit 2018-04-04)

I too try to get a DisplayPort 4K monitor  (AOC U2879VF) working, however no success yet.
I have modified the DTS-file accordingly, and I see a couple of things:

1) 'dumpsys SurfaceFlinger' shows 2 displays: "Built-in screen" and "HDMI screen". The latter is the the DisplayPort 4K monitor. The naming is hardcoded in the Android source, and reading the EDID shows it is the correct monitor (and I have no display connected via HDMI). Only one monitor via HDMI shows only "Built-in screen". I don't think this is an issue, as Android tries to clone to each video output.

2) I guess the VOP_LITTLE seems to be selected for DisplayPort output (and not the VOP_BIG), as the current mode is 2560x1440@60p and the modes list does not contain above this (also not 3840x2160p60), while the monitor is capable.

1. $cat /sys/devices/platform/display-subsystem/drm/card0/card0-DP-1/modes
   
2. 2560x1440p60
   
3. 1920x1080p60
   
4. 1920x1080p60
   
5. 1920x1080p60
   
6. ...
   

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3) Although the monitor should accept 2560x1440@60p, there is no image on the monitor and I get the following dmesg/console-output when connecting the monitor:

1. [   13.220928] fusb302 4-0022: attention, dp_status a
   
2. [   13.227559] cdn-dp fec00000.dp: [drm:cdn_dp_pd_event_work] Connected without sink. Assert hpd
   
3. [   13.287002] cdn-dp fec00000.dp: [drm:cdn_dp_pd_event_work] Connected, not enabled. Enabling cdn
   
4. [   14.239036] fusb302 4-0022: attention, dp_status 8a
   
5. [   14.241816] cdn-dp fec00000.dp: [drm:cdn_dp_pd_event_work] Connected with sink. Re-train link
   
6. [   57.438951] fusb302 4-0022: attention, dp_status 18a
   
7. [   57.444952] cdn-dp fec00000.dp: [drm:cdn_dp_pd_event_work] Connected with sink. Re-train link
   
8. [   69.396299] fusb302 4-0022: attention, dp_status 18a
   
9. [   69.402256] cdn-dp fec00000.dp: [drm:cdn_dp_pd_event_work] Connected with sink. Re-train link
   
10. [   71.460755] fusb302 4-0022: attention, dp_status 18a
    
11. [   71.467507] cdn-dp fec00000.dp: [drm:cdn_dp_pd_event_work] Connected with sink. Re-train link
    
12. [   72.984966] fusb302 4-0022: attention, dp_status 18a
    
13. [   72.992195] cdn-dp fec00000.dp: [drm:cdn_dp_pd_event_work] Connected with sink. Re-train link
    
14. [   96.583813] fusb302 4-0022: attention, dp_status a
    
15. [   96.591843] cdn-dp fec00000.dp: [drm:cdn_dp_pd_event_work] Connected with sink. Re-train link
    
16. [   97.572369] fusb302 4-0022: attention, dp_status 8a
    
17. [   97.579922] cdn-dp fec00000.dp: [drm:cdn_dp_pd_event_work] Connected with sink. Re-train link
    
18. [  138.177425] fusb302 4-0022: attention, dp_status 18a
    
19. [  138.185544] cdn-dp fec00000.dp: [drm:cdn_dp_pd_event_work] Connected with sink. Re-train link
    

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Resulting in some questions:
1) How can I verify which VOP is "used" for which display?
2) How to make sure VOP_BIG is "used"?
3) Do you have any information about this "dp_status 18a"? Maybe to suspect the monitor ...

additional info: I see a difference between boards, as I have boards with different production dates/stickers
- one board with production date 2017-08-22: see above observations
- one board with production date 2018-03-29: works out of the box! (although only 2560x1440@60p, and not yet 3840x2160@60p)
I don't know whether there is a hardware change, or it is subject to hardware component variations, ...

Thanks in advance,
With kind regards, Mark