sc7180 lazor: Image corruption regression for DP with v6.8-rc4

Hi @abhinavk @lumag,

in case you are not yet aware of this issue, I noticed a regression on v6.8-rc4 compared to v6.7 kernel causing image corruption when connecting an external display to my sc7180 trogdor lazor device. The output on the external display does not become completely unrecognizable, but get's obscured by a large number of colorful boxes. The issue is accompanied by the following drm messages in dmesg when connecting the external display:

[  140.142945] [drm:_dpu_rm_check_lm_and_get_connected_blks] [dpu error]failed to get dspp on lm 0                                                    
[  140.151987] [drm:_dpu_rm_make_reservation] [dpu error]unable to find appropriate mixers                                                            
[  140.160246] [drm:dpu_rm_reserve] [dpu error]failed to reserve hw resources: -119                                                                   

The laptop panel / display continues to work the same before, during and after connecting an external display via the USB-C DP and causing the issue.

Please let me know if any additional information from my side would help.

Thank you Leonard