Created attachment 133284 [details] ddcutil on intel I have a desktop with a Samsung SA850HD and an Acer XB270HU, both connected with DP. The Acer screen does not return any EDID and reports I2C nack when plugged in, both on the intel iGPU as well as on a HD7850 card. The Samsung screen works great. It also doesn't matter if I plug in just the Acer, it happens in single and multimonitor mode (for amdgpu/radeon). What's more, the Acer screen works perfectly fine when plugged into a GTX980 with Nouveau driver (on another box booted with Ubuntu 17.04 live cd). So the screen itself is fine. It also reports all valid data with softMCCS in Windows; full DDC control is available there. This is on 4.12.5 x86_64, Debian sid. Relevant smoking gun on intel: [ 74.733494] [drm:intel_dp_start_link_train] Clock recovery check failed, cannot continue channel equalization [ 74.737037] [drm:drm_dp_i2c_do_msg] I2C nack (result=0, size=0 I've attached logs generated with ddcutil for each card which will show summarized system info; I will attach full drm.debug=0xe dmesg shortly, please advise if more info is needed.
Created attachment 133285 [details] ddcutil interrogate on amdgpu
Created attachment 133286 [details] ddcutil interrogate on gtx980 (ubuntu 17.04 live)
Created attachment 133297 [details] full debug dmesg with amdgpu
Created attachment 133301 [details] full debug dmesg with intel igpu
Adding tag into "Whiteboard" field - ReadyForDev *Status is correct *Platform is included *Feature is included *Priority and Severity correctly set *Logs included
First of all. Sorry about spam. This is mass update for our bugs. Sorry if you feel this annoying but with this trying to understand if bug still valid or not. If bug investigation still in progress, please ignore this and I apologize! If you think this is not anymore valid, please comment to the bug that can be closed. If you haven't tested with our latest pre-upstream tree(drm-tip), can you do that also to see if issue is valid there still and if you cannot see issue there, please comment to the bug.
Closing, please re-open is issue still exists.
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