https://bugs.freedesktop.org/show_bug.cgi?id=110780

Bug ID: 110780 Summary: RX 580 and 5K displays, bandwidth validation failed with multiple monitors Product: DRI Version: unspecified Hardware: All OS: Linux (All) Status: NEW Severity: major Priority: medium Component: DRM/AMDgpu Assignee: dri-devel@lists.freedesktop.org Reporter: linuzel@gmail.com

I have been facing an issue with my 5K display (iiyama ProLite XB2779QQS-S1).

It works fine as long as it is the only active monitor, as soon as I activate another monitor the main one (5k) can't display more than 4k.

Debug using "echo 0x4 > /sys/module/drm/parameters/debug" show this : mai 23 09:01:22 bureau-gael /usr/lib/gdm3/gdm-x-session[3465]: (EE) AMDGPU(0): failed to set mode: Invalid argument mai 23 09:01:22 bureau-gael kernel: [drm:dce112_validate_bandwidth [amdgpu]] dce112_validate_bandwidth: Bandwidth validation failed!

I disabled the check by forcing is_display_configuration_supported to return true in dce_calcs.c and it works fine.

I tried a lot of kernel (includig drm-tip and 5.2-rc1) and they all have the same issue. My custom kernel with no validation is based on Ubuntu's 5.0.0-15-generic.

If I can help by providing more logs or test something ask and I will do my best.