Thanks for your work I just bought and tried a new 4K hdmi cable, with no change. I noticed that the monitor has TWO inputs, HDMI and HDMI/MHL (it had been plugged into HDMI) but switching this to HDMI/MHL gave no result.
I am using MATE but the same issue occurs in several flavours of Ubuntu that I have tried. I dont know how to try the new kernel at https://kernel.ubuntu.com/~kernel-ppa/mainline/v5.8/ as you requested. If I attempt to ask Gdebi to load the linux-image-unsigned-5.8.0-050800-generic_5.8.0-050800.202008022230_amd64.deb package from https://kernel.ubuntu.com/~kernel-ppa/mainline/v5.8/amd64/ it fails with unmet dependencies. kernel-modes.txt is attached ** Attachment added: "kernel-modes.txt" https://bugs.launchpad.net/ubuntu/+source/xorg-server/+bug/1890418/+attachment/5399129/+files/kernel-modes.txt -- You received this bug notification because you are a member of Kernel Packages, which is subscribed to linux in Ubuntu. https://bugs.launchpad.net/bugs/1890418 Title: i915 does not expose vendor-specific extended HDMI timings/modes Status in linux package in Ubuntu: Incomplete Status in xorg-server package in Ubuntu: Incomplete Bug description: I have a Toshiba radius 11 laptop which has a 4 k native screen. I have connected an Asus PB287Q 28" external monitor (https://www.asus.com/us/Commercial-Monitors/PB287Q/specifications/) over HDMI which displays the full 4K resolution when running under windows10 but will only reach a maximum resolution of 1920x1080 under ubuntu 20.04, same hardware just dual booting. Under Monitor Preferences this monitor is detected as an "Ancor Communications inc 28" and the monitor preferences provides a number of resolution steps up to 1920. If I issue "xrandr --addmode HDMI-1 3840x2160" this resolution is added to the monitor preferences pick list but attempting to apply it results in "the selected configuration for displays could not ..." message To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1890418/+subscriptions -- Mailing list: https://launchpad.net/~kernel-packages Post to : kernel-packages@lists.launchpad.net Unsubscribe : https://launchpad.net/~kernel-packages More help : https://help.launchpad.net/ListHelp