Display resolution of monitor via HDMI incorrectly identified

[thet]

I use a Philips BDM4037U 40'', 4k monitor.
Connecting it via DP to my Lenovo 910 4k does work (except for random display blackouts).

But when connecting it via HDMI the display resolution is sometimes correctly set (I cannot see a pattern when this works) but sometimes the display resolution is just set to FullHD, 1920x1080 Pixel @ 60Hz.

Due to limitations of the supported HDMI protocol on my laptop I can only drive the display with 30Hz when in 4k mode. Which is totally fine for me. But this mode isn't correctly identified, most of the time.

ProblemType: Bug
DistroRelease: Ubuntu 18.04
Package: linux-image-4.15.0-13-generic 4.15.0-13.14 [modified: boot/vmlinuz-4.15.0-13-generic]
ProcVersionSignature: Ubuntu 4.15.0-13.14-generic 4.15.10
Uname: Linux 4.15.0-13-generic x86_64
ApportVersion: 2.20.9-0ubuntu4
Architecture: amd64
AudioDevicesInUse:
 USER PID ACCESS COMMAND
 /dev/snd/controlC0: thet 1429 F.... pulseaudio
CurrentDesktop: ubuntu:GNOME
Date: Wed Apr 11 12:00:28 2018
HibernationDevice: RESUME=UUID=bedd1248-32dd-43ca-be9f-28337086ea86
InstallationDate: Installed on 2018-04-09 (1 days ago)
InstallationMedia: Ubuntu 18.04 LTS "Bionic Beaver" - Beta amd64 (20180404)
MachineType: LENOVO 80VF
ProcFB: 0 inteldrmfb
ProcKernelCmdLine: BOOT_IMAGE=/vmlinuz-4.15.0-13-generic.efi.signed root=UUID=998520ff-c841-45ab-8312-2bb876ae2a0b ro quiet splash vt.handoff=1
RelatedPackageVersions:
 linux-restricted-modules-4.15.0-13-generic N/A
 linux-backports-modules-4.15.0-13-generic N/A
 linux-firmware 1.173
SourcePackage: linux
UpgradeStatus: No upgrade log present (probably fresh install)
dmi.bios.date: 05/31/2017
dmi.bios.vendor: LENOVO
dmi.bios.version: 2JCN39WW
dmi.board.asset.tag: NO Asset Tag
dmi.board.name: Agera
dmi.board.vendor: LENOVO
dmi.board.version: SDK0J40709 WIN
dmi.chassis.asset.tag: NO Asset Tag
dmi.chassis.type: 31
dmi.chassis.vendor: LENOVO
dmi.chassis.version: Lenovo YOGA 910-13IKB
dmi.modalias: dmi:bvnLENOVO:bvr2JCN39WW:bd05/31/2017:svnLENOVO:pn80VF:pvrLenovoYOGA910-13IKB:rvnLENOVO:rnAgera:rvrSDK0J40709WIN:cvnLENOVO:ct31:cvrLenovoYOGA910-13IKB:
dmi.product.family: IDEAPAD
dmi.product.name: 80VF
dmi.product.version: Lenovo YOGA 910-13IKB
dmi.sys.vendor: LENOVO

[thet (thet)]

Some additional notes:
- The same problem existed in 17.10 as well as in 18.04 beta, with x-org and Wayland sessions.
- There is another bug regarding DP issues by me - but should be unrelated to the HDMI problem: https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1762989

[Ubuntu Kernel Bot (ubuntu-kernel-bot)]

This change was made by a bot.

[Joseph Salisbury (jsalisbury)]

Did this issue start happening after an update/upgrade? Was there a prior kernel version where you were not having this particular problem?

Would it be possible for you to test the latest upstream kernel? Refer to https://wiki.ubuntu.com/KernelMainlineBuilds . Please test the latest v4.16 kernel[0].

If this bug is fixed in the mainline kernel, please add the following tag 'kernel-fixed-upstream'.

If the mainline kernel does not fix this bug, please add the tag: 'kernel-bug-exists-upstream'.

Once testing of the upstream kernel is complete, please mark this bug as "Confirmed".

Thanks in advance.

[0] http://kernel.ubuntu.com/~kernel-ppa/mainline/v4.16

[thet (thet)]

The issue did start appearing after an update on 17.10. I bought the Monitor on 29.11.2017, so it worked with the 17.10 kernel version around that time. Since HDMI on 4k only drives the Monitor @30Hz on my laptop, I bought a DP adapter. After the random screen black outs annoyed me too much I switched back to HDMI (around early this year). The monitor wasn't reliably recognized as a 4k monitor anymore.

- I installed the 4.16 Kernel from http://kernel.ubuntu.com/~kernel-ppa/mainline/v4.16.1/
- Powered the laptop off
- Switched from DP to HDMI adapter
- Boot up with 4.16.1 kernel

Monitor resolution was correctly identified

- Rebooted with 4.16.1 kernel

Monitor was not anymore correctly identified. Instead of 3840x2160@30hz the was at 1920x1080@60Hz

Maybe relvant HDMI adapter info:
My Lenovo Yoga 910 has a combined Type-C USB3 & DP 1.2 connector.
The adapter is a LMP HDMI & USB adapter:
https://www.lmp-adapter.com/en/products/cables--adapters/usb-c/lmp-usb-c-to-hdmi-multiport-adapter

[thet (thet)]

I just tried another USB-C to HDMI adapter from a friend without any issues.
I believe now that this isn't a problem with the kernel but the adapter.
The issue can probably be closed.

[thet (thet)]

New theory: The monitor must be on, booted up and still not in sleep mode when the HDMI USB-C adapter is attached to the laptop. I could get the correct resolution already twice with this procedure.