SRU Justification:
Impact:
On some setups, while the monitor and the gpu support display modes with pixel clocks of up to 600MHz, the link encoder might not. This prevents YCbCr444 and RGB encoding for 4k60Hz, but YCbCr420 encoding might still be possible. However, which color mode is used is decided before the link encoder capabilities are checked, causing the check to fail and discarding 4k60Hz from the list of possible display modes.
Fix:
This patch fixes the problem by retrying to find a display mode with YCbCr420 enforced and using it, if it is valid.
Testcase:
Tested on an Clevo NL50RU. General: Find a PC with a current AMD Radeon GPU, but only a hdmi 1.4 output (e.g. current Clevo laptops with AMD APU's). Connect a 4k@60Hz display supporting YCbCr420 encoding to the hdmi port. Without the patch the maximum that can be set via xrandr is 3840 × 2160 30Hz. With the Patch 3840 × 2160 60Hz can be selected which will use YCbCr420 automatically.
Patch already got accepted upstream for linux-next: https://git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git/commit/?id=14e4a095b29fd290a9b80f6e553adcfcf01672d1 and applies without modifications to ubuntu-focal/hwe-5.8
Commit-hash: 14e4a095b29fd290a9b80f6e553adcfcf01672d1
---
ProblemType: Bug
ApportVersion: 2.20.11-0ubuntu27.16
Architecture: amd64
AudioDevicesInUse:
USER PID ACCESS COMMAND
/dev/snd/controlC1: test 2903 F.... pulseaudio
/dev/snd/controlC0: test 2903 F.... pulseaudio
CasperMD5CheckResult: skip
CurrentDesktop: Budgie:GNOME
DistroRelease: Ubuntu 20.04
MachineType: TUXEDO TUXEDO Aura 15 Gen1
Package: linux (not installed)
ProcFB: 0 amdgpudrmfb
ProcKernelCmdLine: BOOT_IMAGE=/boot/vmlinuz-5.8.0-48-generic root=UUID=59a028a1-0764-418a-951d-515f1839bd7f ro ignore_loglevel quiet splash i8042.reset i8042.nomux i8042.nopnp i8042.noloop xhci_hcd.quirks=1073741824 vt.handoff=7
ProcVersionSignature: Ubuntu 5.8.0-48.54~20.04.1-generic 5.8.18
RelatedPackageVersions:
linux-restricted-modules-5.8.0-48-generic N/A
linux-backports-modules-5.8.0-48-generic N/A
linux-firmware 1.187.9
Tags: focal
Uname: Linux 5.8.0-48-generic x86_64
UpgradeStatus: No upgrade log present (probably fresh install)
UserGroups: adm cdrom dip lpadmin plugdev sambashare sudo
_MarkForUpload: True
dmi.bios.date: 11/13/2020
dmi.bios.release: 7.3
dmi.bios.vendor: INSYDE Corp.
dmi.bios.version: 1.07.03RTR2
dmi.board.asset.tag: Tag 12345
dmi.board.name: AURA1501
dmi.board.vendor: TUXEDO Computers
dmi.board.version: Not Applicable
dmi.chassis.asset.tag: No Asset Tag
dmi.chassis.type: 10
dmi.chassis.vendor: Notebook
dmi.chassis.version: N/A
dmi.modalias: dmi:bvnINSYDECorp.:bvr1.07.03RTR2:bd11/13/2020:br7.3:svnTUXEDO:pnTUXEDOAura15Gen1:pvrNotApplicable:rvnTUXEDOComputers:rnAURA1501:rvrNotApplicable:cvnNotebook:ct10:cvrN/A:
dmi.product.family: Not Applicable
dmi.product.name: TUXEDO Aura 15 Gen1
dmi.product.sku: AURA1501
dmi.product.version: Not Applicable
dmi.sys.vendor: TUXEDO
This bug is missing log files that will aid in diagnosing the problem. While running an Ubuntu kernel (not a mainline or third-party kernel) please enter the following command in a terminal window:
apport-collect 1922754
and then change the status of the bug to 'Confirmed'.
If, due to the nature of the issue you have encountered, you are unable to run this command, please add a comment stating that fact and change the bug status to 'Confirmed'.
This change has been made by an automated script, maintained by the Ubuntu Kernel Team.