Thanks for the pointer, but I don't think this is a duplicate of #2161309. That report is a backlight-control regression on a T480 (UHD 620 / Kaby Lake R), where the panel works but brightness is stuck — introduced in 7.0.0-28 and reportedly fixed in 7.0.0-31.
This bug is a display-resume failure on Meteor Lake (8086:7d55, DISPLAY_VER 14), in the cx0/C10 PHY path that doesn't exist on Kaby Lake hardware. The panel never comes back at all after an s2idle dwell, and the kernel logs the PHY message bus as unreachable: *ERROR* Failed to bring PHY A to idle. *ERROR* PHY A Read 0c70 failed after 3 retries. *ERROR* PHY A Write 0c70 failed after 3 retries. There's no backlight symptom here and no brightness regression — the display is entirely dead until reboot, and the state persists across further suspend/resume cycles. The closer match is #2150605 (Arrow Lake-S, same PHY A / C10 signature on resume from long s2idle dwell), plus multiple independent reports on this exact laptop model at https://bbs.archlinux.org/viewtopic.php?id=313469, where 6.19.14 is confirmed unaffected on both a P1 Gen 7 and a P1 Gen 8. I'll test i915.enable_dpcd_backlight=0 and report the result either way, but I'd ask that this not be closed as a duplicate of a Kaby Lake backlight bug. -- You received this bug notification because you are a member of Ubuntu Bugs, which is subscribed to Ubuntu. https://bugs.launchpad.net/bugs/2165164 Title: i915 Meteor Lake (ThinkPad P1 Gen 7): PHY A message bus unresponsive on resume from long s2idle dwell — C10 PLL left unprogrammed, display unrecoverable To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/linux/+bug/2165164/+subscriptions -- ubuntu-bugs mailing list [email protected] https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs
