[Bug 2138961] Re: USB-C Monitor not detected on boot (DWC3 soft reset timeout) on X1E80100/Snapdragon X Elite

** Attachment added: "Build information."
https://bugs.launchpad.net/ubuntu/+source/linux/+bug/2138961/+attachment/5940525/+files/launchpad-2138961-uname-info.tar.gz

--
You received this bug notification because you are subscribed to linux
in Ubuntu.
Matching subscriptions: Bgg, Bmail, Nb
https://bugs.launchpad.net/bugs/2138961

Title:
USB-C Monitor not detected on boot (DWC3 soft reset timeout) on
X1E80100/Snapdragon X Elite

Status in linux package in Ubuntu:
New

Bug description:
On the Lenovo Yoga Slim 7x (Snapdragon X Elite / X1E80100), if a
monitor is connected during boot, the display is often not detected or
powered up. The monitor remains black/no-signal until the cable is
physically disconnected and reconnected.

The following error appears in dmesg during the failed boot attempt:

dwc3 a000000.usb: error -ETIMEDOUT: failed to initialize core
dwc3 a000000.usb: DWC3 controller soft reset failed

Analysis: This appears to be a timing issue where the DWC3 controller
attempts to reset the core immediately after the PHY initialization,
but the PHY pipe clock has not yet stabilized. The soft reset then
times out waiting for clock synchronization.

Fix: Adding a 2ms delay in drivers/phy/qualcomm/phy-qcom-qmp-combo.c
inside qmp_combo_usb_init() (after the PHY power-on sequence) resolves
the issue reliably. This ensures the PHY clock is stable before the
DWC3 core driver takes over.

Patch: Add stabilization delay for USB pipe clock

To manage notifications about this bug go to:
https://bugs.launchpad.net/ubuntu/+source/linux/+bug/2138961/+subscriptions