Public bug reported:
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
** Affects: linux (Ubuntu)
Importance: Undecided
Status: New
** Tags: arm64 x1e
** Patch added: "[PATCH] phy: qcom-qmp-combo: Add stabilization delay for USB
pipe clock"
https://bugs.launchpad.net/bugs/2138961/+attachment/5940461/+files/0001-phy-qcom-qmp-combo-Add-stabilization-delay-for-USB-p.patch
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https://bugs.launchpad.net/bugs/2138961
Title:
USB-C Monitor not detected on boot (DWC3 soft reset timeout) on
X1E80100/Snapdragon X Elite
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