[PATCH 0/3] usb: dwc3: qcom: Keep USB 2.0 working in DisplayPort-only modes

[Joonhoe Kim]

With a USB-C monitor in DisplayPort pin assignment C or E, the QMP
USB3-DP combo PHY gives all four lanes to DisplayPort and keeps its USB
PCS powered down. The USB 2.0 pair still works, and such monitors often
have a USB 2.0 hub behind them, but the dwc3 controller keeps depending on
the USB3 PIPE clock: on Kaanapali the next xHCI reset in this state
times out ("Host halt failed, -110") and USB is gone until the cable is
replugged. Commit f546912bcac6 ("phy: qcom: qmp-combo: Move pipe_clk
on/off to common") keeps the pipe clock branch enabled, which is not
enough here.

This series lets the controller be a Type-C mode switch next to the PHY
and moves it to the UTMI clock, the way "qcom,select-utmi-as-pipe-clk"
does statically, before the PHY switches to DP-only mode.

On Kaanapali the PHY becomes a mode switch with Balaji Kalkonda's
DisplayPort series [1]; patch 3 is the controller side for the same
SoC. Other SoCs whose PHY is already a mode switch (e.g. SM8650,
SM8750) may need the same property on their controller node (not
tested).

Related fixes sent separately: "phy: qcom: qmp-combo: Leave the USB PCS
alone in DP-only mode" (suspend in DP-only mode) [2] and "usb: typec:
mux: fsa4480: Keep the USB 2.0 switch on in DP-only modes" (boards with
an FSA4480 on the USB 2.0 pair) [3].

Patch 2 conflicts with Vladyslav Tymoshchuk's "usb: dwc3: qcom: Defer
VBUS override update during system suspend" [4] in struct dwc3_qcom and
dwc3_qcom_set_role_notifier(). On top of [4], the
dwc3_qcom_update_pipe_clk() call goes after its pm_suspended check, as
it also writes QSCRATCH.

Patches 1-2 are for the USB tree. Patch 3 must not be applied before
patch 2: with "mode-switch" on the controller and no mux registered by
dwc3-qcom, pmic_glink_altmode defers its probe indefinitely.

Tested on a Lenovo Y700 Gen 5 (TB323FU, Kaanapali) with a USB-C
monitor over 4-lane HBR3: the monitor's USB 2.0 hub works at boot,
after replugs and across s2idle (tested on v7.3 with these patches,
[2] and [3]).

[1] https://lore.kernel.org/all/20261022-kaanapali_dp-v3-0-b5ae8e6083c3@xxxxxxxxxxxxxxxx/
[2] https://lore.kernel.org/all/20261023123512.1912-1-26rote@xxxxxxxxx/
[3] https://lore.kernel.org/all/20261022165143.1327-1-26rote@xxxxxxxxx/
[4] https://lore.kernel.org/all/20261018143126.3978-1-tvlad744@xxxxxxxxx/

Joonhoe Kim (3):
  dt-bindings: usb: qcom,snps-dwc3: Add mode-switch
  usb: dwc3: qcom: Use the UTMI clock as PIPE clock in DisplayPort-only
    modes
  arm64: dts: qcom: kaanapali: Mark the USB controller as a Type-C mode
    switch

 .../bindings/usb/qcom,snps-dwc3.yaml          |  7 ++
 arch/arm64/boot/dts/qcom/kaanapali.dtsi       |  1 +
 drivers/usb/dwc3/dwc3-qcom.c                  | 94 +++++++++++++++++--
 3 files changed, 94 insertions(+), 8 deletions(-)


base-commit: 7649ba73f9e7e1e04d0b46213e39c79ae09dd55c
-- 
2.43.0