[v4] usb: typec: ps883x: fixes for older Thunderbolt 4 / USB4 docks

[PATCH v4 0/3] usb: typec: ps883x: fixes for older Thunderbolt 4 / USB4 docks
Posted by Jens Glathe via B4 Relay 2 days, 2 hours ago
On Qualcomm X1E80100 / X1P42100 platforms using the Parade PS883x
retimer, connecting USB4-capable docks such as the Lenovo 40B0 via a
regular Type-C cable (Type-C fallback mode) often results in working
USB but no DisplayPort output.

This series addresses the issue with three driver-only changes:

- Support the legacy TYPEC_DP_STATE_F request (deprecated since DP Alt
  Mode 1.0b) that docks such as the 40B0 and SSK SC220 still send.
  Handle it in the existing DP altmode path in ps883x_set(). F is 
  programmed like D; E is unchanged.

- Add a post-configuration delay after writing the connection-status
  registers so the analog front-end can settle. This makes DP Alt Mode
  hotplug reliable on the 40B0.

- On platforms whose USB4 / DP-tunneling stack is not ready yet, reject
  TYPEC_MODE_USB4 with -EOPNOTSUPP. That forces the Type-C stack to
  fall back to USB3 + DP Alt Mode. The quirk is a machine-compatible
  table inside the driver, not a DT property.

This is a temporary workaround until full USB4 DP tunneling support is
available in the X1E USB4 controller and qmp-combo PHY stack.

As an additional observation, the same dock with a Type-C cable works
well on Thinkpad X13s, Thinkbook 16 G7 QOY and Ideapad 5 14Q8X9, which
do not use this retimer.

To: Heikki Krogerus <heikki.krogerus@linux.intel.com>
To: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To: Abel Vesa <abelvesa@kernel.org>
To: Bjorn Andersson <andersson@kernel.org>
To: Konrad Dybcio <konradybcio@kernel.org>
To: Sebastian Reichel <sre@kernel.org>
Cc: linux-usb@vger.kernel.org
Cc: linux-kernel@vger.kernel.org
Cc: linux-arm-msm@vger.kernel.org
Cc: stable@vger.kernel.org
Cc: Dr. David Alan Gilbert <dave@treblig.org>
Cc: Dmitry Baryshkov <dmitry.baryshkov@oss.qualcomm.com>

Assisted-by: Grok(xAI):4.6
Signed-off-by: Jens Glathe <jens.glathe@oldschoolsolutions.biz>
---
Changes in v4:
- remove ambiguous link in patch 3, pointing to a semi-related issue.
- Link to v3: https://lore.kernel.org/r/20260916-ps883x-disable-usb4-v3-0-8f19386456d0@oldschoolsolutions.biz

Changes in v3:
- reduced the dp logic changein ps883x_set() to only adding 
  TYPEC_DP_STATE_F handling grouped with TYPEC_DP_STATE_D.
- picked up Tested-by tag from David, thanks for the re-test.
- Link to v2: https://lore.kernel.org/r/20260914-ps883x-disable-usb4-v2-0-523c32b4e4d7@oldschoolsolutions.biz

Changes in v2:
- Drop the parade,disable-usb4 DT property, bindings and board DTS
  changes (Sebastian Reichel, Krzysztof Kozlowski). DT describes
  hardware; incomplete software support is not a board property.
- Disable USB4 from the driver via of_machine_is_compatible() for
  qcom,x1e80100, qcom,x1p42100, qcom,hamoa and qcom,purwa. The quirk
  stays kernel-contained and can be dropped later without ABI.
- Keep DP altmode handling in the existing ps883x_set() path instead
  of extracting a helper (Konrad Dybcio). Treat STATE_F like STATE_D
  and STATE_E like STATE_C, matching qcom-qmp-combo.
- Replace usleep_range(20000, 30000) with fsleep(30000) and document
  why the delay is required (Heikki Krogerus).
- Drop the per-event "USB4 disabled via DT property" log; print once
  at probe when the quirk is active.
- Link to v1: https://lore.kernel.org/r/20260718-ps883x-disable-usb4-v1-0-cec86d0b909e@oldschoolsolutions.biz

---
Jens Glathe (3):
      usb: typec: mux: ps883x: support TYPEC_DP_STATE_F
      usb: typec: mux: ps883x: add a delay after writing config regs
      usb: typec: mux: ps883x: disable USB4 on incomplete USB4 platforms

 drivers/usb/typec/mux/ps883x.c | 48 ++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 48 insertions(+)
---
base-commit: 601057b3eec13d1f37e5b45dd1410facd7b1bdeb
change-id: 20260718-ps883x-disable-usb4-19b0fc13b5ab

Best regards,
-- 
Jens Glathe <jens.glathe@oldschoolsolutions.biz>