From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mx.treblig.org (mx.treblig.org [46.235.229.95]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id D7CA146C4C1; Tue, 21 Jul 2026 16:24:15 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=46.235.229.95 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1784651058; cv=none; b=ekKhJZAjc/U16ZwkVWijasDUIMyLrCRUGvkUkH7XsuW/pDH5J8+M3HnmlMP8O0VBeHiDGZ6WSs9XTsfRtfXKkDWA866mPLdO1xrjr1AZhGtpDx7x0jT6X1U9IwBMdRRELeyfgpBgVYMNV4Q069pA6TxWndfMsaAe+VIQEvc37Ds= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1784651058; c=relaxed/simple; bh=M9GKnOVRc/2iHlLIA3YgV+hx5vodnl63NAEXok14bYw=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=c9ySaVr1uhS52wm+r1BmIpLMde6eVYaHFlIxO6+EkKZx+ShNO2hWD3tUQ5iobR31qg4CuKrxFFbSTH3RSwRmx+tx5cKSJe/ZUrpmHyfg0duIhgt4itBOqqmc20DW0zu7iY1ilNrSDuNkWJHV5AAuJpbqTk0wTgi3c/R5zUEDhvg= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=treblig.org; spf=pass smtp.mailfrom=treblig.org; dkim=pass (2048-bit key) header.d=treblig.org header.i=@treblig.org header.b=sKeqSJ4c; arc=none smtp.client-ip=46.235.229.95 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=treblig.org Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=treblig.org Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=treblig.org header.i=@treblig.org header.b="sKeqSJ4c" DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=treblig.org ; s=bytemarkmx; h=Content-Type:MIME-Version:Message-ID:Subject:From:Date:From :Subject; bh=60gNMuhoz8j9+PHZRsoGHJO6R5ote4Ye5QsNIwP9wFs=; b=sKeqSJ4cokJv3F06 0TBnsQ9f8oW6sILXv8FY9kw4IoQUkSy1CakfshXlAOWVHOBcOxUpxdDtymmRYQwvZYFP8UD4sHjbE 1qe7QhfPcoI86qa0aBCtUGPKgqEt4xLvu4zN2OXPmJjYURP9rbn1/KUohkl/CtHLFTXfJWtOFS1W8 4nyXeSg9PArGvoKpmwodBEvZtmGSV4VJB/wvD8MHisNx8ZzZ6Wumi5osCXmo/krAaHmwilGn1zIbq qR5dfq/1isdgQYzXnO9G0qxXd6/LW8J3cbRCT/DwDmgP3PD+vZF1TFrFqyxQkE0vZtObF6/UcqHC/ pB4fuKlTgMUv5Sr84g==; Received: from dg by mx.treblig.org with local (Exim 4.98.2) (envelope-from ) id 1wmDGI-00000004GGV-2hBv; Tue, 21 Jul 2026 16:24:06 +0000 Date: Tue, 21 Jul 2026 16:24:06 +0000 From: "Dr. David Alan Gilbert" To: Sebastian Reichel Cc: jens.glathe@oldschoolsolutions.biz, Greg Kroah-Hartman , Rob Herring , Krzysztof Kozlowski , Conor Dooley , Abel Vesa , Heikki Krogerus , Bjorn Andersson , Konrad Dybcio , linux-usb@vger.kernel.org, devicetree@vger.kernel.org, linux-kernel@vger.kernel.org, linux-arm-msm@vger.kernel.org, stable@vger.kernel.org Subject: Re: [PATCH 0/5] usb: typec: ps883x: fixes for older Thunderbolt 4 / USB4 docks Message-ID: References: <20260718-ps883x-disable-usb4-v1-0-cec86d0b909e@oldschoolsolutions.biz> Precedence: bulk X-Mailing-List: devicetree@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Disposition: inline In-Reply-To: X-Chocolate: 70 percent or better cocoa solids preferably X-Operating-System: Linux/6.12.95+deb13-amd64 (x86_64) X-Uptime: 16:22:39 up 15 days, 16:03, 2 users, load average: 0.05, 0.03, 0.00 User-Agent: Mutt/2.2.13 (2024-03-09) * Sebastian Reichel (sre@kernel.org) wrote: > Hello, > > On Sat, Jul 18, 2026 at 07:06:28PM +0200, Jens Glathe via B4 Relay wrote: > > On Qualcomm X1E80100 platforms (e.g. Lenovo ThinkPad T14s Gen 6) > > using the Parade PS883x retimer, connecting USB4-capable docks such > > as the Lenovo 40B0 via a regular Type-C cable (which forces the dock > > into Type-C fallback mode) often results in working USB but no > > DisplayPort output. > > > > This series addresses the issue with two main changes: > > > > - Add a new optional DT property "parade,disable-usb4". When present, > > the PS883x driver rejects USB4 mode (-EOPNOTSUPP). This forces the > > Type-C stack to fall back to USB3 + DP Alt Mode, which works > > reliably with the 40B0. > > > > - Refactor DP altmode handling to also support the legacy > > TYPEC_DP_STATE_F request (deprecated since DP Alt Mode 1.0b) sent by > > the 40B0 and other docks (e.g. SSK SC220). > > > > - Add a short delay after writing configuration registers, which > > improves hotplug reliability. > > > > This is a temporary workaround until full USB4 DP tunneling support is > > available in the X1E USB4 controller and qmp-combo PHY stack. > > > > Note: The DT patch adds the new property to all currently upstream > > boards using the PS883x retimer (15 files). Happy to split it on v2 > > if requested. > > I don't think a kernel driver limitation is a good reason for the DT > property. I suggest to add something like this in the ps883x driver > instead: > > /* > * Hamoa does not yet support USB4, disable it for now to gracefully > * fall back to USB3 + DP AltMode. This should be removed once USB4 > * support landed for X1E. > */ > if (of_machine_is_compatible("qcom,x1e80100")) > disable_usb4 = true; It seems a bit of a weird abstraction break to put a machine type check down in a device that's not specific to qcom. I'd bet it's not just qcom's suffering from this as well. Dave > Greetings, > > -- Sebastian > > > As an additional observation, the same dock with type-c cable works well > > on Thinkpad X13s, Thinkbook 16 G7 QOY, Ideapad 5 14Q8X9, but doesn't need > > the ps883x changes (naturally). > > > > Signed-off-by: Jens Glathe > > --- > > Jens Glathe (5): > > dt-bindings: usb: parade,ps8830: Add parade,disable-usb4 property > > usb: typec: ps883x: Return -EOPNOTSUPP for USB4 when parade,disable-usb4 is set > > usb: typec: mux: ps883x: refactor DP altmode handling and support TYPEC_DP_STATE_F > > usb: typec: mux: ps883x: add a delay after writing config regs > > arm64: dts: qcom: x1: disable ps883x USB4 capability > > > > .../devicetree/bindings/usb/parade,ps8830.yaml | 6 +++ > > arch/arm64/boot/dts/qcom/hamoa-iot-evk.dts | 4 ++ > > .../qcom/hamoa-lenovo-ideacentre-mini-01q8x10.dts | 2 + > > arch/arm64/boot/dts/qcom/purwa-iot-evk.dts | 6 +++ > > arch/arm64/boot/dts/qcom/x1-asus-vivobook-s15.dtsi | 4 ++ > > arch/arm64/boot/dts/qcom/x1-asus-zenbook-a14.dtsi | 4 ++ > > arch/arm64/boot/dts/qcom/x1-crd.dtsi | 6 +++ > > arch/arm64/boot/dts/qcom/x1-dell-thena.dtsi | 4 ++ > > arch/arm64/boot/dts/qcom/x1-hp-omnibook-x14.dtsi | 2 + > > arch/arm64/boot/dts/qcom/x1-microsoft-denali.dtsi | 4 ++ > > arch/arm64/boot/dts/qcom/x1e001de-devkit.dts | 6 +++ > > .../dts/qcom/x1e78100-lenovo-thinkpad-t14s.dtsi | 4 ++ > > .../boot/dts/qcom/x1e80100-dell-xps13-9345.dts | 4 ++ > > .../boot/dts/qcom/x1e80100-lenovo-yoga-slim7x.dts | 6 +++ > > .../dts/qcom/x1e80100-medion-sprchrgd-14-s1.dts | 2 + > > .../boot/dts/qcom/x1e80100-microsoft-romulus.dtsi | 4 ++ > > drivers/usb/typec/mux/ps883x.c | 47 +++++++++++++++------- > > 17 files changed, 100 insertions(+), 15 deletions(-) > > --- > > base-commit: 0718283ab28bc3907e10b61a6b4be6fefa1cbb2f > > change-id: 20260718-ps883x-disable-usb4-19b0fc13b5ab > > > > Best regards, > > -- > > Jens Glathe > > > > > > -- -----Open up your eyes, open up your mind, open up your code ------- / Dr. David Alan Gilbert | Running GNU/Linux | Happy \ \ dave @ treblig.org | | In Hex / \ _________________________|_____ http://www.treblig.org |_______/