From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mgamail.intel.com (mgamail.intel.com [192.198.163.17]) (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 B2DBC43E083; Fri, 18 Sep 2026 09:56:05 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=192.198.163.17 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1789725367; cv=none; b=EJHi0N+8xOOCYy1opQ7rxFGIbIM4PVJE/Sq1fHjhDpugx+IKuXpK1qgQSuZopsawTXuZaMWV7oKeYeXBwOVAZeLnITn8Y0g4F9m2CJDgdCAMI07FyWiseWZDm04jwqHJYwsKcNmtynzu0KYE7fRl6QNz4kxIrR0QOvxpWPp2aZY= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1789725367; c=relaxed/simple; bh=A/ox7ZE4vAif5kQLQDU5rNYE23M1iB2N/MfTE9UgpC0=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=o0+r3KfsXmDMnCIeB3kM1zfkQzkHiaKZS3XWMBHWuijrfj6zW7jBwI6Uc3iNSK+yMC3m1TkxgNDO1WiFo3n2EAfmwmFs85fJYCEw1SGZWt5J9+KXdTocchErZ2V8DN8N4dZFJ/6fT1oYv/dXCp0yJCOqsK/a/q8L/9+NnjqCC1w= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.intel.com; spf=pass smtp.mailfrom=linux.intel.com; dkim=pass (2048-bit key) header.d=intel.com header.i=@intel.com header.b=F0VnkkiP; arc=none smtp.client-ip=192.198.163.17 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.intel.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=linux.intel.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=intel.com header.i=@intel.com header.b="F0VnkkiP" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1789725365; x=1821261365; h=date:from:to:cc:subject:message-id:references: mime-version:in-reply-to; bh=A/ox7ZE4vAif5kQLQDU5rNYE23M1iB2N/MfTE9UgpC0=; b=F0VnkkiPtN8EHy9DG9gk0POzCVvZvrS/B+WqWOwoRUWlDFByWfMw6og9 hvMybrr7DbvmpAlEok6YMIGVgsPk4rxsMGZp2cVJg2nq3fBcmEewtWkAD HHxtDVrrjccs7wxMvZ4obPWJeiTBIv20VHogugnSII5YwBsqhfBxadvMj mP0BvcrIK2loXosFBfbyH34MOiZxM0ONwAHvAGi1uPLLH65T+WDk0G7p6 W+xJBctOn0g45Xyl79tTx7tDWF8YgPFBpT3KlqJ9iZu78xZnowvI+BXR8 kddQHK1qlLlyNXHRUV6lv0OmShcU4X7Vx4j/Lz2ozpG1PYYU9d+TI/UUK w==; X-CSE-ConnectionGUID: 2/DwYilwREOrlLudFNUKwQ== X-CSE-MsgGUID: jibyqViZR/ORdUhKU0JWBw== X-IronPort-AV: E=McAfee;i="6800,10657,11905"; a="90086143" X-IronPort-AV: E=Sophos;i="6.27,103,1787036400"; d="scan'208";a="90086143" Received: from fmviesa009.fm.intel.com ([10.60.135.149]) by fmvoesa111.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 18 Sep 2026 02:56:05 -0700 X-CSE-ConnectionGUID: Qe9lG5lCTqyz1vefHD97TQ== X-CSE-MsgGUID: 7mJg3ctFQcOJJehiRT7oHw== X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="6.27,103,1787036400"; d="scan'208";a="268067818" Received: from black.igk.intel.com ([10.91.253.5]) by fmviesa009.fm.intel.com with ESMTP; 18 Sep 2026 02:56:01 -0700 Received: by black.igk.intel.com (Postfix, from userid 1008) id 6902A99; Fri, 18 Sep 2026 11:55:57 +0200 (CEST) Date: Fri, 18 Sep 2026 11:55:57 +0200 From: Heikki Krogerus To: jens.glathe@oldschoolsolutions.biz Cc: Greg Kroah-Hartman , Abel Vesa , Bjorn Andersson , Konrad Dybcio , Sebastian Reichel , linux-usb@vger.kernel.org, linux-kernel@vger.kernel.org, linux-arm-msm@vger.kernel.org, stable@vger.kernel.org, "Dr. David Alan Gilbert" , Dmitry Baryshkov Subject: Re: [PATCH v3 2/3] usb: typec: mux: ps883x: add a delay after writing config regs Message-ID: References: <20260916-ps883x-disable-usb4-v3-0-8f19386456d0@oldschoolsolutions.biz> <20260916-ps883x-disable-usb4-v3-2-8f19386456d0@oldschoolsolutions.biz> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20260916-ps883x-disable-usb4-v3-2-8f19386456d0@oldschoolsolutions.biz> On Wed, Sep 16, 2026 at 09:36:33PM +0200, Jens Glathe via B4 Relay wrote: > From: Jens Glathe > > The connection-status registers need time to propagate through the > analog front-end (PLLs, lane training) after they are written. A 30 ms > delay after ps883x_configure() brings DisplayPort Alt Mode hotplug on > the Lenovo 40B0 to a reliable success rate. > > Tested with T14s G6 and IdeaCentre Mini with the 40B0 dock on the HDMI > port with a Type-C host cable. Qualcomm firmware that programs this > retimer from an MCU uses a similar post-config delay. > > Assisted-by: Grok(xAI):4.6 > Signed-off-by: Jens Glathe Acked-by: Heikki Krogerus > --- > drivers/usb/typec/mux/ps883x.c | 10 ++++++++++ > 1 file changed, 10 insertions(+) > > diff --git a/drivers/usb/typec/mux/ps883x.c b/drivers/usb/typec/mux/ps883x.c > index a5696aef054ee..15aee1d613b1a 100644 > --- a/drivers/usb/typec/mux/ps883x.c > +++ b/drivers/usb/typec/mux/ps883x.c > @@ -7,6 +7,7 @@ > > #include > #include > +#include > #include > #include > #include > @@ -184,6 +185,15 @@ static int ps883x_configure(struct ps883x_retimer *retimer, int cfg0, > return ret; > } > > + /* > + * The retimer needs time after the connection-status registers are > + * written for the analog front-end (PLLs, lane training) to settle. > + * Without this, DisplayPort Alt Mode hotplug is unreliable on some > + * docks (e.g. Lenovo 40B0). Qualcomm firmware on platforms that > + * program this chip from an MCU uses a similar post-config delay. > + */ > + fsleep(30000); > + > return 0; > } > > > -- > 2.53.0 > -- heikki