From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mgamail.intel.com (mgamail.intel.com [192.198.163.8]) (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 481355427F9; Tue, 22 Sep 2026 12:28:26 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=192.198.163.8 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1790080108; cv=none; b=hZItHC29q9SxtZO1jaJUlwzEn9WimZZ94FB7dB9hnT46eIDNaYiv3kQ4u2ALlzdH/HJE9a92w847WC1f7VANRp8XSxwS4baYZHI4Dl8GWqJwDrnn17NOgSoS9tDkjLoiizycYn5bia8pajXL9IpnBP30bMhI3b7/g31Ho9bqkfA= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1790080108; c=relaxed/simple; bh=EWY9Bvnz8rYWx3ifpprjhjFA3DIBpRife5PllKzgFkU=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=GwDei5O2MMQi9mg+puv77jFBC95ZnzRDG+a3bgHa5cPQAbgVeBve/btab+Kyk69tZNdWbWEs/ldQqYCePf7mq7CidjMCN+Qm1+f2W5QKv1MLl9aQPkXvOnlBM9xOv9MJsV+tm9DirOudwG7gMC+GL+gCdD+u3A/8OiZ04PL8edg= 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=Q+2yrDeJ; arc=none smtp.client-ip=192.198.163.8 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="Q+2yrDeJ" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1790080106; x=1821616106; h=date:from:to:cc:subject:message-id:references: mime-version:in-reply-to; bh=EWY9Bvnz8rYWx3ifpprjhjFA3DIBpRife5PllKzgFkU=; b=Q+2yrDeJ4Cobb7GKAnbsaizErEIA6b+gu8/ypzYCfbgNM4fjk2FnlOCX 8HYg3gjdB3d6XXHHXUfExMssdSloeHEHz0qA4s+70kjVhIOZHOYOziP0Y CXqY1xToGdR1+Oo/wUe5RY9sodbAHWd2fAnh8WPb/AWPWwsapRjg44Ozy 4aEUHPga1vF2zjs3tDcF4gCrv/GlnwDQb68gfNdme8Nv4xAJg4UYshWOD rN5T3tiODiSGPuQhQm2bywCGe93Qvdo0SyakWYAoVdKqr5j2kLDJG+j2c 5/jMD1THuEosM3IYjf1h9Nk47SFHeAZGwTVxfpaq7MvNVMYOaEOUwSNrg Q==; X-CSE-ConnectionGUID: um6dUMjHSSKaEfMfSQoJ7A== X-CSE-MsgGUID: eyV7aLxGQ/WIvJEoSNl00g== X-IronPort-AV: E=McAfee;i="6800,10657,11912"; a="108175236" X-IronPort-AV: E=Sophos;i="6.27,116,1787036400"; d="scan'208";a="108175236" Received: from fmviesa005.fm.intel.com ([10.60.135.145]) by fmvoesa102.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 22 Sep 2026 05:28:25 -0700 X-CSE-ConnectionGUID: MSjZ7MenTlKCG44pM6XfDA== X-CSE-MsgGUID: 9XqblcrdRCOZIhU9GkIf0Q== X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="6.27,116,1787036400"; d="scan'208";a="281172922" Received: from black.igk.intel.com ([10.91.253.5]) by fmviesa005.fm.intel.com with ESMTP; 22 Sep 2026 05:28:23 -0700 Received: by black.igk.intel.com (Postfix, from userid 1008) id 3026C99; Tue, 22 Sep 2026 14:28:17 +0200 (CEST) Date: Tue, 22 Sep 2026 14:28:17 +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 v4 2/3] usb: typec: mux: ps883x: add a delay after writing config regs Message-ID: References: <20260922-ps883x-disable-usb4-v4-0-0a7b5b70cba3@oldschoolsolutions.biz> <20260922-ps883x-disable-usb4-v4-2-0a7b5b70cba3@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: <20260922-ps883x-disable-usb4-v4-2-0a7b5b70cba3@oldschoolsolutions.biz> On Tue, Sep 22, 2026 at 02:20:20PM +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