From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 6E012C433FE for ; Fri, 3 Dec 2021 00:53:01 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S240208AbhLCA4X (ORCPT ); Thu, 2 Dec 2021 19:56:23 -0500 Received: from mga01.intel.com ([192.55.52.88]:47802 "EHLO mga01.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232416AbhLCA4W (ORCPT ); Thu, 2 Dec 2021 19:56:22 -0500 X-IronPort-AV: E=McAfee;i="6200,9189,10186"; a="260883577" X-IronPort-AV: E=Sophos;i="5.87,283,1631602800"; d="scan'208";a="260883577" Received: from orsmga008.jf.intel.com ([10.7.209.65]) by fmsmga101.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 02 Dec 2021 16:52:58 -0800 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.87,283,1631602800"; d="scan'208";a="513459179" Received: from allen-box.sh.intel.com (HELO [10.239.159.118]) ([10.239.159.118]) by orsmga008.jf.intel.com with ESMTP; 02 Dec 2021 16:52:56 -0800 Cc: baolu.lu@linux.intel.com, x86@kernel.org, linux-kernel@vger.kernel.org, gregkh@linuxfoundation.org, linux-usb@vger.kernel.org Subject: Re: earlyprintk=xdbc seems broken To: Peter Zijlstra , Mathias Nyman References: From: Lu Baolu Message-ID: <105f35d2-3c53-b550-bfb4-aa340d31128e@linux.intel.com> Date: Fri, 3 Dec 2021 08:52:53 +0800 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:78.0) Gecko/20100101 Thunderbird/78.14.0 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi Peter, On 12/2/21 11:22 PM, Peter Zijlstra wrote: > Hi Lu, > > I was unfortunate enough to need xdbc and can't get my machine to boot > with earlyprintk=xdbc on the cmdline. > > When I boot the target without the earlyprintk=xdbc, but have the cable > attached, it won't boot because boot gets stuck like: > > Dec 2 15:08:10 tigerlake kernel: [ 42.043137] usb usb4-port3: Cannot enable. Maybe the USB cable is bad? > Dec 2 15:08:10 tigerlake kernel: [ 42.043227] usb usb4-port3: config error > > However, when I boot without earlyprintk=xdbc, without the cable > attached, then I can attach the cable and: > > $ echo enable > /sys/bus/pci/devices/0000:00:14.0/dbc > > will actually work, and it shows up on my host system: > > [1023855.419430] usb usb2-port3: Cannot enable. Maybe the USB cable is bad? > [1023855.419455] usb usb2-port3: config error > [1023859.491476] usb usb2-port3: Cannot enable. Maybe the USB cable is bad? > [1023859.491487] usb usb2-port3: config error > [1023861.335436] usb usb2-port3: config error > [1023861.607476] usb 2-3: new SuperSpeed USB device number 7 using xhci_hcd > [1023861.627614] usb 2-3: LPM exit latency is zeroed, disabling LPM. > [1023861.627853] usb 2-3: New USB device found, idVendor=1d6b, idProduct=0010, bcdDevice= 0.10 > [1023861.627855] usb 2-3: New USB device strings: Mfr=1, Product=2, SerialNumber=3 > [1023861.627856] usb 2-3: Product: Linux USB Debug Target > [1023861.627857] usb 2-3: Manufacturer: Linux Foundation > [1023861.627858] usb 2-3: SerialNumber: 0001 > [1023861.629344] usb_debug 2-3:1.0: xhci_dbc converter detected > [1023861.629532] usb 2-3: xhci_dbc converter now attached to ttyUSB0 > > > Can you please see if you can repro and fix this? > > This all was with current 5.16-rc3 on a tigerlake nuc. > > Also, perhaps you can update the guide on what sort of setup/cables > etc.. you need when either the host or the client is a usb3.1 usb-c only > device. > + Mathias, maybe he still has a USB 3.0 debugging cable. Best regards, baolu