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 D900EC433EF for ; Mon, 20 Dec 2021 15:51:56 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S237014AbhLTPvz (ORCPT ); Mon, 20 Dec 2021 10:51:55 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:49406 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231790AbhLTPvy (ORCPT ); Mon, 20 Dec 2021 10:51:54 -0500 Received: from desiato.infradead.org (desiato.infradead.org [IPv6:2001:8b0:10b:1:d65d:64ff:fe57:4e05]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 731E8C061574; Mon, 20 Dec 2021 07:51:54 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=desiato.20200630; h=In-Reply-To:Content-Type:MIME-Version: References:Message-ID:Subject:Cc:To:From:Date:Sender:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description; bh=p6oI7t6a2sP+y+8OnSAo1gKUw6uZD1Gb+30mWCzcviM=; b=TbrO5EIrYsdS1CZXyeUMFR1ZGj igJHlz87ytOr2HT8Scqbk1ZenaFxBIoXwSi/zvAsHkk2d+ZJQ3j0GMVjUdHheawHIz0wKzkFoHyiG T9ZHq9vF1RZ88SgZGZTR8mq0EeULOXJ71RFoWcYTDG4oaBS0c6lOkXXiM3aNnhTAOJ58QlcfngYnQ Ea2XeVCuz89bpJIiroPXhTK2X+LOL1fEazLkOK/y6+b8DXbmPHOum4l5JQIWZP62lH/zC10eCMSP0 2J5tqVGEwSetWQTvxHD3/yoqJAKxMFPvuFyZphCUbyDzbwXL51E8KmL9GfZmTaSwL/12WQvi24R9n OzAToDKQ==; Received: from j217100.upc-j.chello.nl ([24.132.217.100] helo=noisy.programming.kicks-ass.net) by desiato.infradead.org with esmtpsa (Exim 4.94.2 #2 (Red Hat Linux)) id 1mzKww-002X19-7X; Mon, 20 Dec 2021 15:51:42 +0000 Received: from hirez.programming.kicks-ass.net (hirez.programming.kicks-ass.net [192.168.1.225]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (4096 bits) server-digest SHA256) (Client did not present a certificate) by noisy.programming.kicks-ass.net (Postfix) with ESMTPS id 0F38530003C; Mon, 20 Dec 2021 16:51:40 +0100 (CET) Received: by hirez.programming.kicks-ass.net (Postfix, from userid 1000) id AB011200E706A; Mon, 20 Dec 2021 16:51:40 +0100 (CET) Date: Mon, 20 Dec 2021 16:51:40 +0100 From: Peter Zijlstra To: Mathias Nyman Cc: Greg KH , Dave Hansen , Lu Baolu , x86@kernel.org, linux-kernel@vger.kernel.org, linux-usb@vger.kernel.org, Chunfeng Yun Subject: Re: earlyprintk=xdbc seems broken Message-ID: References: <105f35d2-3c53-b550-bfb4-aa340d31128e@linux.intel.com> <88f466ff-a065-1e9a-4226-0abe2e71b686@linux.intel.com> <972a0e28-ad63-9766-88da-02743f80181b@intel.com> <3281618b-64df-711e-4360-c74e6165d7ed@linux.intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <3281618b-64df-711e-4360-c74e6165d7ed@linux.intel.com> Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, Dec 20, 2021 at 04:34:13PM +0200, Mathias Nyman wrote: > On 17.12.2021 15.55, Peter Zijlstra wrote: > > On Fri, Dec 17, 2021 at 01:01:43PM +0200, Mathias Nyman wrote: > >> I can reproduce this. > >> Looks like problems started when driver converted to readl_poll_timeout_atomic() in: > >> > >> 796eed4b2342 usb: early: convert to readl_poll_timeout_atomic() > > > > I can confirm, reverting that solves the boot hang, things aren't quite > > working for me though. > > > >> Seems to hang when read_poll_timeout_atomic() calls ktime_* functions. > >> Maybe it's too early for ktime. > > > > It certainly is, using ktime for delay loops sounds daft to me anyhow. > > > >> After reverting that patch it works again for me. > > > > [ 0.000000] Command line: BOOT_IMAGE=/boot/vmlinuz-5.16.0-rc3+ root=UUID=a652986c-fbc6-4341-85c3-b4ad4402f130 ro debug ignore_loglevel sysrq_always_enabled usbcore.autosuspend=-1 earlyprintk=xdbc force_early_printk sched_verbose ftrace=nop mitigations=off nokaslr > > ... > > [ 0.000000] xhci_dbc:early_xdbc_parse_parameter: dbgp_num: 0 > > ... > > [ 3.161367] xhci_dbc:early_xdbc_setup_hardware: failed to setup the connection to host > > Ok, this is some other issue. I got the boot messages over USB > (running minicom at the other end, listening to ttyUSB0) I have a regular A->A USB3 cable, not the special one with a wire missing. Given the dbc thing works, I feel this ought to work too. > > The machine does boot.. but I *am* getting tons of: > > > > [ 485.546898] usb usb4-port4: Cannot enable. Maybe the USB cable is bad? > > [ 485.546963] usb usb4-port4: config error > > This is expected when xhci driver takes over after the early dbc driver, > xhci driver resets xHC controller, and all ports turn to normal host ports again. > > Because of the special cable you now have two hosts connected to each other, > both trying to enumerate a device. > > This whole transition from earlyprintk xdbc to normal xhci driver is > not very userfriendly. Uhhmm... but but that shouldn't be. What if I want to keep using xdbc as console after that point? specifically, I'll probably end up having: earlyprintk=xdbc,keep once all this starts working. The whole point of early consoles is that they're more reliable than regular consoles, not that they're 'early'. > > However, when I do: > > > > $ echo enable > /sys/bus/pci/devices/0000:00:14.0/dbc > > > > Yes, this works as it turns on the DbC feature on in xHC hardware, > which turns the first USB port into a usb device. But if this works, why isn't earlyprintk working for me?