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 X-Spam-Level: X-Spam-Status: No, score=-2.2 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_PASS,URIBL_BLOCKED,USER_AGENT_MUTT autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 32351C43143 for ; Mon, 1 Oct 2018 17:24:03 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id C2E362145D for ; Mon, 1 Oct 2018 17:24:02 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org C2E362145D Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=atomide.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726304AbeJBACs (ORCPT ); Mon, 1 Oct 2018 20:02:48 -0400 Received: from muru.com ([72.249.23.125]:57984 "EHLO muru.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725994AbeJBACs (ORCPT ); Mon, 1 Oct 2018 20:02:48 -0400 Received: from atomide.com (localhost [127.0.0.1]) by muru.com (Postfix) with ESMTPS id 26A0C80F0; Mon, 1 Oct 2018 17:28:26 +0000 (UTC) Date: Mon, 1 Oct 2018 10:23:57 -0700 From: Tony Lindgren To: Guenter Roeck Cc: Phil Edworthy , Greg KH , linux-kernel@vger.kernel.org, Andy Shevchenko Subject: Re: [PATCH] serial: 8250_dw: Fix runtime PM handling Message-ID: <20181001172356.GX5662@atomide.com> References: <20180928224056.GA10486@roeck-us.net> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20180928224056.GA10486@roeck-us.net> User-Agent: Mutt/1.10.1 (2018-07-13) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org * Guenter Roeck [180928 22:45]: > On Thu, May 10, 2018 at 03:13:56PM +0100, Phil Edworthy wrote: > > When using kgdb, you get an abort when accessing the UART registers. > > This is because the driver has already entered runtime PM and so turned > > off the bus clock needed to access the registers. > > > > To fix this, set the capability indicating Runtime PM is active while idle. > > > > With this patch applied, I get the already reported traceback [1]. > Obviously neither the promised revert [2] nor the presumed fix [3] made it > into the mainline Kernel. > > Greg, can you please revert this patch ? If people don't care enough > to fix the problem, we should at least not have to suffer the consequences. Yes please revert until things are fixed. FYI, what Andy and I discussed earlier is that we can disable runtime PM for serial layer by taking a PM runtime use count on the serial driver if there is an active console but we need a way to attach/detach kernel serial consoel via /sys to prevent regressions with PM. So how do we attach/detach kernel serial console? We don't seem to have a way to attach/detach a kernel console to a UART via /sys do we? Or am I again 10 years behind or something? We have /sys/class/vtconsole to bind and unbind a frame buffer console though. Andy, do you have your updated patches available somewhere? Regards, Tony > [1] https://www.spinics.net/lists/linux-serial/msg30379.html > [2] https://www.spinics.net/lists/linux-serial/msg30380.html > [3] https://www.spinics.net/lists/linux-serial/msg30757.html