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=-0.8 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_PASS,URIBL_BLOCKED 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 89FF0ECDFBB for ; Wed, 18 Jul 2018 15:14:13 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 4EFFE20850 for ; Wed, 18 Jul 2018 15:14:13 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 4EFFE20850 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=linux.intel.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 S1731140AbeGRPwc (ORCPT ); Wed, 18 Jul 2018 11:52:32 -0400 Received: from mga03.intel.com ([134.134.136.65]:27294 "EHLO mga03.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726409AbeGRPwc (ORCPT ); Wed, 18 Jul 2018 11:52:32 -0400 X-Amp-Result: SKIPPED(no attachment in message) X-Amp-File-Uploaded: False Received: from orsmga006.jf.intel.com ([10.7.209.51]) by orsmga103.jf.intel.com with ESMTP/TLS/DHE-RSA-AES256-GCM-SHA384; 18 Jul 2018 08:14:10 -0700 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.51,370,1526367600"; d="scan'208";a="58668810" Received: from smile.fi.intel.com (HELO smile) ([10.237.72.86]) by orsmga006.jf.intel.com with ESMTP; 18 Jul 2018 08:14:04 -0700 Message-ID: Subject: Re: [PATCH v1 0/3] console, serial8250: Disable PM and DMA ops From: Andy Shevchenko To: Tony Lindgren , Andy Shevchenko Cc: Sebastian Andrzej Siewior , Petr Mladek , Sergey Senozhatsky , Steven Rostedt , Linux Kernel Mailing List , Greg Kroah-Hartman , Jiri Slaby , "open list:SERIAL DRIVERS" , Arnd Bergmann Date: Wed, 18 Jul 2018 18:14:03 +0300 In-Reply-To: <20180523175859.GO98604@atomide.com> References: <20180515183409.78046-1-andriy.shevchenko@linux.intel.com> <20180516100842.xuma7b3e727w7bpz@linutronix.de> <20180516104734.357oevogppu5bsg4@linutronix.de> <20180517135621.GJ98604@atomide.com> <20180517193008.GV25808@atomide.com> <20180523175859.GO98604@atomide.com> Organization: Intel Finland Oy Content-Type: text/plain; charset="UTF-8" X-Mailer: Evolution 3.28.1-2 Mime-Version: 1.0 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, 2018-05-23 at 10:58 -0700, Tony Lindgren wrote: > * Andy Shevchenko [180522 21:42]: > > On Thu, May 17, 2018 at 10:30 PM, Tony Lindgren > > wrote: > > > So how about add some "noidle" kernel command line parameter for > > > console > > > that calls > > > pm_runtime_forbid() and then you have the UART permanently > > > on. > > > > IIUC _forbid() can be overwritten via sysfs. > > And I would prefer to do other way around, something like > > console.idle > > and put default for OMAP to yes and no for everything else. > > OK yeah console.idle sounds good to me. We should default to a > safe option. I'll see what we can do here. > > > Hmm I guess you could make also serial8250_rpm_get() do nothing > > > based on that. > > > > Have you seen entire series which I keep here: > > https://bitbucket.org/andy-shev/linux/branch/topic/uart/rpm? > > Among other things it gets rid of those specific callbacks entirely. > > Well I was not Cc:ed on it, I browsed it in some archive and it > seemed unsafe to me. But if you figured out a way to do it > conditionally > based on console.idle > without causing regressions. I restored that branch with some updated patches. It's far from done and doesn't have any new stuff (yet) regrading to this discussion. > > > I do agree the serial runtime PM has an issue if it depends on > > > pm_runtime_irq_safe() being set. > > > > It's more than an issue. The so called "support" of RPM for UART is > > _based on the hack_. > > I would love to NAK that in the first place if I would have known of > > it in time. > > Hmm well it seems that you too have been patching the 8250_rpm > functions for years and then now what after multiple years you > hit this issue? :) Nope, I hit it as soon as I tried. I can't find easily the discussion (hmm... yes, I was so pissed off that time, I put a bit of harsh in that) I had with Sebastian few years back, but at least I reported about an issue. > > > > So, I can, of course just remove callbacks from the console > > > > ->write(). > > > > Though it will prevent to use kernel console anyway. > > > > > > Please et's not start breaking things, we already see a constant > > > flow of regressions on weekly basis. > > > > Now we are stick with a hack and the case based on that is against > > fixing things. > > This is how it looks from my side. > > Sorry yeah I agree there are issues, but let's fix it properly Agree. > with > no regressions. ...though I think a word "regression" is inappropriate here. Regression is what the support did in the first place. Pity I didn't know about it at that time. -- Andy Shevchenko Intel Finland Oy