From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S933970AbeEWR7d (ORCPT ); Wed, 23 May 2018 13:59:33 -0400 Received: from muru.com ([72.249.23.125]:44188 "EHLO muru.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S933936AbeEWR7D (ORCPT ); Wed, 23 May 2018 13:59:03 -0400 Date: Wed, 23 May 2018 10:58:59 -0700 From: Tony Lindgren To: Andy Shevchenko Cc: Andy Shevchenko , Sebastian Andrzej Siewior , Petr Mladek , Sergey Senozhatsky , Steven Rostedt , Linux Kernel Mailing List , Greg Kroah-Hartman , Jiri Slaby , "open list:SERIAL DRIVERS" , Arnd Bergmann Subject: Re: [PATCH v1 0/3] console, serial8250: Disable PM and DMA ops Message-ID: <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> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.9.4 (2018-02-28) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org * 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. > > 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 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? :) > >> 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 with no regressions. Regards, TOny