From mboxrd@z Thu Jan 1 00:00:00 1970 From: "Rafael J. Wysocki" Subject: Re: [PATCH 0/2][RFC] PM / sleep: Expose DPM watchdog timeout to sysfs Date: Fri, 12 Aug 2016 13:25:04 +0200 Message-ID: References: <20160811185441.GA15813@amd> <20160812025225.GA12238@sharon> <20160812063312.GD30992@amd> Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Return-path: Received: from mail-wm0-f68.google.com ([74.125.82.68]:36780 "EHLO mail-wm0-f68.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752902AbcHLLZH (ORCPT ); Fri, 12 Aug 2016 07:25:07 -0400 Received: by mail-wm0-f68.google.com with SMTP id i138so2284355wmf.3 for ; Fri, 12 Aug 2016 04:25:06 -0700 (PDT) In-Reply-To: <20160812063312.GD30992@amd> Sender: linux-pm-owner@vger.kernel.org List-Id: linux-pm@vger.kernel.org To: Pavel Machek Cc: Chen Yu , Linux PM List , "Rafael J. Wysocki" , Greg Kroah-Hartman , Len Brown , Takashi Iwai , Benoit Goby On Fri, Aug 12, 2016 at 8:33 AM, Pavel Machek wrote: > Hi! > >> > > Recently we have a new report that, the harddisk can not >> > > resume on time due to firmware issues, and got a kernel >> > > panic because of DPM watchdog timeout. Since the default >> > > timeout has once been modified from 12 to 60 seconds, we >> > > might still encounter new case which requires a longer timeout, >> > > so expose the value to sysfs and let the users decide which >> > > value is appropriate, meanwhile this can also ease the debugging >> > > process. >> > > >> > > The first patch is to force DPM watchdog depending on CONFIG_PM_SLEEP, >> > > thus the second patch which does the actual work, can use >> > > CONFIG_DPM_WATCHDOG safely without checking CONFIG_PM_SLEEP. >> > >> > Kernel should just work. User should not have to configure random >> > knobs to have working suspend/hibernation. >> > >> > We do not want "CONFIG_BREAK_SUSPEND" so I believe we don't want >> > "CONFIG_DPM_WATCHDOG". If normal users select it and it breaks their >> > system, make it depend on "CONFIG_EXPERT" or hide it in some other >> > way or maybe remove it from Kconfig altogether. >> > >> > Or maybe CONFIG_DPM_WATCHDOG should contain numeric value that user >> > has to select? >> > >> Yes, if people select it then they have the risk to break their system, >> and the original thought of the patch is to behave like a diagnosis to >> make it easier for the users to figure it out, how much time it takes >> to suspend/resume a bogus peripheral, without recomping the kernel. >> -- currently the timeout value for CONFIG_DPM_WATCHDOG can be adjusted >> by menuconfig, but bug reporter might have to recompile the kernel >> to confirm, and it takes some time to get a feedback from them, so... > > Please don't add sysfs knobs for this. People should not need to > adjust sysfs files to get working kernel. > > You can for example make the default 120 seconds. Plus, IMO it would be good to be able to disable this thing from the kernel command line entirely in case 2 minutes is still too little time for somebody. Thanks, Rafael