From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from smtp1.linuxfoundation.org (smtp1.linux-foundation.org [172.17.192.35]) by mail.linuxfoundation.org (Postfix) with ESMTPS id 6C4417A9 for ; Thu, 19 Oct 2017 08:55:44 +0000 (UTC) Received: from mail-io0-f182.google.com (mail-io0-f182.google.com [209.85.223.182]) by smtp1.linuxfoundation.org (Postfix) with ESMTPS id BEAAE488 for ; Thu, 19 Oct 2017 08:55:43 +0000 (UTC) Received: by mail-io0-f182.google.com with SMTP id 101so9088216ioj.3 for ; Thu, 19 Oct 2017 01:55:43 -0700 (PDT) MIME-Version: 1.0 In-Reply-To: <1647817.aU4A16bmHW@aspire.rjw.lan> References: <1647817.aU4A16bmHW@aspire.rjw.lan> From: Ulf Hansson Date: Thu, 19 Oct 2017 10:55:42 +0200 Message-ID: To: "Rafael J. Wysocki" Content-Type: text/plain; charset="UTF-8" Cc: Greg Kroah-Hartman , "ksummit-discuss@lists.linuxfoundation.org" Subject: Re: [Ksummit-discuss] [TECH TOPIC] Device power management during system-wide PM transitions List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , On 18 October 2017 at 13:17, Rafael J. Wysocki wrote: > Hi, > > If this isn't too late, I'd like to put a PM topic on the agenda. > > One problem basically is that runtime PM interacts with system-wide PM for > devices in ways that need to be taken care of. The most common patterns are: > > - What if a device is in runtime suspend before system suspend? Can it > remain suspended and under what conditions if so? > > - Can devices be left in suspend when the system is resuming from > system-wide suspend? > > - Can driver runtime PM callbacks be used for system-wide PM too and to > what extent? If they can, how to make that happen? > > We have tried to address these points in a couple of different ways so > far, but none of them is universal enough. Moreover, one approach is > mostly for systems with PCI/ACPI and the other one is used on systems > without those and they both are not compatible. That sort of didn't > matter until IP block sharing between vendors led to situations in > which one and the same driver is expected to work in both environments. > > It would be good to have a common approach and IMO it should be based on > changing the PM core to help address the most common cases, so I posted > a set of patches to that end: > > https://marc.info/?l=linux-kernel&m=150811822405206&w=2 > > and I'd like to have a discussion regarding that and it spans many > different subsystems potentially, so the KS seems to be the right venue > for that discussion to happen. > > The second issue is that some bus types and quite a few drivers still use > legacy power management callbacks and I'd like to get rid of those at last, > first from the bus types and then from drivers too. That's more of a > heads-up thing, but also possibly touches multiple places, so should be > suitable for a KS session as well. > > Thanks, > Rafael > Rafael, thanks for suggesting this topic, of course I share your interest in discussion this in Prague. Kind regards Uffe