From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753899AbdGNKbV (ORCPT ); Fri, 14 Jul 2017 06:31:21 -0400 Received: from foss.arm.com ([217.140.101.70]:46898 "EHLO foss.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753808AbdGNKbU (ORCPT ); Fri, 14 Jul 2017 06:31:20 -0400 Cc: Sudeep Holla , "linux-pm@vger.kernel.org" , "linux-kernel@vger.kernel.org" , "Rafael J. Wysocki" , Kevin Hilman Subject: Re: [PATCH] PM / Domains: defer dev_pm_domain_set() until genpd->attach_dev succeeds if present To: Ulf Hansson References: <1498759251-11709-1-git-send-email-sudeep.holla@arm.com> From: Sudeep Holla Organization: ARM Message-ID: <0a29eebd-5e52-2cf2-b264-0f8187c590f9@arm.com> Date: Fri, 14 Jul 2017 11:31:16 +0100 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:52.0) Gecko/20100101 Thunderbird/52.2.1 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 12/07/17 17:36, Sudeep Holla wrote: > > > On 12/07/17 14:59, Ulf Hansson wrote: >> On 29 June 2017 at 20:00, Sudeep Holla wrote: >>> If the genpd->attach_dev or genpd->power_on fails, genpd_dev_pm_attach >>> may return -EPROBE_DEFER initially. However genpd_alloc_dev_data sets >>> the PM domain for the device unconditionally. >>> >>> When subsequent attempts are made to call genpd_dev_pm_attach, it may >>> return -EEXISTS checking dev->pm_domain without re-attempting to call >>> attach_dev or power_on. >>> >>> platform_drv_probe then attempts to call drv->probe as the return value >>> -EEXIST != -EPROBE_DEFER, which may end up in a situation where the >>> device is accessed without it's power domain switched on. >> >> Right, this makes sense. >> > > Thanks > >>> >>> Cc: "Rafael J. Wysocki" >>> Cc: Kevin Hilman >>> Cc: Ulf Hansson >>> Signed-off-by: Sudeep Holla >> >> Could we perhaps work out which commit it fixes, or perhaps the >> problem been there long time ago and we should just add a stable tag? >> > > OK I will dig that out. > It looks like commit 989561de9b51 ("PM / Domains: add setter for dev.pm_domain") added the helper. I then follow it to commit f104e1e5ef57 ("PM / Domains: Re-order initialization of generic_pm_domain_data"). The code in the original commit 6ff7bb0d02f8 ("PM / Domains: Cache device stop and domain power off governor results, v3") looks OK to me. So What should I do ? Add Fixes: f104e1e5ef57 ("PM / Domains: Re-order initialization of generic_pm_domain_data") tag in the mainline. And when Greg or others fix up before v4.4, I need to work out the fix for that stable version ? -- Regards, Sudeep