From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753895AbdGLQgk (ORCPT ); Wed, 12 Jul 2017 12:36:40 -0400 Received: from foss.arm.com ([217.140.101.70]:56898 "EHLO foss.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753273AbdGLQgi (ORCPT ); Wed, 12 Jul 2017 12:36:38 -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: Date: Wed, 12 Jul 2017 17:36:35 +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 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. >> --- >> drivers/base/power/domain.c | 4 ++-- >> 1 file changed, 2 insertions(+), 2 deletions(-) >> >> diff --git a/drivers/base/power/domain.c b/drivers/base/power/domain.c >> index da49a8383dc3..b195d34de888 100644 >> --- a/drivers/base/power/domain.c >> +++ b/drivers/base/power/domain.c >> @@ -1168,8 +1168,6 @@ static struct generic_pm_domain_data *genpd_alloc_dev_data(struct device *dev, >> >> spin_unlock_irq(&dev->power.lock); >> >> - dev_pm_domain_set(dev, &genpd->domain); >> - >> return gpd_data; >> >> err_free: >> @@ -1221,6 +1219,8 @@ static int genpd_add_device(struct generic_pm_domain *genpd, struct device *dev, >> if (ret) >> goto out; >> >> + dev_pm_domain_set(dev, &genpd->domain); >> + >> genpd->device_count++; >> genpd->max_off_time_changed = true; >> >> -- >> 2.7.4 >> > > One piece is missing to make this fix complete. > > More precisely, you must also move the call to dev_pm_domain_set(dev, NULL). > Sure will add. > Currently that is done from genpd_free_dev_data(), as it corresponds > to genpd_alloc_dev_data(), but clearly the proper place to call it > should be from genpd_remove_device(). > OK, will also look into that. -- Regards, Sudeep