From mboxrd@z Thu Jan 1 00:00:00 1970 From: Lukasz Majewski Subject: Re: [PATCH 3/3] thermal: core: fix: Check return code of the ->get_max_state() callback Date: Fri, 03 Oct 2014 12:40:54 +0200 Message-ID: <20141003124054.404ac26c@amdc2363> References: <1411547232-21493-1-git-send-email-l.majewski@samsung.com> <1411547232-21493-4-git-send-email-l.majewski@samsung.com> <20141002222441.GA11510@developer> Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Return-path: Received: from mailout4.samsung.com ([203.254.224.34]:12322 "EHLO mailout4.samsung.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750852AbaJCKlX (ORCPT ); Fri, 3 Oct 2014 06:41:23 -0400 In-reply-to: <20141002222441.GA11510@developer> Sender: linux-pm-owner@vger.kernel.org List-Id: linux-pm@vger.kernel.org To: Eduardo Valentin , Zhang Rui Cc: Linux PM list , Lukasz Majewski , Bartlomiej Zolnierkiewicz , linux-kernel@vger.kernel.org Hi Eduardo, Rui, > On Wed, Sep 24, 2014 at 10:27:12AM +0200, Lukasz Majewski wrote: > > Without this check it was possible to execute cooling device > > binding code even when wrong max cooling state was read. > > > > Signed-off-by: Lukasz Majewski > > Acked-by: Eduardo Valentin > > Rui, are you taking these patches? Do you prefer me to collect them? I'd like to ask you NOT to apply those patches. In short: It will cause regression on all non Exynos boards. Explanation: Up till now the cpu_cooling device was bind even when the get_max_state() returned -EINVAL and everything worked after late cpufreq policy initialization. However, during this time window the thermal driver is not properly configured. Applying PATCH2/3 and PATCH3/3 would cause bind error without any further occasion for re-bind. As a result THERAL will not be present on the target system. It works on the Exynos boards, since at the report_trigger() function, when first trip point is reached, it is checked if cpu_cooling device is bind. If it is not (due to "fixes" at PATCH2/3 and PATCH3/3) it is rebind then. Due to above, I think that it would be best to leave things as they are now and prepare proper fix as suggested by Eduardo. > > Cheers > > Eduardo > > > --- > > drivers/thermal/thermal_core.c | 6 ++++-- > > 1 file changed, 4 insertions(+), 2 deletions(-) > > > > diff --git a/drivers/thermal/thermal_core.c > > b/drivers/thermal/thermal_core.c index 747618a..8a4dc35 100644 > > --- a/drivers/thermal/thermal_core.c > > +++ b/drivers/thermal/thermal_core.c > > @@ -928,7 +928,7 @@ int thermal_zone_bind_cooling_device(struct > > thermal_zone_device *tz, struct thermal_zone_device *pos1; > > struct thermal_cooling_device *pos2; > > unsigned long max_state = 0; > > - int result; > > + int result, ret; > > > > if (trip >= tz->trips || (trip < 0 && trip != > > THERMAL_TRIPS_NONE)) return -EINVAL; > > @@ -945,7 +945,9 @@ int thermal_zone_bind_cooling_device(struct > > thermal_zone_device *tz, if (tz != pos1 || cdev != pos2) > > return -EINVAL; > > > > - cdev->ops->get_max_state(cdev, &max_state); > > + ret = cdev->ops->get_max_state(cdev, &max_state); > > + if (ret) > > + return ret; > > > > /* lower default 0, upper default max_state */ > > lower = lower == THERMAL_NO_LIMIT ? 0 : lower; > > -- > > 2.0.0.rc2 > > -- Best regards, Lukasz Majewski Samsung R&D Institute Poland (SRPOL) | Linux Platform Group