From mboxrd@z Thu Jan 1 00:00:00 1970 From: Chanwoo Choi Subject: Re: [RFC PATCH] PM / devfreq: Add policy notifier Date: Fri, 18 May 2018 08:26:30 +0900 Message-ID: <5AFE0FA6.4020101@samsung.com> References: <20180515212447.180595-1-mka@chromium.org> <5AFCE27E.20803@samsung.com> <20180517230728.GQ19594@google.com> Mime-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 8BIT Return-path: In-reply-to: <20180517230728.GQ19594@google.com> Sender: linux-kernel-owner@vger.kernel.org To: Matthias Kaehlcke Cc: MyungJoo Ham , Kyungmin Park , linux-pm@vger.kernel.org, linux-kernel@vger.kernel.org, Brian Norris List-Id: linux-pm@vger.kernel.org Hi, On 2018년 05월 18일 08:07, Matthias Kaehlcke wrote: > Hi, > > On Thu, May 17, 2018 at 11:01:34AM +0900, Chanwoo Choi wrote: >> Hi, >> >> Could you give some use-case of DEVFREQ_POLICY_NOTIFIER >> or send use-case patch with this patch? > > This is a WIP patch that makes use of the DEVFREQ_POLICY_NOTIFIER: > > https://chromium-review.googlesource.com/c/chromiumos/third_party/kernel/+/1065122 > >> I already knew the CPUFREQ_POLICY_NOTIFIER. >> But, until now, there are no any requirements of DEVFREQ_POLICY_NOTIFIER. >> If there are no any use-case, it is not necessary codes. > > Sure, I intend to land the above driver upstream if devfreq can > provide the necessary interfaces. I recommend that you should send the patch with the use-case patch. > >> On 2018년 05월 16일 06:24, Matthias Kaehlcke wrote: >>> diff --git a/drivers/devfreq/devfreq.c b/drivers/devfreq/devfreq.c >>> index fe2af6aa88fc..a7294c056f65 100644 >>> --- a/drivers/devfreq/devfreq.c >>> +++ b/drivers/devfreq/devfreq.c >>> @@ -273,6 +273,9 @@ int update_devfreq(struct devfreq *devfreq) >>> if (err) >>> return err; >>> >>> + srcu_notifier_call_chain(&devfreq->policy_notifier_list, >>> + DEVFREQ_ADJUST, &freq); >> >> It is not proper to used 'freq' as the passed data. >> In current step,'freq' is not adjusted and is not final decided >> frequency. > > Right, the next revision will pass a struct devfreq_policy instead, > where the notifiers can adjust the min/max values, similar to what > cpufreq does. Actually, I don't know the devfreq_policy(?). As I already commented, it is not proper to discuss it because there is no any real code and patches. It is difficult to understand for me. > > Thanks > > Matthias > > > -- Best Regards, Chanwoo Choi Samsung Electronics