From mboxrd@z Thu Jan 1 00:00:00 1970 From: Akhil P Oommen Subject: Re: [RFC] PM / devfreq: Add support for alerts Date: Fri, 1 Jun 2018 17:13:47 +0530 Message-ID: References: <1527745019-25155-1-git-send-email-akhilpo@codeaurora.org> <20180531061720epcms1p31f5451bcf3150a7dddd33e1e415bb730@epcms1p3> Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <20180531061720epcms1p31f5451bcf3150a7dddd33e1e415bb730@epcms1p3> Content-Language: en-US Sender: linux-kernel-owner@vger.kernel.org To: myungjoo.ham@samsung.com, "linux-pm@vger.kernel.org" , "linux-kernel@vger.kernel.org" , "mka@chromium.org" Cc: "jcrouse@codeaurora.org" , Kyungmin Park , Chanwoo Choi , "linux-arm-msm@vger.kernel.org" List-Id: linux-pm@vger.kernel.org On 5/31/2018 11:47 AM, MyungJoo Ham wrote: >> Currently, DEVFREQ reevaluates the device state periodically and/or >> based on the OPP list changes. Private API has to be exposed to allow >> the device driver to alert/notify the governor to reevaluate when a new >> set of data is available. This makes the governor more coupled to a >> particular device driver. We can improve here by exposing a DEVFREQ API >> to allow the device drivers to send generic alerts to the governor. >> >> Signed-off-by: Akhil P Oommen >> --- >> drivers/devfreq/devfreq.c | 21 +++++++++++++++++++++ >> drivers/devfreq/governor.h | 1 + >> include/linux/devfreq.h | 5 +++++ >> 3 files changed, 27 insertions(+) >> > Hello Akhil, > > It appears that this will have the same effect with > "[PATCH 08/11] PM / devfreq: Make update_devfreq() public" from Matthias Kaehlcke, doesn't it? > > > Cheers, > MyungJoo > Hi MyngJoo, The patch you mentioned is a step in the right direction. But this patch allows: 1. the governor to decide whether to reevaluate or not. I feel it would be a better architecture (better Separation of Concern) if that decision is left to the governor alone. 2. the devices to share multiple types of alerts. A governor may use these alerts for internal bookkeeping/algorithm and decide to reevaluate policy when it is necessary. Since we are opening up a new devfreq API for devices, isn't it better to go for a generic one? Regards, Akhil.