From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-5.4 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI, SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 2FF4EC43331 for ; Fri, 3 Apr 2020 14:40:13 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id C8D862073B for ; Fri, 3 Apr 2020 14:40:12 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=axis.com header.i=@axis.com header.b="OwERzdbT" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2403911AbgDCOkM (ORCPT ); Fri, 3 Apr 2020 10:40:12 -0400 Received: from smtp1.axis.com ([195.60.68.17]:47636 "EHLO smtp1.axis.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728066AbgDCOkM (ORCPT ); Fri, 3 Apr 2020 10:40:12 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=axis.com; l=3375; q=dns/txt; s=axis-central1; t=1585924811; x=1617460811; h=date:from:to:cc:subject:message-id:references: mime-version:content-transfer-encoding:in-reply-to; bh=+zXmvQ71wuVL3YLxRdG+cyS3KAA4sDvpKKdNeB9bCq8=; b=OwERzdbT1UdVAiUUw9vHOJcronkCh0CcT/mYA9pFYH+H2qRRP3eDnKgu 0ub7jffCpCq7UDCV5KXZrgEUWAYqHrd83BBS+ZgzEm4X8o0i6+a6YneD8 3HedzAK79FTj71GzXOB9LTeRuQ31NIeu7StTlUK03l/qZ6DiWb7kBPGCI GoS3YDUshbik7Il+eTUH9vsOHL4RnLNlkwYedO9L7/qoK2h/fP6GHcDde 2RyO3yFcxm0KXP1PzIcc4WvfVa0QAaZIXptzIpqTNDGESgITCzn3IopxH 6mdGdAglVUIudvCoRZfBw50F1MnqOSdshqdb6f2HrYmrH/0DNyNdyeCzc A==; IronPort-SDR: uB+hmrX6WHbLrkXUv7Y6CMpJNYKKlANXcwQzCh+0+yXc/ZJa/1JC4QM038i0kzKea+x2XCuzm2 EiD/xGz3phOKwdwH2/rCbN7AKTLDsIugW95xWBUHNN0swfRVigSFOGvJ8dcG/PqxUIHrs1/PyG PgWo79hFBouSYre9+iust2LC9FB8o7+bedX41vSyz9Jr4J33GoNbGOZbsdpu0VenFiAJzGtfeI FYydH+pq6hnOPE2ptPTldHGt0ePWddz4Z827iUNboNtKo7cqex2QNCM/gI1XDWjZXau6M/Pru1 Jpk= X-IronPort-AV: E=Sophos;i="5.72,340,1580770800"; d="scan'208";a="7290918" Date: Fri, 3 Apr 2020 16:40:09 +0200 From: Vincent Whitchurch To: Daniel Lezcano CC: "rui.zhang@intel.com" , "amit.kucheria@verdurent.com" , "open list:THERMAL" , open list Subject: Re: [PATCH] thermal: core: Send a sysfs notification on trip points Message-ID: <20200403144009.szjoss5ecleisg2f@axis.com> References: <20200402142116.22869-1-daniel.lezcano@linaro.org> MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <20200402142116.22869-1-daniel.lezcano@linaro.org> User-Agent: NeoMutt/20170113 (1.7.2) Sender: linux-pm-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-pm@vger.kernel.org On Thu, Apr 02, 2020 at 04:21:15PM +0200, Daniel Lezcano wrote: > Currently the userspace has no easy way to get notified when a > specific trip point was crossed. There are a couple of approaches: > > - the userspace polls the sysfs temperature with usually an > unacceptable delay between the trip temperature point crossing and > the moment it is detected, or a high polling rate with an > unacceptable number of wakeup events. > > - the thermal zone is set to be managed by an userspace governor in > order to receive the uevent even if the thermal zone needs to be > managed by another governor. > > These changes allow to send a sysfs notification on the > trip_point_*_temp when the temperature is getting higher than the trip > point temperature. By this way, the userspace can be notified > everytime when the trip point is crossed, this is useful for the > thermal Android HAL or for notification to be sent via d-bus. > > That allows the userspace to manage the applications based on specific > alerts on different thermal zones to mitigate the skin temperature, > letting the kernel governors handle the high temperature for hardware > like the CPU, the GPU or the modem. > > The temperature can be oscillating around a trip point and the event > will be sent multiple times. It is up to the userspace to deal with > this situation. The actual temperature value would also be interesting. Is there a way for userspace to obtain it in a race-free manner when it is notified that the trip point has been crossed? > diff --git a/drivers/thermal/thermal_core.c b/drivers/thermal/thermal_core.c > index c06550930979..3cbdd20252ab 100644 > --- a/drivers/thermal/thermal_core.c > +++ b/drivers/thermal/thermal_core.c > @@ -407,6 +407,19 @@ static void handle_critical_trips(struct thermal_zone_device *tz, > } > } > > +static int thermal_trip_crossed(struct thermal_zone_device *tz, int trip) > +{ > + int trip_temp; > + > + tz->ops->get_trip_temp(tz, trip, &trip_temp); > + > + if (tz->last_temperature == THERMAL_TEMP_INVALID) > + return 0; > + > + return ((tz->last_temperature < trip_temp)) && > + (tz->temperature >= trip_temp)); drivers/thermal/thermal_core.c: In function ‘thermal_trip_crossed’: drivers/thermal/thermal_core.c:425:33: error: expected ‘;’ before ‘)’ token (tz->temperature >= trip_temp)); ^ drivers/thermal/thermal_core.c:425:33: error: expected statement before ‘)’ token > +} > + > static void handle_thermal_trip(struct thermal_zone_device *tz, int trip) > { > enum thermal_trip_type type; > @@ -417,6 +430,16 @@ static void handle_thermal_trip(struct thermal_zone_device *tz, int trip) > > tz->ops->get_trip_type(tz, trip, &type); > > + /* > + * This condition will be true everytime the temperature is > + * greater than the trip point and the previous temperature > + * was below. In this case notify the userspace via a sysfs > + * event on the trip point. > + */ > + if (thermal_trip_crossed(tz, trip)) > + sysfs_notify(&tz->device.kobj, NULL, > + tz->trip_temp_attrs[trip].attr.attr.name); Normally sysfs_notify() is used to notify userspace that the value of the sysfs file has changed, but in this case it's being used on a sysfs file whose value never changes. I don't know if there are other drivers that do something similar.