Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1761776AbaGRQYf (ORCPT ); Fri, 18 Jul 2014 12:24:35 -0400 Received: from smtprelay04.ispgateway.de ([80.67.31.38]:51880 "EHLO smtprelay04.ispgateway.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755741AbaGRQYe (ORCPT ); Fri, 18 Jul 2014 12:24:34 -0400 References: <1398561815-22033-1-git-send-email-peter@piie.net> <1399139966-10625-1-git-send-email-peter@piie.net> <1399139966-10625-4-git-send-email-peter@piie.net> <20140717095855.GC23869@pd.tnic> Message-ID: X-Mailer: http://www.courier-mta.org/cone/ From: Peter Feuerer To: Borislav Petkov Cc: LKML , Andrew Morton , Zhang Rui , Andreas Mohr , Borislav Petkov , Javi Merino Subject: Re: [PATCH v3 3/6] thermal: Added Bang-bang thermal governor Date: Fri, 18 Jul 2014 18:24:29 +0200 Mime-Version: 1.0 Content-Type: text/plain; format=flowed; charset="US-ASCII" Content-Disposition: inline Content-Transfer-Encoding: 7bit X-Df-Sender: NDA0MDk0 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Borislav Petkov writes: > On Sat, May 03, 2014 at 07:59:23PM +0200, Peter Feuerer wrote: >> The bang-bang thermal governor uses a hysteresis to switch abruptly on >> or off a cooling device. It is intended to control fans, which can >> not be throttled but just switched on or off. >> Bang-bang cannot be set as default governor as it is intended for >> special devices only. For those special devices the driver needs to >> explicitely request it. >> >> Cc: Andrew Morton >> Cc: Zhang Rui >> Cc: Andreas Mohr >> Cc: Borislav Petkov >> Cc: Javi Merino >> Signed-off-by: Peter Feuerer > > ... > >> +static void thermal_zone_trip_update(struct thermal_zone_device *tz, int trip) >> +{ >> + long trip_temp; >> + unsigned long trip_hyst; >> + struct thermal_instance *instance; >> + >> + tz->ops->get_trip_temp(tz, trip, &trip_temp); >> + tz->ops->get_trip_hyst(tz, trip, &trip_hyst); >> + >> + dev_dbg(&tz->device, "Trip%d[temp=%ld]:temp=%d:hyst=%ld\n", >> + trip, trip_temp, tz->temperature, >> + trip_hyst); >> + >> + mutex_lock(&tz->lock); >> + >> + list_for_each_entry(instance, &tz->thermal_instances, tz_node) { >> + if (instance->trip != trip) >> + continue; >> + >> + /* in case fan is in initial state, switch the fan off */ >> + if (instance->target == THERMAL_NO_TARGET) >> + instance->target = 0; >> + >> + /* in case fan is neither on nor off set the fan to active */ >> + if (instance->target != 0 && instance->target != 1) { > > ->target is unsigned long so > > if (instance->target > 1) Right, but I wanted to clearly point out the two possible states. > (and btw, a whole unsigned long for a cooling state... 2^64-1 cooling > states, nice). Hehe, true, maybe u8 makes more sense, so the compiler can take the action to align it accordingly to prevent bit shifting. > >> + pr_warn("Thermal instance %s controlled by bang-bang has unexpected state: %ld\n", >> + instance->name, instance->target); >> + instance->target = 1; >> + } > > Can that even happen? It should not, but if so, we have a warning and I have the feeling we should keep it there. -- --peter; -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/