Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754648AbbDHQyV (ORCPT ); Wed, 8 Apr 2015 12:54:21 -0400 Received: from bh-25.webhostbox.net ([208.91.199.152]:37824 "EHLO bh-25.webhostbox.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754348AbbDHQyR (ORCPT ); Wed, 8 Apr 2015 12:54:17 -0400 Date: Wed, 8 Apr 2015 09:53:51 -0700 From: Guenter Roeck To: Anand Moon Cc: Lukasz Majewski , Eduardo Valentin , Sjoerd Simons , Russell King , Kukjin Kim , devicetree@vger.kernel.org, "linux-samsung-soc@vger.kernel.org" , linux-pwm@vger.kernel.org, linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org Subject: Re: [PATCH 6/6] hwmon: pwm-fan: Update the duty cycle inorder to control the pwm-fan Message-ID: <20150408165351.GA22846@roeck-us.net> References: <1427387955-5129-1-git-send-email-linux.amoon@gmail.com> <1427387955-5129-7-git-send-email-linux.amoon@gmail.com> <20150408104415.07e1c821@amdc2363> <20150408153214.GA15942@roeck-us.net> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.5.23 (2014-03-12) X-Authenticated_sender: guenter@roeck-us.net X-OutGoing-Spam-Status: No, score=-1.0 X-CTCH-PVer: 0000001 X-CTCH-Spam: Unknown X-CTCH-VOD: Unknown X-CTCH-Flags: 0 X-CTCH-RefID: str=0001.0A020204.55255D39.00F9,ss=1,re=0.001,recu=0.000,reip=0.000,cl=1,cld=1,fgs=0 X-CTCH-Score: 0.001 X-CTCH-ScoreCust: 0.000 X-CTCH-Rules: C_4847, X-CTCH-SenderID: linux@roeck-us.net X-CTCH-SenderID-Flags: 0 X-CTCH-SenderID-TotalMessages: 10 X-CTCH-SenderID-TotalSpam: 0 X-CTCH-SenderID-TotalSuspected: 0 X-CTCH-SenderID-TotalConfirmed: 0 X-CTCH-SenderID-TotalBulk: 0 X-CTCH-SenderID-TotalVirus: 0 X-CTCH-SenderID-TotalRecipients: 0 X-AntiAbuse: This header was added to track abuse, please include it with any abuse report X-AntiAbuse: Primary Hostname - bh-25.webhostbox.net X-AntiAbuse: Original Domain - vger.kernel.org X-AntiAbuse: Originator/Caller UID/GID - [47 12] / [47 12] X-AntiAbuse: Sender Address Domain - roeck-us.net X-Get-Message-Sender-Via: bh-25.webhostbox.net: mailgid no entry from get_relayhosts_entry X-Source: X-Source-Args: X-Source-Dir: Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 3730 Lines: 110 On Wed, Apr 08, 2015 at 09:32:05PM +0530, Anand Moon wrote: > Hi Guenter, > > Initially the board bootup the cooling level state is 0. > So update the duty cycle and this power off the fan. > As their is no state change the fan will not spin. > > Once the temperature sensor is reached to alert temperature it changes state. > With the state change the fan cools the CPU and then stop's > > I have observed this state change with tmon utility in linux/tools/thermal/tmon/ > Sorry, I am missing something. I still don't see what problem you are fixing with this patch. What behavior is wrong with the current code, and how does your patch fix it ? Guenter > -Anand Moon > > On 8 April 2015 at 21:02, Guenter Roeck wrote: > > On Wed, Apr 08, 2015 at 10:44:15AM +0200, Lukasz Majewski wrote: > >> Hi Anand, > >> > >> > Below changes depend on following patch. > >> > https://patchwork.kernel.org/patch/5944061/ > >> > > >> > Update the pwm_config with duty then update the pwm_disable > >> > to poweroff the cpu fan. > >> > > > > > Unfortunately, the patch does not include an explanation why it is needed. > > > > The original code presumably did not update the duty cycle because > > pwm was about to be disabled anyway. That kind of made sense to me. > > Updating the duty cycle to 0 just to disable the pwm channel right > > afterwards does not immediately make sense. > > > > Given that, I would expect to see a rationale here. Why is this patch needed ? > > Does it fix a bug ? If yes, pelase describe the bug. If not, what is the > > purpose of this patch ? > > > > Maybe that is all explained in patch 0/6, which I was not copied on. Even > > if so, the reationale will be needed in the changelog to explain to future > > developers why this change was made. > > > > Thanks, > > Guenter > > > >> > Tested on OdroidXU3 board. > >> > > >> > Signed-off-by: Anand Moon > >> > --- > >> > drivers/hwmon/pwm-fan.c | 10 ++++------ > >> > 1 file changed, 4 insertions(+), 6 deletions(-) > >> > > >> > diff --git a/drivers/hwmon/pwm-fan.c b/drivers/hwmon/pwm-fan.c > >> > index 7c83dc4..f25c841 100644 > >> > --- a/drivers/hwmon/pwm-fan.c > >> > +++ b/drivers/hwmon/pwm-fan.c > >> > @@ -44,26 +44,24 @@ static int __set_pwm(struct pwm_fan_ctx *ctx, > >> > unsigned long pwm) int ret = 0; > >> > > >> > mutex_lock(&ctx->lock); > >> > + > > > > [ please refrain from unnecessary whitespace changes ] > > > >> > if (ctx->pwm_value == pwm) > >> > goto exit_set_pwm_err; > >> > > >> > - if (pwm == 0) { > >> > - pwm_disable(ctx->pwm); > >> > - goto exit_set_pwm; > >> > - } > >> > - > >> > duty = DIV_ROUND_UP(pwm * (ctx->pwm->period - 1), MAX_PWM); > >> > ret = pwm_config(ctx->pwm, duty, ctx->pwm->period); > >> > if (ret) > >> > goto exit_set_pwm_err; > >> > > >> > + if (pwm == 0) > >> > + pwm_disable(ctx->pwm); > >> > + > >> > if (ctx->pwm_value == 0) { > >> > ret = pwm_enable(ctx->pwm); > >> > if (ret) > >> > goto exit_set_pwm_err; > >> > } > >> > > >> > -exit_set_pwm: > >> > ctx->pwm_value = pwm; > >> > exit_set_pwm_err: > >> > mutex_unlock(&ctx->lock); > >> > >> Reviewed-by: Lukasz Majewski > >> > >> BTW: I've added Guenter to CC. > >> > >> -- > >> Best regards, > >> > >> Lukasz Majewski > >> > >> Samsung R&D Institute Poland (SRPOL) | Linux Platform Group -- 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/