Hi Guenter/Lukasz, Earlier I send v2 version of the patch spiking this one. Markus Riechl came back to me with below mail. So This patch confirms fixes the bug. I will send v3 version of the patch. Earlier I was in delima about the bug. -Anand Moon ------------------------------------------- Hi Anand, I tested your patch. After booting the fan is spinning despite only 44°C. /sys/class/thermal/cooling_device0/curstate is 0. /sys/class/hwmon/hwmon4/pwm1 is 0 when I echo 1 > cur_state and then echo 0 > cur_state again, the fan switches to off and behaves as expected. It looks like there is a bug in initializing the pwm output immediately after booting. Best Regards, -- Markus Reichl On 8 April 2015 at 23:19, Anand Moon <linux.amoon@xxxxxxxxx> wrote: > Hi Guenter, > > Sorry my blunder mistake. Sorry for the noise. > > I just tested with spiking this patch and my observation and testing > were wrong we can skip this patch. > > I will send an v2 patch series removing the patch 5 and patch 6. > > With correct dts changes. > > Thanks for pointing my mistake. > > -Anand Moon > > On 8 April 2015 at 22:23, Guenter Roeck <linux@xxxxxxxxxxxx> wrote: >> 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 <linux@xxxxxxxxxxxx> 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 <linux.amoon@xxxxxxxxx> >>> >> > --- >>> >> > 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 <l.majewski@xxxxxxxxxxx> >>> >> >>> >> 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 devicetree" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
