linux-kernel - Re: [PATCH 11/29] rtc: pcf2127: set RTC_FEATURE_ALARM_RES

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Message-Id: <20220310161253.c2e90fdf05619aada86e217d@hugovil.com>
Date:   Thu, 10 Mar 2022 16:12:53 -0500
From:   Hugo Villeneuve <hugo@...ovil.com>
To:     Alexandre Belloni <alexandre.belloni@...tlin.com>
Cc:     Alessandro Zummo <a.zummo@...ertech.it>, linux-rtc@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH 11/29] rtc: pcf2127: set RTC_FEATURE_ALARM_RES_2S

On Thu, 10 Mar 2022 21:58:49 +0100
Alexandre Belloni <alexandre.belloni@...tlin.com> wrote:

> On 10/03/2022 11:09:18-0500, Hugo Villeneuve wrote:
> > On Wed,  9 Mar 2022 17:22:42 +0100
> > Alexandre Belloni <alexandre.belloni@...tlin.com> wrote:
> > 
> > > The PCF2127 doesn't support UIE because setting an alarm to fire every
> > > second confuses the chip and the fastest we can go is an alarm every 2
> > > seconds.
> > 
> > Hi Alexandre,
> > can you describe what "confuses the chip" means?
> > 
> > In my experimental PCF2131 driver, I activated UIE and it seems to be working fine at 1s intervals, but since it is similar to PCF2127, maybe there is still a problem and I just didn't see it.
> > 
> 
> Did you remove uie_unsupported? Else, you may have been using uie
> emulation. In my tests last year, the pcf2127 was failing to reassert
> the interrupt if an alarm was set every second. The same happens on
> other NXP based RTCs (i.e. including microcrystal ones).

Hi,
yes, I did remove uie_unsupported, and I specifically disabled UIE emulation in my kernel configuration.

> I'm going to test again soon (and also reply to your series).

Ok, great.

> > Hugo.
> > 
> > 
> > > Signed-off-by: Alexandre Belloni <alexandre.belloni@...tlin.com>
> > > ---
> > >  drivers/rtc/rtc-pcf2127.c | 1 +
> > >  1 file changed, 1 insertion(+)
> > > 
> > > diff --git a/drivers/rtc/rtc-pcf2127.c b/drivers/rtc/rtc-pcf2127.c
> > > index f8469b134411..63b275b014bd 100644
> > > --- a/drivers/rtc/rtc-pcf2127.c
> > > +++ b/drivers/rtc/rtc-pcf2127.c
> > > @@ -656,6 +656,7 @@ static int pcf2127_probe(struct device *dev, struct regmap *regmap,
> > >  	pcf2127->rtc->range_min = RTC_TIMESTAMP_BEGIN_2000;
> > >  	pcf2127->rtc->range_max = RTC_TIMESTAMP_END_2099;
> > >  	pcf2127->rtc->set_start_time = true; /* Sets actual start to 1970 */
> > > +	set_bit(RTC_FEATURE_ALARM_RES_2S, pcf2127->rtc->features);
> > >  	clear_bit(RTC_FEATURE_UPDATE_INTERRUPT, pcf2127->rtc->features);
> > >  	clear_bit(RTC_FEATURE_ALARM, pcf2127->rtc->features);
> > >  
> > > -- 
> > > 2.35.1
> > > 
> > 
> > 
> > -- 
> > Hugo Villeneuve <hugo@...ovil.com>
> 
> -- 
> Alexandre Belloni, co-owner and COO, Bootlin
> Embedded Linux and Kernel engineering
> https://bootlin.com
> 


-- 
Hugo Villeneuve <hugo@...ovil.com>