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From: Alexandre Belloni <alexandre.belloni@bootlin.com>
To: Rasmus Villemoes <rasmus.villemoes@prevas.dk>
Cc: linux-rtc@vger.kernel.org,
	"Per Nørgaard Christensen" <per.christensen@prevas.dk>,
	linux-kernel@vger.kernel.org
Subject: Re: [PATCH 5/5] rtc: pcf2127: report battery switch over
Date: Wed, 6 May 2020 00:09:11 +0200	[thread overview]
Message-ID: <20200505220911.GW34497@piout.net> (raw)
In-Reply-To: <e4910679-4453-f753-2c3e-4c93fd755b39@prevas.dk>

On 05/05/2020 23:30:18+0200, Rasmus Villemoes wrote:
> On 05/05/2020 22.13, Alexandre Belloni wrote:
> > Add support for the RTC_VL_BACKUP_SWITCH flag to report battery switch over
> > events.
> > 
> > Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>
> > ---
> >  drivers/rtc/rtc-pcf2127.c | 16 ++++++++++++----
> >  1 file changed, 12 insertions(+), 4 deletions(-)
> > 
> > diff --git a/drivers/rtc/rtc-pcf2127.c b/drivers/rtc/rtc-pcf2127.c
> > index 039078029bd4..967de68e1b03 100644
> > --- a/drivers/rtc/rtc-pcf2127.c
> > +++ b/drivers/rtc/rtc-pcf2127.c
> > @@ -188,18 +188,27 @@ static int pcf2127_rtc_ioctl(struct device *dev,
> >  				unsigned int cmd, unsigned long arg)
> >  {
> >  	struct pcf2127 *pcf2127 = dev_get_drvdata(dev);
> > -	int touser;
> > +	int val, touser = 0;
> >  	int ret;
> >  
> >  	switch (cmd) {
> >  	case RTC_VL_READ:
> > -		ret = regmap_read(pcf2127->regmap, PCF2127_REG_CTRL3, &touser);
> > +		ret = regmap_read(pcf2127->regmap, PCF2127_REG_CTRL3, &val);
> >  		if (ret)
> >  			return ret;
> >  
> > -		touser = touser & PCF2127_BIT_CTRL3_BLF ? RTC_VL_BACKUP_LOW : 0;
> > +		if (val & PCF2127_BIT_CTRL3_BLF)
> > +			touser = RTC_VL_BACKUP_LOW;
> > +
> > +		if (val & PCF2127_BIT_CTRL3_BF)
> > +			touser |= RTC_VL_BACKUP_SWITCH;
> 
> I think it's a bit easier to read if you use |= in both cases.
> 
> Re patch 3, one saves a little .text by eliding the ioctl function when,
> as you say, it cannot be called anyway. No strong opinion either way, I
> don't think anybody actually builds without CONFIG_RTC_INTF_DEV, but
> those that do are probably the ones that care about having a tiny vmlinux.
> 

Honestly, I don't think it is worth doing that. On armv7, this only
removes 248 bytes. Also, compiling without CONFIG_RTC_INTF_DEV simply
makes the RTC unusable. There are no tools actually using the sysfs
interface instead of the char device interface. I prefer keeping
CONFIG_RTC_INTF_DEV private to the core.

-- 
Alexandre Belloni, Bootlin
Embedded Linux and Kernel engineering
https://bootlin.com

      reply	other threads:[~2020-05-05 22:09 UTC|newest]

Thread overview: 7+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-05-05 20:13 [PATCH 1/5] rtc: add new VL flag for backup switchover Alexandre Belloni
2020-05-05 20:13 ` [PATCH 2/5] rtc: pcf2127: let the core handle rtc range Alexandre Belloni
2020-05-05 20:13 ` [PATCH 3/5] rtc: pcf2127: remove unnecessary #ifdef Alexandre Belloni
2020-05-05 20:13 ` [PATCH 4/5] rtc: pcf2127: set regmap max_register Alexandre Belloni
2020-05-05 20:13 ` [PATCH 5/5] rtc: pcf2127: report battery switch over Alexandre Belloni
2020-05-05 21:30   ` Rasmus Villemoes
2020-05-05 22:09     ` Alexandre Belloni [this message]

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