linux-kernel - Re: [PATCH 5/5] rtc: pcf2127: report battery switch over

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Date:   Tue, 5 May 2020 23:30:18 +0200
From:   Rasmus Villemoes <rasmus.villemoes@...vas.dk>
To:     Alexandre Belloni <alexandre.belloni@...tlin.com>,
        linux-rtc@...r.kernel.org
Cc:     Per Nørgaard Christensen 
        <per.christensen@...vas.dk>, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 5/5] rtc: pcf2127: report battery switch over

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@...tlin.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.

Other than that, the series looks good to me.

Thanks,
Rasmus