linux-kernel - Re: [PATCH resubmit] rtc: interface: Add RTC offset to alarm after fix-up

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Date: Wed, 19 Jun 2024 15:26:38 +0200
From: Alexandre Belloni <alexandre.belloni@...tlin.com>
To: Csókás, Bence <csokas.bence@...lan.hu>
Cc: linux-rtc@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH resubmit] rtc: interface: Add RTC offset to alarm after
 fix-up

On 19/06/2024 15:01:16+0200, Csókás, Bence wrote:
> `rtc_add_offset()` is called by `__rtc_read_time()`
> and `__rtc_read_alarm()` to add the RTC's offset to
> the raw read-outs from the device drivers. However,
> in the latter case, a fix-up algorithm is run if
> the RTC device does not report a full `struct rtc_time`
> alarm value. In that case, the offset was forgot to be
> added.
> 
> Fixes: fd6792bb022e ("rtc: fix alarm read and set offset")
> 
> Signed-off-by: Csókás, Bence <csokas.bence@...lan.hu>
> ---
>  drivers/rtc/interface.c | 5 +++--
>  1 file changed, 3 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/rtc/interface.c b/drivers/rtc/interface.c
> index 1b63111cdda2..db8dffffed91 100644
> --- a/drivers/rtc/interface.c
> +++ b/drivers/rtc/interface.c
> @@ -273,12 +273,11 @@ int __rtc_read_alarm(struct rtc_device *rtc, struct rtc_wkalrm *alarm)
>  		if (err)
>  			return err;
>  
>  		/* full-function RTCs won't have such missing fields */
>  		if (rtc_valid_tm(&alarm->time) == 0) {
> -			rtc_add_offset(rtc, &alarm->time);
> -			return 0;
> +			goto done;
>  		}
>  
>  		/* get the "after" timestamp, to detect wrapped fields */
>  		err = rtc_read_time(rtc, &now);
>  		if (err < 0)
> @@ -378,10 +377,12 @@ int __rtc_read_alarm(struct rtc_device *rtc, struct rtc_wkalrm *alarm)
>  done:
>  	if (err && alarm->enabled)
>  		dev_warn(&rtc->dev, "invalid alarm value: %ptR\n",
>  			 &alarm->time);
>  
> +	rtc_add_offset(rtc, &alarm->time);
> +

This must not be done when the tm is invalid.

>  	return err;
>  }
>  
>  int rtc_read_alarm(struct rtc_device *rtc, struct rtc_wkalrm *alarm)
>  {
> -- 
> 2.34.1
> 
> 

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