FAILED: patch "[PATCH] rtc: rzn1: Handle unset alarm weekday in rzn1_rtc_read_alarm" failed to apply to 6.1-stable tree

The patch below does not apply to the 6.1-stable tree.
If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to <[email protected]>.

To reproduce the conflict and resubmit, you may use the following commands:

git fetch https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/ linux-6.1.y
git checkout FETCH_HEAD
git cherry-pick -x 457b5dbce31209e65e1184716ed3af59cb1c0372
# <resolve conflicts, build, test, etc.>
git commit -s
git send-email --to '<[email protected]>' --in-reply-to '2026090900-washout-open-1097@gregkh' --subject-prefix 'PATCH 6.1.y' 'HEAD^..'

Possible dependencies:

thanks,

greg k-h

------------------ original commit in Linus's tree ------------------

From 457b5dbce31209e65e1184716ed3af59cb1c0372 Mon Sep 17 00:00:00 2001
From: Lad Prabhakar <[email protected]>
Date: Fri, 21 Aug 2026 22:10:19 +0100
Subject: [PATCH] rtc: rzn1: Handle unset alarm weekday in rzn1_rtc_read_alarm

RZN1_RTC_ALW is a weekday bitmask where bit N represents weekday N. When no alarm has been configured, the register has its power-on-reset value of zero.

rzn1_rtc_read_alarm() uses fls() to convert the weekday bitmask into a weekday number. When RZN1_RTC_ALW is zero, fls(0) returns zero and fls(wday) - 1 evaluates to -1. This invalid weekday is then used to calculate the alarm date and can either leave tm_wday set to -1 or produce a fabricated alarm date.

Treat a zero RZN1_RTC_ALW value as an unset alarm weekday and return without calculating the alarm date. Move reading RZN1_RTC_CTL1 before this check so that alrm->enabled is updated for both configured and unconfigured alarms.

index 56284a4320ae..d4cba0d415b6 100644
@@ -235,13 +235,24 @@ static int rzn1_rtc_read_alarm(struct device *dev, struct rtc_wkalrm *alrm)
 	if (ret)
 		return ret;
 
+	ctl1 = readl(rtc->base + RZN1_RTC_CTL1);
+	alrm->enabled = !!(ctl1 & (RZN1_RTC_CTL1_ALME | RZN1_RTC_CTL1_1SE));
+
 	min = readl(rtc->base + RZN1_RTC_ALM);
 	hour = readl(rtc->base + RZN1_RTC_ALH);
-	wday = readl(rtc->base + RZN1_RTC_ALW);
 
 	tm->tm_sec = 0;
 	tm->tm_min = bcd2bin(min);
 	tm->tm_hour = bcd2bin(hour);
+
+	/*
+	 * If wday is zero, no bit is set in RZN1_RTC_ALW. This is the
+	 * register's power-on reset value.
+	 */
+	wday = readl(rtc->base + RZN1_RTC_ALW);
+	if (!wday)
+		return 0;
+
 	delta_days = ((fls(wday) - 1) - tm->tm_wday + 7) % 7;
 	tm->tm_wday = fls(wday) - 1;
 

@@ -250,9 +261,6 @@ static int rzn1_rtc_read_alarm(struct device *dev, struct rtc_wkalrm *alrm)
 		rtc_time64_to_tm(alarm, tm);
 	}
 
-	ctl1 = readl(rtc->base + RZN1_RTC_CTL1);
-	alrm->enabled = !!(ctl1 & (RZN1_RTC_CTL1_ALME | RZN1_RTC_CTL1_1SE));
-
 	return 0;
 }
 

From: Lad Prabhakar <[email protected]>

[ Upstream commit 457b5dbce31209e65e1184716ed3af59cb1c0372 ]

RZN1_RTC_ALW is a weekday bitmask where bit N represents weekday N. When no alarm has been configured, the register has its power-on-reset value of zero.

rzn1_rtc_read_alarm() uses fls() to convert the weekday bitmask into a weekday number. When RZN1_RTC_ALW is zero, fls(0) returns zero and fls(wday) - 1 evaluates to -1. This invalid weekday is then used to calculate the alarm date and can either leave tm_wday set to -1 or produce a fabricated alarm date.

Treat a zero RZN1_RTC_ALW value as an unset alarm weekday and return without calculating the alarm date. Move reading RZN1_RTC_CTL1 before this check so that alrm->enabled is updated for both configured and unconfigured alarms.

---
 drivers/rtc/rtc-rzn1.c | 16 ++++++++++++----
 1 file changed, 12 insertions(+), 4 deletions(-)

index ff094b3ce9e3c..800a0644b877d 100644
@@ -193,13 +193,24 @@ static int rzn1_rtc_read_alarm(struct device *dev, struct rtc_wkalrm *alrm)
 	if (ret)
 		return ret;
 
+	ctl1 = readl(rtc->base + RZN1_RTC_CTL1);
+	alrm->enabled = !!(ctl1 & RZN1_RTC_CTL1_ALME);
+
 	min = readl(rtc->base + RZN1_RTC_ALM);
 	hour = readl(rtc->base + RZN1_RTC_ALH);
-	wday = readl(rtc->base + RZN1_RTC_ALW);
 
 	tm->tm_sec = 0;
 	tm->tm_min = bcd2bin(min);
 	tm->tm_hour = bcd2bin(hour);
+
+	/*
+	 * If wday is zero, no bit is set in RZN1_RTC_ALW. This is the
+	 * register's power-on reset value.
+	 */
+	wday = readl(rtc->base + RZN1_RTC_ALW);
+	if (!wday)
+		return 0;
+
 	delta_days = ((fls(wday) - 1) - tm->tm_wday + 7) % 7;
 	tm->tm_wday = fls(wday) - 1;
 

@@ -208,9 +219,6 @@ static int rzn1_rtc_read_alarm(struct device *dev, struct rtc_wkalrm *alrm)
 		rtc_time64_to_tm(alarm, tm);
 	}
 
-	ctl1 = readl(rtc->base + RZN1_RTC_CTL1);
-	alrm->enabled = !!(ctl1 & RZN1_RTC_CTL1_ALME);
-
 	return 0;
 }
 

2.53.0