[ 3.5.y.z extended stable ] Patch "drivers/rtc/rtc-pl031.c: restore ST variant functionality" has been added to staging queue

Herton Ronaldo Krzesinski herton.krzesinski at canonical.com
Fri Feb 15 17:03:06 UTC 2013

This is a note to let you know that I have just added a patch titled

    drivers/rtc/rtc-pl031.c: restore ST variant functionality

to the linux-3.5.y-queue branch of the 3.5.y.z extended stable tree 
which can be found at:


If you, or anyone else, feels it should not be added to this tree, please 
reply to this email.

For more information about the 3.5.y.z tree, see



>From e9df506c393a0b37ea4d5050ff20e045678f70d5 Mon Sep 17 00:00:00 2001
From: Linus Walleij <linus.walleij at linaro.org>
Date: Tue, 12 Feb 2013 13:46:19 -0800
Subject: [PATCH] drivers/rtc/rtc-pl031.c: restore ST variant functionality

commit 3399cfb5df9594495b876d1843a7165f77366b2b upstream.

Commit e7e034e18a0a ("drivers/rtc/rtc-pl031.c: fix the missing operation
on enable") accidentally broke the ST variants of PL031.

The bit that is being poked as "clockwatch" enable bit for the ST
variants does the work of bit 0 on this variant.  Bit 0 is used for a
clock divider on the ST variants, and setting it to 1 will affect
timekeeping in a very bad way.

Signed-off-by: Linus Walleij <linus.walleij at linaro.org>
Acked-by: Haojian Zhuang <haojian.zhuang at gmail.com>
Cc: Mian Yousaf KAUKAB <mian.yousaf.kaukab at stericsson.com>
Cc: Srinidhi Kasagar <srinidhi.kasagar at stericsson.com>
Cc: Alessandro Zummo <a.zummo at towertech.it>
Signed-off-by: Andrew Morton <akpm at linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds at linux-foundation.org>
[ herton: adjust context ]
Signed-off-by: Herton Ronaldo Krzesinski <herton.krzesinski at canonical.com>
 drivers/rtc/rtc-pl031.c |    4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/drivers/rtc/rtc-pl031.c b/drivers/rtc/rtc-pl031.c
index c42054b..b232996 100644
--- a/drivers/rtc/rtc-pl031.c
+++ b/drivers/rtc/rtc-pl031.c
@@ -336,7 +336,9 @@ static int pl031_probe(struct amba_device *adev, const struct amba_id *id)
 	/* Enable the clockwatch on ST Variants */
 	if (ldata->hw_designer == AMBA_VENDOR_ST)
 		data |= RTC_CR_CWEN;
-	writel(data | RTC_CR_EN, ldata->base + RTC_CR);
+	else
+		data |= RTC_CR_EN;
+	writel(data, ldata->base + RTC_CR);

 	 * On ST PL031 variants, the RTC reset value does not provide correct

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