Patch "rtc: s3c: Add s3c_rtc_{enable/disable}_clk in s3c_rtc_setfreq()" has been added to the 4.4-stable tree

[<gregkh@linuxfoundation.org>]

This is a note to let you know that I've just added the patch titled

    rtc: s3c: Add s3c_rtc_{enable/disable}_clk in s3c_rtc_setfreq()

to the 4.4-stable tree which can be found at:
    http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
     rtc-s3c-add-s3c_rtc_-enable-disable-_clk-in-s3c_rtc_setfreq.patch
and it can be found in the queue-4.4 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@vger.kernel.org> know about it.


>From 70c96dfac0e231424e17743bd52f6cd2ff1f2439 Mon Sep 17 00:00:00 2001
From: Alim Akhtar <alim.akhtar@samsung.com>
Date: Tue, 5 Jul 2016 15:28:53 +0530
Subject: rtc: s3c: Add s3c_rtc_{enable/disable}_clk in s3c_rtc_setfreq()

From: Alim Akhtar <alim.akhtar@samsung.com>

commit 70c96dfac0e231424e17743bd52f6cd2ff1f2439 upstream.

As per code flow s3c_rtc_setfreq() will get called with rtc clock disabled
and in set_freq we perform h/w registers read/write, which results in a
kernel crash on exynos7 platform while probing rtc driver.
Below is code flow:
s3c_rtc_probe()
    clk_prepare_enable(info->rtc_clk) // rtc clock enabled
    s3c_rtc_gettime() // will enable clk if not done, and disable it upon exit
    s3c_rtc_setfreq() //then this will be called with clk disabled

This patch take cares of such issue by adding s3c_rtc_{enable/disable}_clk in
s3c_rtc_setfreq().

Fixes: 24e1455493da ("drivers/rtc/rtc-s3c.c: delete duplicate clock control")
Signed-off-by: Alim Akhtar <alim.akhtar@samsung.com>
Reviewed-by: Krzysztof Kozlowski <k.kozlowski@samsung.com>
Reviewed-by: Pankaj Dubey <pankaj.dubey@samsung.com>
Tested-by: Pankaj Dubey <pankaj.dubey@samsung.com>
Signed-off-by: Alexandre Belloni <alexandre.belloni@free-electrons.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
 drivers/rtc/rtc-s3c.c |    2 ++
 1 file changed, 2 insertions(+)

--- a/drivers/rtc/rtc-s3c.c
+++ b/drivers/rtc/rtc-s3c.c
@@ -149,12 +149,14 @@ static int s3c_rtc_setfreq(struct s3c_rt
 	if (!is_power_of_2(freq))
 		return -EINVAL;
 
+	s3c_rtc_enable_clk(info);
 	spin_lock_irq(&info->pie_lock);
 
 	if (info->data->set_freq)
 		info->data->set_freq(info, freq);
 
 	spin_unlock_irq(&info->pie_lock);
+	s3c_rtc_disable_clk(info);
 
 	return 0;
 }


Patches currently in stable-queue which might be from alim.akhtar@samsung.com are

queue-4.4/rtc-s3c-add-s3c_rtc_-enable-disable-_clk-in-s3c_rtc_setfreq.patch