[3.8.y.z extended stable] Patch "ARM: fix footbridge clockevent device" has been added to staging queue

[Kamal Mostafa]

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

    ARM: fix footbridge clockevent device

to the linux-3.8.y-queue branch of the 3.8.y.z extended stable tree 
which can be found at:

 http://kernel.ubuntu.com/git?p=ubuntu/linux.git;a=shortlog;h=refs/heads/linux-3.8.y-queue

This patch is scheduled to be released in version 3.8.13.16.

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

For more information about the 3.8.y.z tree, see
https://wiki.ubuntu.com/Kernel/Dev/ExtendedStable

Thanks.
-Kamal

------

>From 68e02a709f60b3b99f4a5546e0a56f06ba13b098 Mon Sep 17 00:00:00 2001
From: Russell King <rmk+kernel at arm.linux.org.uk>
Date: Sun, 29 Dec 2013 12:39:50 +0000
Subject: ARM: fix footbridge clockevent device

commit 4ff859fe1dc0da0f87bbdfff78f527898878fa4a upstream.

The clockevents code was being told that the footbridge clock event
device ticks at 16x the rate which it actually does.  This leads to
timekeeping problems since it allows the clocksource to wrap before
the kernel notices.  Fix this by using the correct clock.

Fixes: 4e8d76373c9fd ("ARM: footbridge: convert to clockevents/clocksource")
Signed-off-by: Russell King <rmk+kernel at arm.linux.org.uk>
[ kamal: backport to 3.8: also applied prereq dc21285-timer.c change from
  838a2ae "ARM: use clockevents_config_and_register() where possible" ]
Signed-off-by: Kamal Mostafa <kamal at canonical.com>
---
 arch/arm/mach-footbridge/dc21285-timer.c | 9 +++------
 1 file changed, 3 insertions(+), 6 deletions(-)

diff --git a/arch/arm/mach-footbridge/dc21285-timer.c b/arch/arm/mach-footbridge/dc21285-timer.c
index 3b54196..edb0ef3 100644
--- a/arch/arm/mach-footbridge/dc21285-timer.c
+++ b/arch/arm/mach-footbridge/dc21285-timer.c
@@ -96,17 +96,14 @@ static struct irqaction footbridge_timer_irq = {
 static void __init footbridge_timer_init(void)
 {
 	struct clock_event_device *ce = &ckevt_dc21285;
+	unsigned rate = DIV_ROUND_CLOSEST(mem_fclk_21285, 16);

-	clocksource_register_hz(&cksrc_dc21285, (mem_fclk_21285 + 8) / 16);
+	clocksource_register_hz(&cksrc_dc21285, rate);

 	setup_irq(ce->irq, &footbridge_timer_irq);

-	clockevents_calc_mult_shift(ce, mem_fclk_21285, 5);
-	ce->max_delta_ns = clockevent_delta2ns(0xffffff, ce);
-	ce->min_delta_ns = clockevent_delta2ns(0x000004, ce);
 	ce->cpumask = cpumask_of(smp_processor_id());
-
-	clockevents_register_device(ce);
+	clockevents_config_and_register(ce, rate, 0x4, 0xffffff);
 }

 struct sys_timer footbridge_timer = {
--
1.8.3.2