lkml.org 
[lkml]   [2014]   [Mar]   [6]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
Patch in this message
/
Date
From
Subject[tip:timers/urgent] clocksource: vf_pit_timer: use complement for sched_clock reading
Commit-ID:  224aa3ed45c8735ae02bb2ecca002409fa6aa772
Gitweb: http://git.kernel.org/tip/224aa3ed45c8735ae02bb2ecca002409fa6aa772
Author: Stefan Agner <stefan@agner.ch>
AuthorDate: Wed, 5 Mar 2014 23:11:08 +0100
Committer: Thomas Gleixner <tglx@linutronix.de>
CommitDate: Thu, 6 Mar 2014 11:34:14 +0100

clocksource: vf_pit_timer: use complement for sched_clock reading

Vybrids PIT register is monitonic decreasing. However, sched_clock
reading needs to be monitonic increasing. Use bitwise not to get
the complement of the clock register. This fixes the clock going
backward. Also, the clock now starts at 0 since we load the
register with the maximum value at start.

Signed-off-by: Stefan Agner <stefan@agner.ch>
Acked-by: Shawn Guo <shawn.guo@linaro.org>
Cc: daniel.lezcano@linaro.org
Cc: linux-arm-kernel@lists.infradead.org
Cc: linux@arm.linux.org.uk
Link: http://lkml.kernel.org/r/d25af915993aec1b486be653eb86f748ddef54fe.1394057313.git.stefan@agner.ch
Cc: stable@vger.kernel.org
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
---
drivers/clocksource/vf_pit_timer.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/clocksource/vf_pit_timer.c b/drivers/clocksource/vf_pit_timer.c
index 02821b0..a918bc4 100644
--- a/drivers/clocksource/vf_pit_timer.c
+++ b/drivers/clocksource/vf_pit_timer.c
@@ -54,7 +54,7 @@ static inline void pit_irq_acknowledge(void)

static u64 pit_read_sched_clock(void)
{
- return __raw_readl(clksrc_base + PITCVAL);
+ return ~__raw_readl(clksrc_base + PITCVAL);
}

static int __init pit_clocksource_init(unsigned long rate)

\
 
 \ /
  Last update: 2014-03-06 12:21    [W:0.060 / U:0.204 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site