| From 224aa3ed45c8735ae02bb2ecca002409fa6aa772 Mon Sep 17 00:00:00 2001 |
| From: Stefan Agner <stefan@agner.ch> |
| Date: Wed, 5 Mar 2014 23:11:08 +0100 |
| Subject: clocksource: vf_pit_timer: use complement for sched_clock reading |
| |
| From: Stefan Agner <stefan@agner.ch> |
| |
| commit 224aa3ed45c8735ae02bb2ecca002409fa6aa772 upstream. |
| |
| 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 |
| Signed-off-by: Thomas Gleixner <tglx@linutronix.de> |
| Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> |
| |
| --- |
| drivers/clocksource/vf_pit_timer.c | 2 +- |
| 1 file changed, 1 insertion(+), 1 deletion(-) |
| |
| --- a/drivers/clocksource/vf_pit_timer.c |
| +++ b/drivers/clocksource/vf_pit_timer.c |
| @@ -54,7 +54,7 @@ static inline void pit_irq_acknowledge(v |
| |
| 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) |
