Messages in this thread Patch in this message | | | Date | Thu, 6 Mar 2014 02:37:20 -0800 | From | tip-bot for Stefan Agner <> | Subject | [tip:timers/urgent] clocksource: vf_pit_timer: use complement for sched_clock reading |
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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)
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