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From: Jisheng Zhang <jszhang@marvell.com>
To: <daniel.lezcano@linaro.org>, <tglx@linutronix.de>
Cc: <linux-kernel@vger.kernel.org>,
	<linux-arm-kernel@lists.infradead.org>,
	Jisheng Zhang <jszhang@marvell.com>
Subject: [PATCH] clocksource/drivers/pistachio: Fix wrong calculated clocksource read value
Date: Wed, 25 Nov 2015 23:42:49 +0800	[thread overview]
Message-ID: <1448466169-5230-1-git-send-email-jszhang@marvell.com> (raw)

Let's assume the counter value is 0xf000000, the pistachio clocksource
read cycles function would return 0xffffffff0fffffff, but it should
return 0xfffffff.

We fix this issue by calculating bitwise-not counter, then cast to
cycle_t.

Signed-off-by: Jisheng Zhang <jszhang@marvell.com>
---
 drivers/clocksource/time-pistachio.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/clocksource/time-pistachio.c b/drivers/clocksource/time-pistachio.c
index bba6799..3269d9e 100644
--- a/drivers/clocksource/time-pistachio.c
+++ b/drivers/clocksource/time-pistachio.c
@@ -84,7 +84,7 @@ pistachio_clocksource_read_cycles(struct clocksource *cs)
 	counter = gpt_readl(pcs->base, TIMER_CURRENT_VALUE, 0);
 	raw_spin_unlock_irqrestore(&pcs->lock, flags);
 
-	return ~(cycle_t)counter;
+	return (cycle_t)~counter;
 }
 
 static u64 notrace pistachio_read_sched_clock(void)
-- 
2.6.2


             reply	other threads:[~2015-11-25 15:47 UTC|newest]

Thread overview: 14+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2015-11-25 15:42 Jisheng Zhang [this message]
2015-12-15 20:59 ` [PATCH] clocksource/drivers/pistachio: Fix wrong calculated clocksource read value Daniel Lezcano
2015-12-16  7:11   ` Jisheng Zhang
2015-12-16  7:28     ` Jisheng Zhang
2015-12-16  7:36       ` Jisheng Zhang
2015-12-16  7:49         ` Jisheng Zhang
2015-12-16  9:21         ` Daniel Lezcano
2015-12-16  9:33           ` Russell King - ARM Linux
2015-12-16 10:32             ` Daniel Lezcano
2015-12-16 10:38               ` Russell King - ARM Linux
2015-12-16 16:23                 ` Daniel Lezcano
2015-12-17  9:07                 ` Jisheng Zhang
2015-12-16  9:01       ` Daniel Lezcano
2015-12-16  9:02     ` Daniel Lezcano

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