From mboxrd@z Thu Jan 1 00:00:00 1970 From: daniel.lezcano@linaro.org (Daniel Lezcano) Date: Fri, 18 Dec 2015 15:18:15 +0100 Subject: [PATCH 62/69] clocksource/drivers/pistachio: Fix wrong calculated clocksource read value In-Reply-To: <1450448302-27429-1-git-send-email-daniel.lezcano@linaro.org> References: <5672CB9E.7090707@linaro.org> <1450448302-27429-1-git-send-email-daniel.lezcano@linaro.org> Message-ID: <1450448302-27429-62-git-send-email-daniel.lezcano@linaro.org> To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org From: Jisheng Zhang Let's assume the counter value is 0xf0000000, the pistachio clocksource read cycles function should return ~0x0fffffff but actually it returns 0xffffffff0fffffff. That occurs because: ~(cycle_t)value is different from (cycle_t)~value. unsigned long val = ~(unsigned long)0xf0000000; 40049a: 48 b8 ff ff ff 0f ff movabs $0xffffffff0fffffff,%rax unsigned long val = (unsigned long)~0xf0000000; 40049a: 48 c7 45 f8 ff ff ff movq $0xfffffff,-0x8(%rbp) We fix this issue by calculating bitwise-not counter, then cast to cycle_t. Signed-off-by: Jisheng Zhang Signed-off-by: Daniel Lezcano --- 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) -- 1.9.1