linux-kernel - Re: [PATCH] clocksource/drivers/pistachio: Fix wrong calculated clocksource read value

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Message-ID: <56707F32.3030405@linaro.org>
Date:	Tue, 15 Dec 2015 21:59:30 +0100
From:	Daniel Lezcano <daniel.lezcano@...aro.org>
To:	Jisheng Zhang <jszhang@...vell.com>, tglx@...utronix.de
Cc:	linux-kernel@...r.kernel.org, linux-arm-kernel@...ts.infradead.org
Subject: Re: [PATCH] clocksource/drivers/pistachio: Fix wrong calculated
 clocksource read value

On 11/25/2015 04:42 PM, Jisheng Zhang wrote:
> 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@...vell.com>

Hi Jisheng,

I tried to reproduce this behavior on x86_64 but without success.

On which architecture did you produce this result ? Do you have a simple 
test program to check with ?

Thanks

   -- Daniel


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