[PATCH] clocksource/drivers/pistachio: Fix wrong calculated clocksource read value
jszhang at marvell.com
Tue Dec 15 23:11:25 PST 2015
On Tue, 15 Dec 2015 21:59:30 +0100 Daniel Lezcano wrote:
> 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 at marvell.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 ?
I have no HW platforms with pistachio, just read the code and run the
following test code in x86_64 and x86_32:
unsigned long long pistachio_clocksource_read_cycles()
unsigned int counter = 0xf000000;
return ~(unsigned long long)counter;
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