[U-Boot-Users] [Patch 02/17 Try 2] U-Boot-V2:Common:Clock Handle caseofclockrollover for get_time_ns

Menon, Nishanth
2008-06-03T16:27:04Z

Sascha,
> -----Original Message-----
> From: Sascha Hauer [mailto:s.hauer at pengutronix.de]
> Sent: Tuesday, June 03, 2008 10:14 AM
> To: Menon, Nishanth
> Cc: u-boot-users at lists.sourceforge.net; Laurent Desnogues; dirk.behme at googlemail.com;
> philip.balister at gmail.com; Gopinath, Thara; Kamat, Nishant; Syed Mohammed, Khasim
> Subject: Re: [Patch 02/17] U-Boot-V2:Common:Clock Handle caseofclockrollover for get_time_ns
>
> > Output will be:
> > delta1=0xFFFFFFF8 maskdelta1=0x0000FFF0 delta2=0x00000000
> >
> > What we will get now is maskdelta1, while delta2 is the right value.
>
> It's not that I thought of the code by myself, I just looked into the
> kernel and it's exactly like this in the kernel code. So you either just
> found a kernel bug or we both understand something wrong.

Here is a revisit of this patch. The change will ensure cycle_now and last will be masked.

Signed-off-by: Nishanth Menon<x0nishan@ti.com>

---
common/clock.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

Index: u-boot.v2/common/clock.c
===================================================================
--- u-boot.v2.orig/common/clock.c 2007-10-10 21:50:14.000000000 -0500
+++ u-boot.v2/common/clock.c 2008-06-03 11:16:05.000000000 -0500
@@ -41,7 +41,7 @@
uint64_t ns_offset;

/* read clocksource: */
- cycle_now = cs->read();
+ cycle_now = cs->read() & cs->mask;

/* calculate the delta since the last call: */
cycle_delta = (cycle_now - cs->cycle_last) & cs->mask;