[U-Boot-Users] PXA270 support
r-woodruff2 at ti.com
Thu Mar 17 23:14:50 CET 2005
That was Wolfgang's assertion.
A quick grep of the code seems to indicate that as long as CFG_HZ
represents the number of ticks in a second usage is ok.
HOWEVER, there is a strong chance of overflow depending on the value in
use. Thus 1000 is probably a very save value.
I know for ARM ports I've worked on so far I have always applied almost
the max presaler as I did encounter overflow when validating timing
operations. At that time I just assumed people need to be careful about
assigning CFG_HZ to as small a value as possible, Wolfgang appears to be
taking even a stronger stance.
> -----Original Message-----
> From: u-boot-users-admin at lists.sourceforge.net [mailto:u-boot-users-
> admin at lists.sourceforge.net] On Behalf Of Detlef Vollmann
> Sent: Monday, March 14, 2005 6:03 PM
> To: Wolfgang Denk
> Cc: Woodruff, Richard; u-boot-users at lists.sourceforge.net
> Subject: Re: [U-Boot-Users] PXA270 support
> Wolfgang Denk wrote:
> > CFG_HZ is the number of "clock ticks" per second; it has exactly
> > same meaning as the HZ variable in the Linux kernel.
> > Like in current Linux kernels, U-Boot normally uses a 1
> > system tick, thus CFG_HZ should be 1000.
> And get_timer() should deliver that system tick?
> If so, at least all ARM based CPU ports are "broken"....
> Detlef Vollmann vollmann engineering gmbh
> Linux and C++ for Embedded Systems http://www.vollmann.ch/
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