Where can I find the TS RTC driver mentioned below?
--- In Jim Jackson <> wrote:
>
>
>
>
> On Tue, 9 Jan 2007, gcworrell wrote:
>
> > Hello.
> >
> > On our TS-7300's we have found the hw clock drift to be too large
to
> > support our objectives. To correct this we have replaced the on-
board
> > hw clocks with another. After replacement, on boot, an error
message
> > is displayed indicating the hw clock cannot be accessed using any
known
> > methods. If you manually run the "hwclock" utility with the debug
> > option, it says that /dev/rtc cannot be opened because it doesn't
> > exist. Upon examination, /dev/rtc does not exist.
>
> Have you written a driver for it? AFAIK the Linux Kernel hasn't yet
> been embued with clairvoyance :-)
>
> > What is the mechanism whereby the hw clock is discovered and when
> > is /dev/rtc created? Is there something we need to do to get the
OS to
> > recognize the new clock?
>
> You write a driver for it in the kernel. Check out the TS RTC one
as a
> prototype.
>
> But I have to ask - do you mean the HW clock drift? I may be
teaching my
> grandmother to suck eggs, but when the kernel is running, the HW
clock
> plays no role in timekeeping. The timekeeping is done entirely by
the
> kernel, by setting appropriate timer interrupts etc and corrections.
>
> On shutdown the system time is written to the HW clock, and on boot
the
> kenrel reads to current time from the HW clock - the HW clock drift
would
> affect timing accuracy while the board is powered down.
>
> I know that when the Technologics first ARM board the TS7200 first
came
> out, the kernel timer interrupt config was very poor, and time
keeping was
> very poor while running - being many minutes out per day. I fine
tuned the
> kernel timer interrupt setting and used the adjtimex to fine adjust
the
> kernel timing to better than 1 sec in 5 days (in my pretty constant
temp.
> environment).
>
> cheers
> Jim
>
Yahoo! Groups Links
<*> To visit your group on the web, go to:
http://groups.yahoo.com/group/ts-7000/
<*> Your email settings:
Individual Email | Traditional
<*> To change settings online go to:
http://groups.yahoo.com/group/ts-7000/join
(Yahoo! ID required)
<*> To change settings via email:
<*> To unsubscribe from this group, send an email to:
<*> Your use of Yahoo! Groups is subject to:
http://docs.yahoo.com/info/terms/
|