[U-Boot-Users] CFG_HZ and CFG_SCCR question

[U-Boot-Users] CFG_HZ and CFG_SCCR question

[Peter Asemann]

1. There is a CFG_HZ configuration setting in many config files, but 
it's not mentioned in the README.
The source code of components where it is used suggests it has to do 
with timer issues.

Having thought and done some "research" on that matter I do believe now 
that the CFG_HZ setting must have something to do with the expiry of 
some timer, but probably doesn't set the tmbclk/tbclk but some counter 
to have some timer expire every CFG_HZ times per second. Is that right?

2. Whilst taking a look in the MPC875 documentation I found there are 
system registers I'd like to take influence on to make sure there are 
the "right" values in them. For example the SCCR. I saw that in the 
README SCCR is mentioned:

- CFG_SCCR:     System Clock and reset Control Register (15-27)

So I suppose by defining CFG_SCCR as something I assign the value of 
something to the register and therefore set the registers content.

But what do the numbers (the range?) in the braces mean?

Best regards and thanks for reading,

Peter Asemann

[U-Boot-Users] CFG_HZ and CFG_SCCR question

[Wolfgang Denk]

In message <41B7202D.9070508@web.de> you wrote:
> 1. There is a CFG_HZ configuration setting in many config files, but 
> it's not mentioned in the README.

Please consider CFG_HZ to be a constant with the value of 1000.

> Having thought and done some "research" on that matter I do believe now 
> that the CFG_HZ setting must have something to do with the expiry of 
> some timer, but probably doesn't set the tmbclk/tbclk but some counter 
> to have some timer expire every CFG_HZ times per second. Is that right?

Something like that. It's the system tick, similar  to  the  constant
"HZ" in the Linux kernel.

> - CFG_SCCR:     System Clock and reset Control Register (15-27)
...
> But what do the numbers (the range?) in the braces mean?

It's a reference to page 15-27 in the MPC860 User's Manual.

Best regards,

Wolfgang Denk

-- 
Software Engineering:  Embedded and Realtime Systems,  Embedded Linux
Phone: (+49)-8142-66989-10 Fax: (+49)-8142-66989-80 Email: wd at denx.de
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