[U-Boot-Users] comment in mpc8xx - cpu_init.c - line 76

[U-Boot-Users] comment in mpc8xx - cpu_init.c - line 76

[Peter Asemann]

Line 76 in the most up-to-date version of 
.../u-boot/cpu/mpc8xx/cpu_init.c tells me NOT to change EBDF.
Do I need to stick to this... advice?

The Hard Reset Configuration word of my MPC875-powered hardware is 
hard-wired to set the SCCR[EBDF] to 01 (half bus speed) at hard reset in 
the moment.
I had hoped that I could change SCCR[EBDF] to 00 (full bus speed) via 
software if needed.

So - is the comment in the code some kind of serious warning, for the 
CPU will burn or crash if I try to change EBDF via software, or may I 
ignore it? I'd need the hardware guys to put in some additional jumper 
in case I can't change SCCR[EBDF] by software for some reason.

Thanks for your time,

Peter Asemann

[U-Boot-Users] comment in mpc8xx - cpu_init.c - line 76

[Wolfgang Denk]

Dear Peter,

in message <41FA5969.4050107@web.de> you wrote:
> Line 76 in the most up-to-date version of 
> .../u-boot/cpu/mpc8xx/cpu_init.c tells me NOT to change EBDF.
> Do I need to stick to this... advice?

No - if you know _exactly_ what you're doing.

> So - is the comment in the code some kind of serious warning, for the 
> CPU will burn or crash if I try to change EBDF via software, or may I 
> ignore it? I'd need the hardware guys to put in some additional jumper 

You must not ignore it. You have to understand  what  it  means;  for
reference see "cpu/mpc8xx/speed.c"


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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