[U-Boot-Users] SDRAM init problem? Was Re: uboot 1.1.2 problem

[Wolfgang Denk]

In message <20050525083355.6524.qmail at web15904.mail.cnb.yahoo.com> you wrote:
>
> Thanks. Actually, it involves the grey area which a 
> probelm was supposed to produce by hardware or 
> software. The golden role is to check SW first.

You must be one of these hardware guys who always blame the software.
I hope you have your asbestos ready in case you need them soon ;-)


> I have been thinking one puzzle related u-boot itself.
> I noticed that sometimes u-boot would hang after 
> relocation on my board. The chance is slim but have 
> an effect on normal operation. Maybe 1 out of 10 
> times. Especially when power down and on in a short 
> interval like no more than 1 minute. I don't know 
> whether this symptom is due to SDRAM init problem.

This is one of the possible reasons.

> Does anyone encounter such a problem? Ideas?

We've seen lots of "funny" problems with the many boards we lay hands
on. Three more things to check:

* Check the voltages on your system: tolerances ok? spikes  or  other
  noise on the lines? especially close to the CPU?
* Check the clocks. Check the clocks again.
* check for unconnected pins, missing pull-ups or -downs, or incorrect
  resistor values



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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