Scott McNutt smcnutt@psyent.com wrote:

...

Just wanna to confirm one thing. If one board's SDRAM init was good enough but with poor layout (Layout design or PCB Processing), it would crash like this?

Yes, if your clock signals were not routed cleanly ... but re-check your SDRAM init first.

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.

[snip]

The good part is that u-boot remains stable (due to some handy design decisions) ... and the POST cache tests are a great starting point to determine if the problem exists ... in a deterministic manner ;-)

Really a nice explanation and experience share.

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.

My wild guess is some elements like capacitances don't discharge enough to restore the original state they should be.

U-Boot 1.0.0 (Aug 20 2004 - 21:11:30)   CPU: PPC823EZTnnB2 at 48 MHz: 16 kB I-Cache 8 kB Cache Board: DMTXX DRAM: 128 MB

Code reached to relocate_code()->board_init_r(). Stoped before flash_init().

Does anyone encounter such a problem? Ideas?

Thanks in advance,

Sam

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