Joakim Tjernlund/Transmode wrote on 2013/01/24 09:40:45:

From: Joakim Tjernlund/Transmode To: Mats Kärrman Mats.Karrman@tritech.se, Cc: "u-boot@lists.denx.de" u-boot@lists.denx.de, Wolfgang Denk

wd@denx.de

Date: 2013/01/24 09:40 Subject: RE: [U-Boot] mpc512x: Trouble migrating from 2012.07 to 2013.01

Mats Kärrman Mats.Karrman@tritech.se wrote on 2013/01/23 22:58:56:

...

Dear Wolfgang Denk,

...

...

Found that it was looping endlessly in

arch/powerpc/lib/ticks.S::wait_ticks

...

(). Reverting commit "ppc: Create a stack frame for wait_ticks()" made

...

everything work again.

...

This makes no sense to me - especially as it works on all other systems.

Me neither, there is not a lot details. I do recall having other

problems with

wait_ticks from time to time, sometimes the TB counter(mtfbu, mftb in

get_ticks)

would not increment so one would just loop forever in wait_ticks. This

problem

had nothing to do with my patch though. Never got around to finding out what caused it, we ended up blaming

unstable HW.

Some ideas though:

• Perhaps you have some alignment problem, try adding nop's here and

there.

• My patch uses r0(which is what one should use to make gdb happy)

instead of r8

to stash the LR. Possibly you have some odd dependency on r0, try

using r8 again.

Try getting LR from stack instead of trusting r0 to be valid: - mtlr r0 /* restore link register */ + lwz r0, 20(r1) /* restore link register */ + mtlr r0 This is what one should do but as we have complete control of r0 here we don't need to.

hmm, do you have WATCHDOG_RESET defined? does it use r0? I guess the above patch would make wait_ticks safer from accidental use by WATCHDOG_RESET, if it works for you, please send a proper patch to u-boot.

Jocke