[U-Boot] [PATCH] powerpc: do not fixup NULL ptrs

[Joakim Tjernlund]

Andre Schwarz <andre.schwarz at matrix-vision.de> wrote on 2010/11/04 15:49:06:
>
> Jocke,
>
> >> CPU:   e300c4, MPC8379, Rev: 2.1 at 600 MHz, CSB: 400 MHz
> >>
> >> - Boot from NOR Flash
> >> - HRCW from I2C EEPROM
> >> - Reset Vector 0x100, i.e. low boot.
> >>
> > OK, almost the same as me, but I got a:
> > CPU:   e300c2, MPC8321, Rev: 1.1 at 266.664 MHz, CSB: 133.332 MHz
> >
> > However, I think I just found the problem.
> >
>
> excellent !
>
> > My tree is a bit messy now so no patch but it will be:
> >
> > Stick an isync (or sync) in
> > map_flash_by_law1
> > ....
> >    stw r4, LBLAWAR1(r3) /* LBLAWAR1<= 8MB Flash Size */
> >    isync //HERE !! HERE !! HERE
> >    blr
> >
>
> ok - works for me, i.e. no quad-nop needed anymore.

Does both your boards work now?

>
> > I am guessing it takes a while for the stw r4, LBLAWAR1(r3)
> > to hit the HW so one must wait for it, not sure what is
> > best though, sync or isync?
> >
> If it is a timing issue why should have the nops influenced this ?
> I still wonder if this is the real problem and whether we might need
> more (i)syncs elsewhere ...

You can try replacing the isync with 4 nops. That works
for me. moving the 4 nops after the blr doesn't work.

I think it worked earlier by chance but the removal of
the flags changed timing, probably a cache line crossing
at the wrong place.

     Jocke