[U-Boot] [PATCH 2/5] ARM: arm926ejs: fix lowlevel_init call

[Chris Packham]

On Mon, May 7, 2018 at 10:11 PM Måns Rullgård <mans at mansr.com> wrote:

> Chris Packham <judge.packham at gmail.com> writes:

> > Hi Mans, Stefano,
> >
> > On Fri, Apr 27, 2018 at 9:00 PM Stefano Babic <sbabic at denx.de> wrote:
> >
> >> On 21/04/2018 17:11, Mans Rullgard wrote:
> >> > The code attempts to preserve the value of LR by storing it in R12/IP
> >> > across the lowevel_init() call.  However, this register is not saved
> >> > by the callee.  Use a register that guaranteed to be preserved
instead.
> >> >
> >> > Signed-off-by: Mans Rullgard <mans at mansr.com>
> >> > ---
> >> >  arch/arm/cpu/arm926ejs/start.S | 4 ++--
> >> >  1 file changed, 2 insertions(+), 2 deletions(-)
> >> >
> >> > diff --git a/arch/arm/cpu/arm926ejs/start.S
> > b/arch/arm/cpu/arm926ejs/start.S
> >> > index 959d1ed86d8a..a6f0bdb70345 100644
> >> > --- a/arch/arm/cpu/arm926ejs/start.S
> >> > +++ b/arch/arm/cpu/arm926ejs/start.S
> >> > @@ -105,9 +105,9 @@ flush_dcache:
> >> >       /*
> >> >        * Go setup Memory and board specific bits prior to relocation.
> >> >        */
> >> > -     mov     ip, lr          /* perserve link reg across call */
> >> > +     mov     r4, lr          /* perserve link reg across call */
> >> >       bl      lowlevel_init   /* go setup pll,mux,memory */
> >> > -     mov     lr, ip          /* restore link */
> >> > +     mov     lr, r4          /* restore link */
> >> >  #endif
> >> >       mov     pc, lr          /* back to my caller */
> >> >  #endif /* CONFIG_SKIP_LOWLEVEL_INIT */
> >> >
> >
> >> Applied to u-boot-imx, thanks !
> >
> > I think this might be causing me a problem on a Marvell Kirkwood board
I'm
> > working on getting into upstream. It may also be problematic for orion5x
> > boards. Both of these use r4 in lowlevel_init.

> I've just sent an untested patch for orion5x.


Thanks for that.