[U-Boot] [PATCH] i.MX31: fir imx31_phycore to work after Linux reboot

[Guennadi Liakhovetski]

On Mon, 23 Feb 2009, Sascha Hauer wrote:

> Hi,
> 
> On Sat, Feb 21, 2009 at 10:32:33PM +0100, Wolfgang Denk wrote:
> > Dear Guennadi Liakhovetski,
> > 
> > In message <Pine.LNX.4.64.0902061353280.7686 at axis700.grange> you wrote:
> > > 
> > > > In message <Pine.LNX.4.64.0902061002160.4970 at axis700.grange> you wrote:
> > > > > Upon power on i.MX31 enables most peripheral clocks, Linux disables the ones
> > > > 
> > > > Why does U-Boot do that?
> > > 
> > > i.MX31 does that - the CPU, not U-Boot. I.e., this is the default power-on 
> > > mode.
> > 
> > Yea, but U-Boot performs h/w initialization. So why does it not - like
> > Linux - set sane defaults (with only the necessary clocks enabled) ?
> 
> I simply forgot it. The clock registers do not get resetted on reset,
> only on power up.

Well, it depends. On U-Boot reset they do get resetted, but not on Linux 
reboot. Reason - U-Boot uses the watchdog for reset, Linux just jumps to 
address 0. I tried using watchdog under Linux for reset - it just hung the 
system. You might want to investigate it further...

Thanks
Guennadi
---
Guennadi Liakhovetski, Ph.D.

DENX Software Engineering GmbH,     MD: Wolfgang Denk & Detlev Zundel
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