[U-Boot] [PATCH 1/2] i.MX28: Fix ref_cpu clock setup

[Marek Vasut <marek.vasut@gmail.com>]

> Hi,
> 
> This patch fixes ref_cpu clock setup. This bug leads to a hanging board
> after rebooting from the Kernel, due to failing memory size detection:
> U-Boot 2011.12-svn342 (Feb 02 2012 - 17:20:00)
> 
> Freescale i.MX28 family
> I2C:   ready
> DRAM:  0 Bytes
> 
> The cause of the bug is register hw_clkctrl_frac0 being accessed as
> a 32-bit long, whereas the manual specifically states it can be accessed
> as bytes only.
> Applying this patch fixes this problem.
> 
> Signed-off-by: Robert Delien (robert at delien.nl)

Hi,

I was thinking of this and we might need to introduce either special accessor 
for this particular register or rework include/regs-common.h and introduce 
mx28_reg_8 (which I don't think is a good idea).

So Robert, what do you think about introducing a special accessor in 
include/regs-clkctrl for FRAC0/1? This though introduces a problem with usage of 
_set, _clk and _tog accesses, which might need a little thinking through.

Thanks for this patch, you really did a good share of research on this one.

M

> 
> ________________________________________
> From: Marek Vasut [marek.vasut at gmail.com]
> Sent: 26 January 2012 19:32
> To: Fabio Estevam
> Cc: Robert Deli?n; u-boot at lists.denx.de
> Subject: Re: mx28 spl power cpu clock configuration
> 
> > Hi Robert,
> > 
> > On 1/25/12, Marek Vasut <marek.vasut@gmail.com> wrote:
> > >> Shouldn't we configure clkctrl_frac0 - or at least disable CPU clock
> > >> gating - before disabling PLL bypass?
> > > 
> > > This seems reasonable. Fabio, can you comment?
> > 
> > Could you please post a patch with your proposed change so that we can
> > test it?
> 
> Hi Fabio,
> 
> I bought a really crappy custom board a few days ago (some china-made crap)
> sporting mx287, but apparently I'm hitting similar issue you do here.
> 
> When I swap power_init and mem_init though, the board boots fine, othervise
> it hangs.
> 
> M