[U-Boot] [PATCH] armv8/fsl-layerscape: fdt: remove SYSCLK frequency fixup for ls1012a

[Scott Wood]

On Fri, 2017-01-20 at 16:28 +0000, york sun wrote:
> On 01/19/2017 07:34 PM, Yangbo Lu wrote:
> > 
> > Generally SYSCLK frequency is dependent on on-board switch settings.
> > It may vary as per requirement, but this doesn't apply to ls1012a.
> > ls1012a has its SYSCLK frequencies specified in the RM. The fixup
> > for all 'fixed-clock' compatibles of ls1012a would cause incorrect
> > SYSCLK frequency values. So remove the SYSCLK frequency fixup for ls1012a.
> > 
> > Fixes: 6f14e25 ("armv8: fsl-lsch3: fixup SYSCLK frequency in device tree")
> > Signed-off-by: Yangbo Lu <yangbo.lu at nxp.com>
> > ---
> >  arch/arm/cpu/armv8/fsl-layerscape/fdt.c | 2 ++
> >  1 file changed, 2 insertions(+)
> > 
> > diff --git a/arch/arm/cpu/armv8/fsl-layerscape/fdt.c
> > b/arch/arm/cpu/armv8/fsl-layerscape/fdt.c
> > index c10ccf9..e59c232 100644
> > --- a/arch/arm/cpu/armv8/fsl-layerscape/fdt.c
> > +++ b/arch/arm/cpu/armv8/fsl-layerscape/fdt.c
> > @@ -161,8 +161,10 @@ void ft_cpu_setup(void *blob, bd_t *bd)
> >  			       "clock-frequency", CONFIG_SYS_NS16550_CLK,
> > 1);
> >  #endif
> > 
> > +#ifndef CONFIG_ARCH_LS1012A
> >  	do_fixup_by_compat_u32(blob, "fixed-clock",
> >  			       "clock-frequency", CONFIG_SYS_CLK_FREQ,
> > 1);
> > +#endif
> > 
> >  #ifdef CONFIG_PCI
> >  	ft_pci_setup(blob, bd);
> > 
> Yangbo,
> 
> Why fixing up this clock causes incorect frequency value? The macro 
> CONFIG_SYS_CLK_FREQ is defined as 125MHz for ls1012a.

Because ls1012a has two different input frequencies -- 125 MHz for the
platform PLL and 100 MHz for the core PLLs.  When we added a second fixed-
clock node for the latter, U-Boot was overwriting it.

While the ifdef solves this immediate problem, it doesn't fix the underlying
problem that this fixup is overly broad.  It should identify the specific node
it's looking for, and not overwrite every fixed-clock node it finds.

-Scott