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

[york sun]

On 01/20/2017 01:36 PM, Scott Wood wrote:
> 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.
>

So current code tries to fix up any node with "fixed-clock"? That's not 
good. What if we have multiple fixed clocks?

York