[U-Boot] [PATCH] sunxi: set the default CPUx frequency of H5 to 816MHz

[icenowy at aosc.io]

在 2017-10-31 15:57，Jagan Teki 写道：
> On Tue, Oct 31, 2017 at 5:06 AM, Icenowy Zheng <icenowy at aosc.io> wrote:
>> Some H5 boards are designed to start at 1.1V CPUx voltage (e.g. Nano 
>> Pi
>> NEO2), which may not work properly at 1008MHz if the chip's quality is
>> not so good.
>> 
>> Lower the default CPUx frequency of H5 to 816MHz.
>> 
>> Signed-off-by: Icenowy Zheng <icenowy at aosc.io>
>> ---
>>  arch/arm/mach-sunxi/Kconfig | 2 +-
>>  1 file changed, 1 insertion(+), 1 deletion(-)
>> 
>> diff --git a/arch/arm/mach-sunxi/Kconfig b/arch/arm/mach-sunxi/Kconfig
>> index 09cfec6f57..1fededd0a3 100644
>> --- a/arch/arm/mach-sunxi/Kconfig
>> +++ b/arch/arm/mach-sunxi/Kconfig
>> @@ -397,9 +397,9 @@ config SYS_CLK_FREQ
>>         default 1008000000 if MACH_SUN5I
>>         default 1008000000 if MACH_SUN6I
>>         default 912000000 if MACH_SUN7I
>> +       default 816000000 if MACH_SUN50I || MACH_SUN50I_H5
>>         default 1008000000 if MACH_SUN8I
> 
> Even orangepi pc2 has 1.1v after power-on and it's work fine [1] did
> you find an issue with neo2?

Yes, the boot process randomly hang at SPL stage -- but when it enters
ATF it will run smoothly as the ATF will re-configure CPUx frequency
to 816MHz.

According to the official operating point table [2], 1008MHz is bound
to 1.2V, and 816MHz is bound to 1.1V.

Allwinner chips usually have not-so-good quality control to reach the
low price, and different chips may work differently in situations
that is beyond the official the OPP table.

[2] 
https://github.com/OrangePiLibra/OrangePi_H5SDK/blob/master/external/sys_config.fex#L1367

> 
> [1] http://linux-sunxi.org/Xunlong_Orange_Pi_PC_2#CPU_clock_speed_limit
> 
> thanks!