Re: [PATCH] arm64: dts: rockchip: Fix i2c6 clock-frequency on NanoPC-T6

[Diederik de Haas]

On Sat Sep 12, 2026 at 4:16 PM CEST, Diederik de Haas wrote:
> On Sat Sep 12, 2026 at 2:41 PM CEST, Heiko Stuebner wrote:
>> Am Freitag, 11. September 2026, 17:28:33 Mitteleuropäische Sommerzeit schrieb Diederik de Haas:
>>> The i2c6 bus needs to run at 200kHz, because at the default frequency of
>>> 100kHz it may fail to find the RTC resulting in warnings/errors like
>>> 
>>>   rtc-hym8563 6-0051: no valid clock/calendar values available
>>>   rtc-hym8563 6-0051: hctosys: unable to read the hardware clock
>>> 
>>> But only sometimes. This should not happen when there is a battery backing
>>> the RTC, yet it does ... sometimes.
>>
>> I'm confused, shouldn't a slower clock always work?
>> Like I understand how a clock that is too fast can cause issues due
>> to hardware limitations, but running the bus slower somehow shouldn't
>> cause issues?
>
> Impeccable timing ... as I was just about to retract this patch.
>
> So please ignore/drop this and sorry for the noise.

https://github.com/rockchip-linux/kernel/commit/815c9a084e62d700ab5487974b63035e772a29a4
"remove the buf[0] & HYM8563_SEC_VL, it's unsuitable for some hym8563.
set rtc init time for first power on."

I guess I have 'some hym8563' in both my NanoPC-T6 LTS & Plus :-/
The one in my NanoPi R5S works great, so I'll just use/depend on that one.