Calling i2c set speed twice for i2c_mux_bus

Heiko Schocher hs at
Fri Apr 10 07:11:29 CEST 2020

Hello Michal,

Am 09.04.2020 um 16:03 schrieb Michal Simek:
> Hi Heiko and Simon,
> I have find out one bug in i2c class. I am using zcu104 revC board which
> has dts in mainline where i2c1 has i2c mux with some channels.
> In DT clock-frequency = <400000>; is specified and it is read in
> i2c_post_probe(). But i2c_mux_bus_drv is also UCLASS_I2C which means
> that post probe is called for it too. And because clock-frequency
> property is not there default 100k is used.
> I think that is bug and should be fixed.
> Heiko: Are you aware about this issue?

No :-(

The question is, is this a bug?

Should a i2c bus behind a mux not be able to set his own speed?

But may as a feature (or bugfix?) if "clock-frequency" is not there,
use the speed of the parent bus...?

> Simon: I think that make sense to use some flags to skip calling
> post_probe in this case. Or any suggestion how to fix it would be great.
> Thanks,
> Michal

DENX Software Engineering GmbH,      Managing Director: Wolfgang Denk
HRB 165235 Munich, Office: Kirchenstr.5, D-82194 Groebenzell, Germany
Phone: +49-8142-66989-52   Fax: +49-8142-66989-80   Email: hs at

More information about the U-Boot mailing list