[PATCH v2] i2c: mux: Fix the crash when the i2c-arbitrator node is present

[Michal Simek]

On 6/24/25 05:43, Heiko Schocher wrote:
> Hello Venkatesh Yadav Abbarapu,
> 
> On 23.06.25 10:06, Venkatesh Yadav Abbarapu wrote:
>> Observing the crash when we add the i2c-arbitrator node in the device
>> tree as per the DT bindings. The issue is with the child node of
>> i2c-arbitrator at 72 i.e., i2c at f1950000->i2c-arbitrator at 72->i2c-arb, as the
>> arbitrator uses the uclass of mux(UCLASS_I2C_MUX) and the mux uclass driver
>> checks for the "reg" property using the i2c_mux_child_post_bind() function,
>> if it won't find the "reg" property it will return -EINVAL which is leading
>> to the crash.
>> So, add the logic to check whether the  child node has the "reg" property,
>> if the "reg" property exists then read the "reg" and update the channel.
>>
>> https://www.kernel.org/doc/Documentation/devicetree/bindings/i2c/i2c-arb.txt
>>
>> Signed-off-by: Venkatesh Yadav Abbarapu <venkatesh.abbarapu at amd.com>
>> ---
>> Changes in v2:
>> - Return immediately if "reg" property is missing for arbitrator case.
>> ---
>>   drivers/i2c/muxes/i2c-mux-uclass.c | 5 +++++
>>   1 file changed, 5 insertions(+)
> 
> Reviewed-by: Heiko Schocher <hs at denx.de>
> 
> @Tom: The fix looks valid for me, but I am unsure if it is not to
>        late for 2025.07. What do you think?

No issue to take it to next release. Issue is visible with pca9541 which has 
been sent too but won't make to 2025.07 anyway.

Thanks,
Michal