Re: nested I2C muxes

[Adrian Fiergolski <Adrian.Fiergolski@cern.ch>]

Hi Peter,

Thank you for your answers.

Yes, the typos you noticed (<5>, the same switch address) , are just
because I didn't prepare an example device tree carefully enough.

I will debug further from where my problem comes from.

Regards,
Adrian

On 19.01.2017 at 23:50, Peter Rosin wrote:
> On 2017-01-19 19:34, Peter Rosin wrote:
>> On 2017-01-19 19:03, Adrian Fiergolski wrote:
>>> Hi,
>>>
>>> I haven't found any information regarding support for nested i2c muxes.
>>> Is the below device tree supported by the current driver ?
>> No, it is not since you cannot have two devices with address 0x74
>> visible at the same time. You would have to set a different address
>> on one of the muxes using its A0-A2 pins. Then it should work.
>>
>> Look in Documentation/i2c/i2c-topology for more information.
>>
>> Cheers,
>> peda
>>
>>> &i2c0 {
>>>         status = "okay";
>>>         clock-frequency = <400000>;
>>>         pinctrl-names = "default";
>>>         pinctrl-0 = <&pinctrl_i2c0_default>;
>>>
>>>         i2cswitch@74 {
>>>                 compatible = "nxp,pca9548";
>>>                 #address-cells = <1>;
>>>                 #size-cells = <0>;
>>>                 reg = <0x74>;
>>>
>>>                 i2c@0 {
>>>                         #address-cells = <1>;
>>>                         #size-cells = <0>;
>>>                         reg = <0>;
>>>                         si570: clock-generator@5d {
>>>                                 #clock-cells = <0>;
>>>                                 compatible = "silabs,si570";
>>>                                 temperature-stability = <50>;
>>>                                 reg = <0x5d>;
>>>                                 factory-fout = <156250000>;
>>>                                 clock-frequency = <148500000>;
>>>                         };
>>>                 };
>>>
>>>                 i2c@2 {
>>>                         #address-cells = <1>;
>>>                         #size-cells = <0>;
>>>                         reg = <5>;
> Also, this <5> is bogus. It should match the @2 a few lines up.
>
> Cheers,
> peda
>
>>>                         i2cswitch_hpc@74 {
>>>                                 compatible = "nxp,pca9548";
>>>                                 #address-cells = <1>;
>>>                                 #size-cells = <0>;
>>>                                 reg = <0x74>;
>>>                                 hpc_caribou_sources_enable@76  {
>>>                                         compatible= "nxp,pca9539";
>>>                                         #address-cells = <1>;
>>>                                         #size-cells = <0>;
>>>                                         reg = <0x76>;
>>>                                 };
>>>                         };
>>>
>>>                 };
>>>
>>>         };
>>>
>>> };
>>>
>>> With such tree I am getting error
>>>
>>> [2.173385] i2c i2c-2: of_i2c: invalid addr=0 on
>>> /amba/i2c@e0004000/i2cswitch@74/i2c@2/i2cswitch_hpc@74
>>>
>>>
>>> Regards,
>>>
>>> Adrian Fiergolski
>>>
>>>
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