Re: [PATCH v2 0/2] firmware: arm_scmi: Ensure automatic module loading

[Hans de Goede]

Hi,

On 9-Jul-26 16:37, Sudeep Holla wrote:
> On Thu, Jul 09, 2026 at 04:31:00PM +0200, Hans de Goede wrote:
>> Hi,
>>
>> On 9-Jul-26 16:21, Sudeep Holla wrote:
> [...]
>>>
>>> I need to recall why we moved from static list of devices to dynamic.
>>> One reason I can think right now is the vendor protocols and their drivers
>>> But in general it was an attempt to help multiple drivers bind to different
>>> scmi_devices that have same protocol ID. E.g. the performance protocol
>>> can be used by cpufreq and devfreq/performance genpd drivers.
>>
>> Note it is ok to have multiple drivers bind to the same modalias,
>> depending on the reason why there are multiple drivers either one
>> should detect that it is not compatible and exit probe() with -ENODEV
>> or there should be some other mechanism to make sure only one driver
>> loads.
>>
>> E.g. duplicate USB device-ids happen (they shouldn't but they do) and
>> then the drivers typically figure out if they are talking to the device
>> which they were written for, or the other device with the same USB-ids
>> and then one of the 2 drivers exits with -ENODEV.
>>
> 
> Understood. Sorry I tried to explain with examples assuming you may not
> be aware of the details, but now reading your response, you have better
> examples.
> 
>>>> I wonder if we can just move a small part of the drivers
>>>> (some mapping table) into the bus code and then just have this work as it
>>>> does on regular busses. I hope to be able to make some time to look into
>>>> this soonish.
>>>>
>>>
>>> I started with that few years ago and we then moved to this dynamic
>>> device creation. But I agree if it is deviation from the norms(which I
>>> wasn't aware of at the time), we can remove it.
>>
>> Looking at the issue this is causing for automatic module loading if we
>> can get back to the bus enumeration code always creating a device without
>> waiting for the driver kmod to load then that would be good IMHO.
>>
> 
> Sure if it fixes the issue for you. Cristian can point out anything I
> might have missed to consider as he is the one who reworked it and made
> it dynamic device creation which at the time sounded nice option to
> solve the issue. We weren't aware that it could cause such issues 🙁.

Note that before patch 1/2 of this series we did not have working
module-autoloading for SCMI modules at all. With that said yes it would
be nice to get this working.

Can you provide a patch for this to try ?

Regards,

Hans