Re: [PATCH RFC 00/12] arm64: mediatek: Add M.2 E-key slot on Chromebooks

[Bartosz Golaszewski]

On Wed, 27 May 2026 19:41:30 +0200, Greg Kroah-Hartman
<gregkh@xxxxxxxxxxxxxxxxxxx> said:
> On Wed, May 27, 2026 at 06:21:00PM +0200, Chen-Yu Tsai wrote:

...

>>
>> However this seems to completely decouple the power sequencing from the
>> USB core. Take the USB A connector for example, it was recently added to
>> the onboard USB devices driver. However the connector has a device node
>> that is not a child node of any USB host controller or hub; it is connected
>> through OF graph. At the same time, since it typically sits at the top
>> level of the device tree, a platform device is directly created and the
>> driver subsequently binds to that device. This is totally different from
>> how the hub and other directly connected onboard USB devices work. In
>> the onboard device case, the device node is a child node of the USB hub
>> or controller, and the corresponding platform device only gets created
>> when the USB hub driver probes, thereby sort of tying it into the USB
>> device topology.
>
> Hm, did we mess this up?  If so, we can always change it if you think
> this should be done differently.
>
> Hubs should be dealing with the power issues for their ports, so maybe
> rethinking this might be wise.  I'm just loath to add hardware-specific
> hacks to the hub common code for obvious reasons.  Anything we can do to
> pull it out to a separate driver is best so it doesn't affect the 99% of
> the users that don't have that crazy hardware :)
>

IIUC what we discussed with Chen-Yu yesterday, the only thing that needs to be
done in the USB hub driver is attaching the port firmware nodes (if present) to
the port devices we instantiate. The rest can be handled elsewhere.

Chen-Yu: correct me if I'm wrong.

Bartosz