Hi Greg, On Tue, Oct 26, 2021 at 05:06:28PM +0200, Greg KH wrote: > So, why not sysfs? :) This is about allowing the user space to take over the USB Power Delivery communication and policy decisions in some cases. The user space needs to be able to send and receive raw USB Power Delivery messages one way or the other. I don't care about what's the interface that we use. Here we are talking about the PDOs, so basically the power contract. Even if we figured out a way how to expose all the information from the Capability, Status, Alert and what ever messages you need to the user space via sysfs, and then allow the user to separately send the Request Message, we would have only covered the power contract. That does not cover everything, but it would also be unnecessarily complicated to handle with separate sysfs files IMO. Even with the power contract it would make more sense to me to just allow the user space to simply read and write the raw messages, but when we go the other things like Vendor Specific Messages, I don't think there is any other way. So we really do need to be able to tap into the USB Power Delivery protocol layer directly from user space. I don't care about how we do that - character device is just a suggestion, although, it does still feel correct to me. Is there some other way we could do this? thanks, -- heikki
