ChromeOS UCSI Driver Queued Ahead Of Linux 6.14 Cycle

[phoronix]

Phoronix: ChromeOS UCSI Driver Queued Ahead Of Linux 6.14 Cycle

With the upcoming Linux 6.14 cycle Google is poised to have its ChromeOS UCSI driver upstreamed...

https://www.phoronix.com/news/Linux-6.14-ChromeOS-UCSI

[totoz]

Could someone explain what is USB Platform Policy Manager used for? What interesting stuff could that bring to our desktop?
With some use case examples for this new driver.

[carguello2]

Could someone explain what is USB Platform Policy Manager used for?

According to Microsoft documentation,

USB Type-C Policy Manager monitors the activities of USB Type-C connectors... The Policy Manager gets and coordinates the information from the USB Connector Manager (UCM), USB host controller, and USB function, and your PM client driver. When UI notification is required, the Policy Manager sends the request to system Shell.

https://learn.microsoft.com/en-us/wi...-a-ucsi-driver

https://learn.microsoft.com/en-us/wi...manager-client

[m132]

Sad to see yet another hardware-specific bit shoved into mainline instead of vendors getting their act together and exposing UCSI via ACPI (which Linux has already supported since 2017 via the ucsi_acpi driver).

Could someone explain what is USB Platform Policy Manager used for?.

UCSI is a protocol defined by Intel¹ as an attempt to standardize the way operating systems to talk to USB Type C controllers. Essentially, it lets the OS control what's advertised on the CC1 and CC2 pins of the USB-C connectors, such as the available alternate modes (USB3/USB4/Thunderbolt/DisplayPort/etc.), role (host/device), Power Delivery information, etc. and the negotiation of those parameters.

The PPM in particular sits between the operating system UCSI components and the actual hardware facilitating the CC1/CC2 communication, and orchestrates their work.

From the spec:

The combination of hardware and firmware and any vendor-provided OS software that
provides the interface to all the USB Type-C connectors on the platform is referred to
as the Platform Policy Manager (PPM) in this specification. In addition, there may be
individual policy managers for each USB Type-C connector on the platform. The
individual policy managers are referred to as Local Policy Managers (LPM) in this
specification.

edit: ¹seems like Intel has handed the governance of the spec over to USB-IF since. the new spec is linked in the article

[totoz]

Sad to see yet another hardware-specific bit shoved into mainline instead of vendors getting their act together and exposing UCSI via ACPI (which Linux has already supported since 2017 via the ucsi_acpi driver).

Yeah, that's why I wonder what this new driver provides.

I own a Framework 13, and I can see in logs some "ucsi_acpi USBC000:00: unknown error XXX" or "ucsi_acpi USBC000:00: GET_CABLE_PROPERTY failed (-5)", therefore I assume the UCSI is already driven through ACPI on this computer.
But this laptop also uses the ChromeOS embedded controller, so I will probably see this new driver in action too, but that would make a duplicate driver.