Hi, This was originally a proposal of mine that I posted back in 2019 as an RFC [1]. The goal is to expose the USB Mode - USB Mode as defined in the USB Type-C and USB Power Delivery specifications - to the user via sysfs. With ports the mode will show the supported and the default USB Mode, which is the mode that is (or should be) used in the next Enter_USB Message. With the partners the mode will show similarly the supported USB modes, and also the active mode. Changing the active mode should cause Data Reset (as described in the USB Power Delivery spec.). This should happen even if there is no active USB Mode (in Alternate Mode). I've modified the original RFC patches based on comments I've received (offline). The major change is that I renamed the sysfs attribute file for the port from "usb_mode" to "usb_capability". I'm taking the USB mode in use in the UCSI driver with these, but I did not add support for the "Set USB" UCSI command yet. I have no way of testing it. Also, I don't really like that we have to construct the Enter_USB Message from the abstracted information that UCSI supplies. The interface should supply the Enter_USB Message that was used as is. [1] https://lore.kernel.org/linux-usb/20191230152857.43917-1-heikki.krogerus@xxxxxxxxxxxxxxx/ Heikki Krogerus (4): usb: typec: Add attribute file showing the supported USB modes of the port usb: typec: Add attribute file showing the USB Modes of the partner usb: typec: ucsi: Supply the USB capabilities to the ports usb: typec: ucsi: Add support for the partner USB Modes Documentation/ABI/testing/sysfs-class-typec | 27 +++ drivers/usb/typec/class.c | 204 +++++++++++++++++++- drivers/usb/typec/class.h | 3 + drivers/usb/typec/ucsi/ucsi.c | 16 ++ drivers/usb/typec/ucsi/ucsi.h | 10 + include/linux/usb/typec.h | 22 +++ 6 files changed, 278 insertions(+), 4 deletions(-) -- 2.45.2
