Re: [PATCH v2 02/22] usb: typec: Represent USB4 on the Type-C bus

[Joshua Peisach]

On Sun Sep 6, 2026 at 2:36 PM EDT, Sven Peter wrote:
> USB4 technically isn't alternate mode and entered using the EUDO and has
> no SVID or Discover Modes Response. We can still represent it like an
> altmode on the Type-C bus though by adding a mode kind. Exclude the USB4
> modes from any SVID-specific operations and driver binding, but allow
> consumers to observe their state through notifications.
>
> Like for other altmodes, expose the USB4 mode to sysfs: Add a mode_kind
> to be able to differentiate and then expose the EUDO, make the USB4
> active state read-only since we only represent firmware-negotiated USB4
> modes and omit anything that only applies to SVID-specific altmodes.
>
> Signed-off-by: Sven Peter <sven@xxxxxxxxxx>
> ---
> Hope it's fine to add you as the contact for the sysfs documentation,
> happy to add myself otherwise though.
> ---
>  Documentation/ABI/testing/sysfs-bus-typec | 36 ++++++++++++++
>  drivers/usb/typec/bus.c                   | 67 ++++++++++++++++++++-----
>  drivers/usb/typec/class.c                 | 83 +++++++++++++++++++++++++++----
>  drivers/usb/typec/mode_selection.c        |  6 ++-
>  include/linux/usb/typec.h                 | 20 +++++++-
>  include/linux/usb/typec_altmode.h         | 10 +++-
>  6 files changed, 193 insertions(+), 29 deletions(-)

Reviewed-by: Joshua Peisach <jpeisach@xxxxxxxxxx>