linux-kernel - Re: [PATCH v2 05/10] usb: typec: Implement automated mode selection

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Message-ID: <CAMMMRMf_qc342=azkU-ceg=f-db2Z9NiONOu1_oRk8tmRL4RGg@mail.gmail.com>
Date: Thu, 24 Jul 2025 10:39:00 +0200
From: Andrei Kuchynski <akuchynski@...omium.org>
To: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Cc: Heikki Krogerus <heikki.krogerus@...ux.intel.com>, 
	Abhishek Pandit-Subedi <abhishekpandit@...omium.org>, Benson Leung <bleung@...omium.org>, 
	Jameson Thies <jthies@...gle.com>, Tzung-Bi Shih <tzungbi@...nel.org>, linux-usb@...r.kernel.org, 
	chrome-platform@...ts.linux.dev, Guenter Roeck <groeck@...omium.org>, 
	Dmitry Baryshkov <lumag@...nel.org>, "Christian A. Ehrhardt" <lk@...e.de>, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2 05/10] usb: typec: Implement automated mode selection

Proposed sysfs entries for V3:

- portN/portN.M/priority, RW.
This attribute assigns a unique priority to each mode. If a user
attempts to input a value that is already in use, the existing mode at
that priority will have its priority incremented by one to accommodate
the new input. Users cannot disable a mode via this entry; disabling
is handled by `active` for altmodes and `usb_capability` for USB4 mode

- portN/mode_priorities, RO.
Provides a prioritized list of all available modes for the port,
formatted as a space-separated string (e.g., "USB4 TBT DP").

- portN-partner/mode_selection, RW.
Write: 1/0 to trigger or cancel mode selection.
Read:  Provides a prioritized list of all available modes for the
partner. Modes currently in progress are indicated by parentheses
(e.g., "USB4 (TBT) DP"). Active modes are enclosed in brackets
(e.g., "USB4 [TBT] DP").

- portN-partner.M/entry_result, RO.
Represents a mode state for this altmode, e.g. "none", "active",
"in progress", "cable error", "timeout".

- portN/usb4_priority, RW.
- portN-partner/usb4_entry_result, RO.
USB4 mode, not being part of `typec_altmode_group`, introduces
additional attributes with the same meaning as alternate modes
attributes.

Please let me know if you have any questions, require further
clarification on these proposed sysfs entries, or have objections to
them.

Thanks,
Andrei