linux-kernel - [PATCH 00/10] USB Type-C mode selection

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Message-ID: <20250616133147.1835939-1-akuchynski@chromium.org>
Date: Mon, 16 Jun 2025 13:31:37 +0000
From: Andrei Kuchynski <akuchynski@...omium.org>
To: Heikki Krogerus <heikki.krogerus@...ux.intel.com>,
	Dmitry Baryshkov <lumag@...nel.org>,
	Abhishek Pandit-Subedi <abhishekpandit@...omium.org>,
	Jameson Thies <jthies@...gle.com>,
	Benson Leung <bleung@...omium.org>,
	Tzung-Bi Shih <tzungbi@...nel.org>
Cc: Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	Guenter Roeck <groeck@...omium.org>,
	Pooja Katiyar <pooja.katiyar@...el.com>,
	Badhri Jagan Sridharan <badhri@...gle.com>,
	RD Babiera <rdbabiera@...gle.com>,
	linux-usb@...r.kernel.org,
	linux-kernel@...r.kernel.org,
	chrome-platform@...ts.linux.dev,
	Andrei Kuchynski <akuchynski@...omium.org>
Subject: [PATCH 00/10] USB Type-C mode selection

This patch series introduces a flexible mechanism for USB Type-C mode
selection, enabling into USB4 mode, Thunderbolt alternate mode, or
DisplayPort alternate mode.
Two new sysfs attributes are exposed to provide user control over mode
selection:
`altmode_priorities`: Allows users to define their preferred order for
attempting mode entry.
`mode_selection`: Initiates an automatic mode entry process based on the
configured priorities and reports the outcome.
The mode selection logic attempts to enter prioritized modes sequentially.
A mode is considered successfully negotiated only when its alternate mode
driver explicitly reports a positive status. Alternate mode drivers are
required to report their mode entry status (either successful or failed).
If an alt-mode driver does not report its status within a defined timeout
period, the system automatically proceeds to attempt entry into the next
preferred mode.

This series was tested on a ChromeOS Brya device running kernel 6.6, and on
an Android OS device with kernel 6.12.

Andrei Kuchynski (10):
  usb: typec: Add alt_mode_override field to port property
  platform/chrome: cros_ec_typec: Set alt_mode_override flag
  usb: typec: ucsi: Set alt_mode_override flag
  usb: typec: Expose alternate mode priorities via sysfs
  usb: typec: Implement automated alternate mode selection
  Revert "usb: typec: displayport: Receive DP Status Update NAK request
    exit dp altmode"
  usb: typec: Report altmode entry status via callback
  usb: typec: ucsi: displayport: Propagate DP altmode entry result
  platform/chrome: cros_ec_typec: Propagate altmode entry result
  platform/chrome: cros_ec_typec: Report USB4 mode entry status via
    callback

 Documentation/ABI/testing/sysfs-class-typec  |  34 ++
 drivers/platform/chrome/cros_ec_typec.c      |  11 +
 drivers/platform/chrome/cros_typec_altmode.c |  32 +-
 drivers/platform/chrome/cros_typec_altmode.h |   6 +
 drivers/usb/typec/Makefile                   |   2 +-
 drivers/usb/typec/altmodes/displayport.c     |  17 +-
 drivers/usb/typec/altmodes/thunderbolt.c     |   6 +
 drivers/usb/typec/class.c                    |  95 +++-
 drivers/usb/typec/class.h                    |  16 +
 drivers/usb/typec/mode_selection.c           | 505 +++++++++++++++++++
 drivers/usb/typec/mode_selection.h           |  42 ++
 drivers/usb/typec/ucsi/displayport.c         |   4 +-
 drivers/usb/typec/ucsi/ucsi.c                |   2 +
 include/linux/usb/pd_vdo.h                   |   2 +
 include/linux/usb/typec.h                    |   1 +
 include/linux/usb/typec_altmode.h            |  12 +
 include/linux/usb/typec_dp.h                 |   2 +
 include/linux/usb/typec_tbt.h                |   3 +
 18 files changed, 775 insertions(+), 17 deletions(-)
 create mode 100644 drivers/usb/typec/mode_selection.c
 create mode 100644 drivers/usb/typec/mode_selection.h

-- 
2.50.0.rc1.591.g9c95f17f64-goog