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

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Message-ID: <34cb0398-a986-48e3-a15b-7bfda6081e21@oss.qualcomm.com>
Date: Mon, 16 Jun 2025 16:34:45 +0300
From: Dmitry Baryshkov <dmitry.baryshkov@....qualcomm.com>
To: Andrei Kuchynski <akuchynski@...omium.org>,
        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
Subject: Re: [PATCH 00/10] USB Type-C mode selection

On 16/06/2025 16:31, Andrei Kuchynski wrote:
> 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.

Both kernels are terribly old. Please run the tests on top of linux-next 
or usb-next.

> 
> 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
> 


-- 
With best wishes
Dmitry