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

[Dmitry Baryshkov]

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