Re: [PATCH 0/5] usb: typec: cable comms on RT1711H-compatible TCPCs and FUSB302

[Heikki Krogerus]

On Tue, Nov 03, 2026 at 03:21:21PM +0400, Alexey Charkov wrote:
> Neither the RT1711H family (including the HUSB311 and ET7304) nor the
> FUSB302 lets TCPM talk to cable plugs today, so cable discovery is
> skipped, and with it the cable's current and speed ratings.
> 
> The RT1711H family handles SOP' like any other TCPCI-compliant TCPC, but
> enabling it exposed a problem in the TCPCI core: it set SOP' in
> RECEIVE_DETECT whenever the TCPC can talk to cables, regardless of who
> sources VCONN. With the partner as the VCONN Source, the port then acks
> and processes the partner's own traffic with the cable plug.
> 
> Patch 1 fixes a TCPM bug that cable communication on the FUSB302 made
> visible: after a VCONN swap, a source resets the cable plug twice.
> Patch 2 lets a TCPCI TCPC receive SOP' only while it sources VCONN,
> which also affects the Maxim TCPCs, the only ones that enable SOP'
> today. Patch 3 enables SOP' on the RT1711H family. Patches 4 and 5 add
> SOP' to the FUSB302 driver, receiving it under the same VCONN rule.
> 
> Tested on an RK3576 EVB1 (HUSB311, source-only) and Flipper One boards
> (FUSB302B):
> - Without patch 2, a FUSB302 sink sent SOP' Discover Identity over a
>   cable with no e-marker, so the HUSB311 had no VCONN to source. The
>   HUSB311 acked each one and its TCPM answered over SOP, after which the
>   sink soft reset the contract every time.
> - With patch 2, the same messages went unacked and the HUSB311 port
>   correctly ignored them.
> - Over an e-marked 5A EPR cable, the HUSB311 sourced VCONN, read the
>   cable identity and completed discovery, while the FUSB302 sink kept
>   SOP' reception off.
> - With a FUSB302 as source on the same cable, it sourced VCONN, read
>   the cable identity and completed discovery. The cable plug accepted
>   the FUSB302's automatic GoodCRC to its replies, which the datasheet
>   leaves undocumented for SOP'.
> - Between two FUSB302 ports on the same cable, VCONN swaps both ways
>   moved SOP' reception along with VCONN, and each new VCONN Source
>   soft reset the cable plug over SOP'. Without patch 1, the source did
>   so twice.
> 
> Signed-off-by: Alexey Charkov <alchark@xxxxxxxxxxx>

These look okay to me, but let's still wait for Badhri and RD.

Reviewed-by: Heikki Krogerus <heikki.krogerus@xxxxxxxxxxxxxxx>

> ---
> Alexey Charkov (5):
>       usb: typec: tcpm: Stop a source from repeating a cable Soft_Reset
>       usb: typec: tcpci: Receive SOP' only while sourcing VCONN
>       usb: typec: tcpci_rt1711h: Enable SOP' communication
>       usb: typec: fusb302: Tell SOP' messages apart from SOP
>       usb: typec: fusb302: Enable SOP' communication
> 
>  drivers/usb/typec/tcpm/fusb302.c       | 63 ++++++++++++++++++++++++++---
>  drivers/usb/typec/tcpm/fusb302_reg.h   | 10 +++++
>  drivers/usb/typec/tcpm/tcpci.c         | 72 +++++++++++++++++++++++-----------
>  drivers/usb/typec/tcpm/tcpci_rt1711h.c |  1 +
>  drivers/usb/typec/tcpm/tcpm.c          |  2 +
>  5 files changed, 119 insertions(+), 29 deletions(-)
> ---
> base-commit: 2637bdec0535a2044cd830eba9a79363651d9043
> change-id: 20261103-husb311-cable-comm-46f2e77e4c18
> 
> Best regards,
> --  
> Alexey Charkov <alchark@xxxxxxxxxxx>

-- 
heikki