On Sat, 31 Aug 2024, Stephen Boyd wrote:

Add a DT graph binding to google,cros-ec-typec so that it can combine
DisplayPort (DP) and USB SuperSpeed (SS) data into a USB type-c endpoint
that is connected to the usb-c-connector node's SS endpoint. This also
allows us to connect the DP and USB nodes in the graph to the USB type-c
connectors, providing the full picture of the USB type-c data flows in
the system.

Allow there to be multiple typec nodes underneath the EC node so that
one DT graph exists per DP bridge. The EC is actually controlling TCPCs
and redrivers that combine the DP and USB signals together so this more
accurately reflects the hardware design without introducing yet another
DT node underneath the EC for USB type-c.

If the type-c ports are being shared between a single DP controller then
the ports need to know about each other and determine a policy to drive
DP to one type-c port. If the type-c ports each have their own dedicated
DP controller then they're able to operate independently and enter/exit
DP altmode independently as well. We can't connect the DP controller's
endpoint to one usb-c-connector port@1 endpoint and the USB controller's
endpoint to another usb-c-connector port@1 endpoint either because the
DP muxing case would have DP connected to two usb-c-connector endpoints
which the graph binding doesn't support.

Therefore, one typec node is required per the capabilities of the type-c
port(s) being managed. This also lets us indicate which type-c ports the
DP controller is wired to. For example, if DP was connected to ports 0
and 2, while port 1 was connected to another DP controller we wouldn't
be able to implement that without having some other DT property to
indicate which output ports are connected to the DP endpoint.

Reviewed-by: Rob Herring (Arm) <robh@kernel.org>
Cc: Krzysztof Kozlowski <redacted>
Cc: Conor Dooley <conor+dt@kernel.org>
Acked-by: Lee Jones <lee@kernel.org>
Cc: Benson Leung <bleung@chromium.org>
Cc: Guenter Roeck <groeck@chromium.org>
Cc: Prashant Malani <redacted>
Cc: Tzung-Bi Shih <tzungbi@kernel.org>
Cc: <redacted>
Cc: <redacted>
Cc: Pin-yen Lin <redacted>
Signed-off-by: Stephen Boyd <redacted>
---
 .../bindings/mfd/google,cros-ec.yaml          |   7 +-

Acked-by: Lee Jones <lee@kernel.org>

 .../bindings/usb/google,cros-ec-typec.yaml    | 229 ++++++++++++++++++
 2 files changed, 233 insertions(+), 3 deletions(-)

-- 
Lee Jones [李琼斯]