Message-ID: <c9dd365b-ad8f-410e-96f8-f914f03634b2@gmail.com>
Date: Sun, 25 Jan 2026 19:42:16 +0000
From: Hugh Cole-Baker <sigmaris@...il.com>
To: Chaoyi Chen <kernel@...kyi.com>,
 Heikki Krogerus <heikki.krogerus@...ux.intel.com>,
 Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
 Dmitry Baryshkov <dmitry.baryshkov@....qualcomm.com>,
 Peter Chen <hzpeterchen@...il.com>, Luca Ceresoli
 <luca.ceresoli@...tlin.com>, Rob Herring <robh@...nel.org>,
 Krzysztof Kozlowski <krzk+dt@...nel.org>, Conor Dooley
 <conor+dt@...nel.org>, Vinod Koul <vkoul@...nel.org>,
 Kishon Vijay Abraham I <kishon@...nel.org>, Heiko Stuebner
 <heiko@...ech.de>, Sandy Huang <hjc@...k-chips.com>,
 Andy Yan <andy.yan@...k-chips.com>,
 Yubing Zhang <yubing.zhang@...k-chips.com>,
 Frank Wang <frank.wang@...k-chips.com>,
 Andrzej Hajda <andrzej.hajda@...el.com>,
 Neil Armstrong <neil.armstrong@...aro.org>, Robert Foss <rfoss@...nel.org>,
 Laurent Pinchart <Laurent.pinchart@...asonboard.com>,
 Jonas Karlman <jonas@...boo.se>, Jernej Skrabec <jernej.skrabec@...il.com>,
 Maarten Lankhorst <maarten.lankhorst@...ux.intel.com>,
 Maxime Ripard <mripard@...nel.org>, Thomas Zimmermann <tzimmermann@...e.de>,
 David Airlie <airlied@...il.com>, Simona Vetter <simona@...ll.ch>,
 Amit Sunil Dhamne <amitsd@...gle.com>,
 Chaoyi Chen <chaoyi.chen@...k-chips.com>, Dragan Simic <dsimic@...jaro.org>,
 Johan Jonker <jbx6244@...il.com>, Diederik de Haas <didi.debian@...ow.org>,
 Peter Robinson <pbrobinson@...il.com>
Cc: linux-usb@...r.kernel.org, devicetree@...r.kernel.org,
 linux-kernel@...r.kernel.org, linux-phy@...ts.infradead.org,
 linux-arm-kernel@...ts.infradead.org, linux-rockchip@...ts.infradead.org,
 dri-devel@...ts.freedesktop.org
Subject: Re: [PATCH v14 0/9] Add Type-C DP support for RK3399 EVB IND board

On 19/01/2026 07:30, Chaoyi Chen wrote:
> From: Chaoyi Chen <chaoyi.chen@...k-chips.com>
> 
> This series focuses on adding Type-C DP support for USBDP PHY and DP
> driver. The USBDP PHY and DP will perceive the changes in cable status
> based on the USB PD and Type-C state machines provided by TCPM. Before
> this, the USBDP PHY and DP controller of RK3399 sensed cable state
> changes through extcon, and devices such as the RK3399 Gru-Chromebook
> rely on them. This series should not break them.
> 
> ====
> 1. DisplayPort HPD status notify
> 
> Before v7, I implemented a variety of DP HPD status notify. However,
> they all had various problems and it was difficult to become a generic
> solution.
> 
> Under the guidance of Heikki and Dmitry, a decoupled notification
> method between the TypeC and DRM subsystems was introduced in v7.
> First, a notification is sent when TypeC registers a new altmode.
> Then, a generic DP AUX HPD bridge is implemented on the DRM side.
> 
> During v7-v10, we added a new notifier in typec to notify the altmode
> device register event. With the help of Greg and Heikki, we implemented
> the reuse of notifiers for the type bus itself in patch1 of v11.
> 
> The USB subsystem related parts have already been merged into the
> usb-next branch in v13 [0][1]. Therefore, this series no longer includes
> these patches starting from v14. Thanks to Greg and Heikki!
> 
> [0]: https://git.kernel.org/pub/scm/linux/kernel/git/gregkh/usb.git/commit/?h=usb-next&id=67ab45426215c7fdccb65aecd4cac15bbe4dfcbb
> [1]: https://git.kernel.org/pub/scm/linux/kernel/git/gregkh/usb.git/commit/?h=usb-next&id=4dee13db29de6dd869af9b3827e1ff569644e838
> 
> That makes it redundant for each Type-C controller driver to implement
> a similar DP AUX HPD bridge in embedded scenarios.
> 
> ====
> 2. Altmode switching and orientation switching for USBDP PHY
> 
> For USB Type-C interfaces, an external Type-C controller chip assists
> by detecting cable attachment, determining plug orientation, and
> reporting USB PD message. The USB/DP combo PHY supports software
> configurable pin mapping and DisplayPort lane assignment. Based on
> these message, the combo PHY can perform both altmode switching and
> orientation switching via software.
> 
> The RK3399 EVB IND board has a Type-C interface DisplayPort. It use
> fusb302 chip as Type-C controller. The connection diagram is shown below:
> 
> fusb302 chip +---> USB2.0 PHY ----> DWC3 USB controller
>              |
>              +---> USB/DP PHY0 +--> CDN-DP controller
>                                |
>                                +--> DWC3 USB controller
> 
> ====
> 3. Multiple bridge model for RK3399 CDN-DP
> 
> The RK3399 has two USB/DP combo PHY and one CDN-DP controller. And
> the CDN-DP can be switched to output to one of the PHYs.
> 
> USB/DP PHY0 ---+
>                | <----> CDN-DP controller
> USB/DP PHY1 ---+
> 
> In previous versions, if both PHY ports were connected to DP,
> the CDN-DP driver would select the first PHY port for output.
> 
> On Dmitry's suggestion, we introduced a multi-bridge model to support
> flexible selection of the output PHY port. For each PHY port, a
> separate encoder and bridge are registered.
> 
> The change is based on the DRM AUX HPD bridge, rather than the
> extcon approach. This requires the DT to correctly describe the
> connections between the first bridge in bridge chain and DP
> controller. And Once the first bridge is obtained, we can get the
> last bridge corresponding to the USB-C connector, and then set the
> DRM connector's fwnode to the corresponding one to enable HPD
> notification.

With a similar dts patch [1] on top of this series I tested a type-C to
DP adapter/cable for display output on the ROCKPro64 board, which also
pairs a FUSB302 with RK3399. Booting it up with the cable plugged in
works, as does hotplugging the cable after booting in both orientations.
The correct mode for the display is detected. I wasn't able to test
audio, only video output, as this display doesn't have speakers.

I did once, after unplugging and reconnecting the cable a few times,
see it get into a state where it didn't detect the attached display.
Logs from that unplug/reconnect attempt are here [2] if of interest.
Nevertheless, hotplug seems to work the majority of the time, so

Tested-by: Hugh Cole-Baker <sigmaris@...il.com>

[1]: https://github.com/sigmaris/linux/commit/91724088b19bee7d248946442a801423e8cd0634
[2]: https://gist.github.com/sigmaris/fa107384a7492583ceee1c2962f5030a

> ====
> Patch1 add generic USB Type-C DP HPD bridge (Dmitry, Heikki).
> Patch2 add new API drm_aux_bridge_register_from_node() (Neil).
> Patch3 add new Type-C mode switch for RK3399 USBDP phy binding (Krzysztof).
> Patch4 add typec_mux and typec_switch for RK3399 USBDP PHY.
> Patch5 add DRM AUX bridge support for RK3399 USBDP PHY (Neil).
> Patch6 drops CDN-DP's extcon dependency when Type-C is present (Dmitry).
> Patch7 add multiple bridges to support PHY port selection (Dmitry, Luca).
> Patch8 add missing dp_out port for RK3399 CDN-DP.
> Patch9 add Type-C DP support for RK3399 EVB IND board (Diederik, Peter).
> 
> Changes in v14:
> - Link to V13: https://lore.kernel.org/all/20251208015500.94-1-kernel@airkyi.com/
> - Drop the patches for the USB Type-C subsusytem part, as they have
>   already been merged into usb-next.
> 
> Changes in v13:
> - Link to V12: https://lore.kernel.org/all/20251204063109.104-1-kernel@airkyi.com/
> - Only register drm dp hpd bridge for typec port altmode device.
> 
> Changes in v12:
> - Link to V11: https://lore.kernel.org/all/20251128020405.90-1-kernel@airkyi.com/
> - Add missing Signed-off-by line.
> 
> Changes in v11:
> - Link to V10: https://lore.kernel.org/all/20251120022343.250-1-kernel@airkyi.com/
> - Switch to using typec bus notifiers.
> 
> Changes in v10:
> - Link to V9: https://lore.kernel.org/all/20251111105040.94-1-kernel@airkyi.com/
> - Notify TYPEC_ALTMODE_UNREGISTERED when altmode removed. 
> - Add drm_aux_bridge_register_from_node().
> - Fix refcount usage of drm_bridge.
> 
> Changes in v9:
> - Link to V8: https://lore.kernel.org/all/20251029071435.88-1-kernel@airkyi.com/
> - Remove the exposed DRM_AUX_HPD_BRIDGE option, and select
> DRM_AUX_HPD_TYPEC_BRIDGE when it is available.
> - Add usb role switch for Type-C.
> - Remove USB2 PHY in Type-C connection.
> - ...
> 
> Changes in v8:
> - Link to V7: https://lore.kernel.org/all/20251023033009.90-1-kernel@airkyi.com/
> - Export all typec device types for identification.
> - Merge generic DP HPD bridge into one module.
> - Fix coding style.
> 
> Changes in v7:
> - Link to V6: https://lore.kernel.org/all/20251016022741.91-1-kernel@airkyi.com/
> - Add notifier functions for Type-C core.
> - Add generic USB Type-C DP HPD bridge.
> 
> Changes in v6:
> - Link to V5: https://lore.kernel.org/all/20251011033233.97-1-kernel@airkyi.com/
> - Fix depend in Kconfig.
> - Check DP svid in tcphy_typec_mux_set().
> - Remove mode setting in tcphy_orien_sw_set().
> - Rename some variable names.
> - Attach the DP bridge to the next bridge.
> 
> Changes in v5:
> - Link to V4: https://lore.kernel.org/all/20250922012039.323-1-kernel@airkyi.com/
> - Remove the calls related to `drm_aux_hpd_bridge_notify()`.
> - Place the helper functions in the same compilation unit.
> - Add more comments about parent device.
> - Add DRM AUX bridge support for RK3399 USBDP PHY
> - By parsing the HPD bridge chain, set the connector's of_node to the
> of_node corresponding to the USB-C connector.
> - Return EDID cache when other port is already enabled.
> 
> Changes in v4:
> - Link to V3: https://lore.kernel.org/all/20250729090032.97-1-kernel@airkyi.com/
> - Add default HPD device for DisplayPort altmode.
> - Introduce multiple bridges for CDN-DP.
> - ...
> 
> Changes in v3:
> - Link to V2: https://lore.kernel.org/all/20250718062619.99-1-kernel@airkyi.com/
> - Add more descriptions to clarify the role of the PHY in switching.
> - Fix wrong vdo value.
> - Fix port node in usb-c-connector.
> 
> Changes in v2:
> - Link to V1: https://lore.kernel.org/all/20250715112456.101-1-kernel@airkyi.com/
> - Reuse dp-port/usb3-port in rk3399-typec-phy binding.
> - Fix compile error when CONFIG_TYPEC is not enabled.
> - Notify DP HPD state by USB/DP PHY.
> - Ignore duplicate HPD events.
> - Add endpoint to link DP PHY and DP controller.
> - Fix devicetree coding style.
> 
> Chaoyi Chen (9):
>   drm/bridge: Implement generic USB Type-C DP HPD bridge
>   drm/bridge: aux: Add drm_aux_bridge_register_from_node()
>   dt-bindings: phy: rockchip: rk3399-typec-phy: Support mode-switch
>   phy: rockchip: phy-rockchip-typec: Add typec_mux/typec_switch support
>   phy: rockchip: phy-rockchip-typec: Add DRM AUX bridge
>   drm/rockchip: cdn-dp: Support handle lane info without extcon
>   drm/rockchip: cdn-dp: Add multiple bridges to support PHY port
>     selection
>   arm64: dts: rockchip: Add missing dp_out port for RK3399 CDN-DP
>   arm64: dts: rockchip: rk3399-evb-ind: Add support for DisplayPort
> 
>  .../phy/rockchip,rk3399-typec-phy.yaml        |   6 +
>  arch/arm64/boot/dts/rockchip/rk3399-base.dtsi |  10 +-
>  .../boot/dts/rockchip/rk3399-evb-ind.dts      | 147 +++++++
>  drivers/gpu/drm/bridge/Kconfig                |  10 +
>  drivers/gpu/drm/bridge/Makefile               |   1 +
>  drivers/gpu/drm/bridge/aux-bridge.c           |  24 +-
>  .../gpu/drm/bridge/aux-hpd-typec-dp-bridge.c  |  49 +++
>  drivers/gpu/drm/rockchip/Kconfig              |   1 +
>  drivers/gpu/drm/rockchip/cdn-dp-core.c        | 350 +++++++++++++---
>  drivers/gpu/drm/rockchip/cdn-dp-core.h        |  18 +-
>  drivers/phy/rockchip/Kconfig                  |   3 +
>  drivers/phy/rockchip/phy-rockchip-typec.c     | 373 +++++++++++++++++-
>  include/drm/bridge/aux-bridge.h               |   6 +
>  13 files changed, 914 insertions(+), 84 deletions(-)
>  create mode 100644 drivers/gpu/drm/bridge/aux-hpd-typec-dp-bridge.c
> 

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