Re: [PATCH v4 0/5] This series is split from the v15 "Add Type-C DP support for RK3399 EVB

[Chaoyi Chen <chaoyi.chen@rock-chips.com>]

Hi Sebastian,

On 7/28/2026 10:08 AM, Sebastian Reichel wrote:
> Hello Chaoyi,
> 
> On Mon, Jul 27, 2026 at 02:44:03PM +0800, Chaoyi Chen wrote:
>> From: Chaoyi Chen <chaoyi.chen@rock-chips.com>
>>
>> [1] https://lore.kernel.org/all/20260304094152.92-1-kernel@airkyi.com/
>>
>> ====
>> 1. Generic Type-C DP HPD bridge
>>
>> Currently, several USB-C controller drivers register their own DP HPD
>> bridge via aux-hpd-bridge.c, each duplicating the same logic. For
>> devicetree based platforms, the USB-C controller may vary across boards,
>> and not every USB-C controller driver implements this feature. Patch 1
>> implements a generic DP HPD bridge that monitors Type-C bus events and
>> automatically creates an HPD bridge when a Type-C port device with DP
>> SVID is registered.
>>
>> 2. Multiple bridge model for CDN-DP
>>
>> The RK3399 has two USB/DP combo PHY and one CDN-DP controller. Patch 5
>> introduces a multi-bridge model where each PHY port gets a separate
>> encoder and bridge, allowing flexible selection of the output PHY port.
>> This is based on the DRM AUX HPD bridge rather than extcon.
>>
>> ====
>> Patch 1 adds generic USB Type-C DP HPD bridge (Dmitry, Heikki).
>> Patch 2 adds new API drm_aux_bridge_register_from_node() (Neil).
>> Patch 3 adds DRM AUX bridge support for RK3399 USBDP PHY (Neil).
>> Patch 4 drops CDN-DP's extcon dependency when Type-C is present (Dmitry).
>> Patch 5 adds multiple bridges to support PHY port selection (Dmitry, Luca).
>>
>> Changes in v4:
>> - Link to v3: https://lore.kernel.org/all/20260717072323.96-1-kernel@airkyi.com/
>> - Scan the entire typec_bus and attempt to register the hpd bridge,
>>   so as not to miss devices that were already added during initialization.
> 
> While that may help with the module being loaded late, it does not
> help with triggering the module load in the first place.
> 
> The module does not have any MODULE_DEVICE_TABLE() helping with
> that. So basically any system relying on the automatic hpd bridge
> registration and using a modular kernel (e.g. the arm64 defconfig or
> the kernels usually provided by Linux distributions) requires
> manually loading that module to get any graphical output.
>

Thank you for pointing this out. I will add it in v5.

> Greetings,
> 
> -- Sebastian
> 
>> Changes in v3:
>> - Link to v2: https://lore.kernel.org/all/20260608070805.88-1-kernel@airkyi.com/
>>   (Sorry, I forgot to add the "v2" title, so it looks like v1.)
>> - Remove now-redundant call to drm_connector_attach_encoder()
>> - Rebase to v7.2-rc2
>>
>> Changes in v2:
>> - Link to v1: https://lore.kernel.org/all/20260521032854.103-1-kernel@airkyi.com/
>> - Add copyright text.
>> - Remove useless goto.
>> - Fix incorrect function names in the documentation comments.
>> - Fix the check logic for dp->active_port (0 is valid).
>> - Fix the uninitialized prev_port.
>> - Remove duplicate logic from cdn_dp_switch_port().
>> - Fix the prototype of cdn_dp_bridge_hpd_notify().
>> - Properly release connector->fwnode.
>> - Properly release next_bridge.
>>
>> Chaoyi Chen (5):
>>   drm/bridge: Implement generic USB Type-C DP HPD bridge
>>   drm/bridge: aux: Add drm_aux_bridge_register_from_node()
>>   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
>>
>>  drivers/gpu/drm/bridge/Kconfig                |  10 +
>>  drivers/gpu/drm/bridge/Makefile               |   1 +
>>  drivers/gpu/drm/bridge/aux-bridge.c           |  26 +-
>>  .../gpu/drm/bridge/aux-hpd-typec-dp-bridge.c  |  64 ++++
>>  drivers/gpu/drm/rockchip/Kconfig              |   1 +
>>  drivers/gpu/drm/rockchip/cdn-dp-core.c        | 358 ++++++++++++++----
>>  drivers/gpu/drm/rockchip/cdn-dp-core.h        |  18 +-
>>  drivers/phy/rockchip/Kconfig                  |   2 +
>>  drivers/phy/rockchip/phy-rockchip-typec.c     |  13 +-
>>  include/drm/bridge/aux-bridge.h               |   6 +
>>  10 files changed, 428 insertions(+), 71 deletions(-)
>>  create mode 100644 drivers/gpu/drm/bridge/aux-hpd-typec-dp-bridge.c
>>
>> -- 
>> 2.53.0
>>
>>

-- 
Best, 
Chaoyi