[PATCH v7 2/9] drm/bridge: Implement generic USB Type-C DP HPD bridge

[Chaoyi Chen]

Hi Heikki,

On 10/23/2025 4:45 PM, Heikki Krogerus wrote:
> On Thu, Oct 23, 2025 at 11:30:02AM +0800, Chaoyi Chen wrote:
>> From: Chaoyi Chen <chaoyi.chen at rock-chips.com>
>>
>> Several USB-C controller drivers have already implemented the DP HPD
>> bridge function provided by aux-hpd-bridge.c, but there are still
>> some USB-C controller driver that have not yet implemented it.
>>
>> This patch implements a generic DP HPD bridge based on aux-hpd-bridge.c,
>> so that other USB-C controller drivers don't need to implement it again.
>>
>> Signed-off-by: Chaoyi Chen <chaoyi.chen at rock-chips.com>
>> ---
>>   drivers/gpu/drm/bridge/Kconfig                | 11 ++++
>>   drivers/gpu/drm/bridge/Makefile               |  1 +
>>   .../gpu/drm/bridge/aux-hpd-typec-dp-bridge.c  | 51 +++++++++++++++++++
>>   3 files changed, 63 insertions(+)
>>   create mode 100644 drivers/gpu/drm/bridge/aux-hpd-typec-dp-bridge.c
>>
>> diff --git a/drivers/gpu/drm/bridge/Kconfig b/drivers/gpu/drm/bridge/Kconfig
>> index b9e0ca85226a..9f31540d3ad8 100644
>> --- a/drivers/gpu/drm/bridge/Kconfig
>> +++ b/drivers/gpu/drm/bridge/Kconfig
>> @@ -33,6 +33,17 @@ config DRM_AUX_HPD_BRIDGE
>>   menu "Display Interface Bridges"
>>   	depends on DRM && DRM_BRIDGE
>>   
>> +config DRM_AUX_TYPEC_DP_HPD_BRIDGE
>> +	tristate "TypeC DP HPD bridge"
>> +	depends on DRM_BRIDGE && OF && TYPEC
>> +	select DRM_AUX_HPD_BRIDGE
>> +	help
>> +	  Simple USB Type-C DP bridge that terminates the bridge chain and
>> +	  provides HPD support.
>> +
>> +	  If the USB-C controller driver has not implemented this and you need
>> +	  the DP HPD support, say "Y" or "m" here.
> You don't need to depend on DRM_BRIDGE separately, but do you really
> need a separate module for this in the first place?
>
>>   config DRM_CHIPONE_ICN6211
>>   	tristate "Chipone ICN6211 MIPI-DSI/RGB Converter bridge"
>>   	depends on OF
>> diff --git a/drivers/gpu/drm/bridge/Makefile b/drivers/gpu/drm/bridge/Makefile
>> index 245e8a27e3fc..e91736829167 100644
>> --- a/drivers/gpu/drm/bridge/Makefile
>> +++ b/drivers/gpu/drm/bridge/Makefile
>> @@ -1,6 +1,7 @@
>>   # SPDX-License-Identifier: GPL-2.0
>>   obj-$(CONFIG_DRM_AUX_BRIDGE) += aux-bridge.o
>>   obj-$(CONFIG_DRM_AUX_HPD_BRIDGE) += aux-hpd-bridge.o
>> +obj-$(CONFIG_DRM_AUX_TYPEC_DP_HPD_BRIDGE) += aux-hpd-typec-dp-bridge.o
> Instead, why not just make that a part of aux-hpd-bridge
> conditionally:
>
> ifneq ($(CONFIG_TYPEC),)
>          aux-hpd-bridge-y        += aux-hpd-typec-dp-bridge.o
> endif

Oh, I did consider that! But I noticed that aux-hpd-bridge.c contains the following statement module_auxiliary_driver(drm_aux_hpd_bridge_drv), which already includes a module_init. In the newly added file, in order to call the register function, another module_init was also added. If the two files are each made into a module separately, would there be a problem?


>
>
> thanks,
>
-- 
Best,
Chaoyi