Re: [PATCH v8 03/10] drm/bridge: Implement generic USB Type-C DP HPD bridge

[Chaoyi Chen]

On 11/3/2025 12:00 PM, Dmitry Baryshkov wrote:

> On Wed, Oct 29, 2025 at 03:14:28PM +0800, Chaoyi Chen wrote:
> > From: Chaoyi Chen <chaoyi.chen@xxxxxxxxxxxxxx>
> >
> > 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.
> This doesn't describe the problem that you are trying to solve.
>
> > Signed-off-by: Chaoyi Chen <chaoyi.chen@xxxxxxxxxxxxxx>
> > ---
> >
> > Changes in v8:
> > - Merge generic DP HPD bridge into one module.
> >
> >   drivers/gpu/drm/bridge/Kconfig                |  5 +-
> >   drivers/gpu/drm/bridge/Makefile               |  8 +++-
> >   drivers/gpu/drm/bridge/aux-hpd-bridge.c       | 23 ++++++++-
> >   drivers/gpu/drm/bridge/aux-hpd-bridge.h       | 13 +++++
> >   .../gpu/drm/bridge/aux-hpd-typec-dp-bridge.c  | 47 +++++++++++++++++++
> >   5 files changed, 93 insertions(+), 3 deletions(-)
> >   create mode 100644 drivers/gpu/drm/bridge/aux-hpd-bridge.h
> >   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 a250afd8d662..17257b223a28 100644
> > --- a/drivers/gpu/drm/bridge/Kconfig
> > +++ b/drivers/gpu/drm/bridge/Kconfig
> > @@ -23,13 +23,16 @@ config DRM_AUX_BRIDGE
> >   	  build bridges chain.
> >   
> >   config DRM_AUX_HPD_BRIDGE
> > -	tristate
> > +	tristate "AUX HPD bridge support"
> Why? No, this is supposed to be selected by other drivers. Users don't
> know an wouldn't know what is this.
Sorry, I might have misunderstood you point. In v7, I added a new DRM_AUX_TYPEC_DP_HPD_BRIDGE module to select DRM_AUX_HPD_BRIDGE. This seems to fit the "selected by other drivers" scenario, but I think you might not want to expose any information to the users.

And the other one is what Heikki said:

+if DRM_AUX_HPD_BRIDGE + +config DRM_AUX_HPD_TYPEC_BRIDGE + tristate + depends on TYPEC || !TYPEC + default TYPEC + +endif /* DRM_AUX_HPD_BRIDGE */ + menu "Display Interface Bridges" depends on DRM && DRM_BRIDGE

If I understand correctly, in this scenario we need to select DRM_AUX_HPD_BRIDGE in the DP driver. When Type-C is available, DRM_AUX_HPD_TYPEC_BRIDGE will be selected automatically.

Is the method mentioned by Heikki what you want? Thank you.

--
Best,
Chaoyi