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

Sebastian Reichel <[email protected]> Tue, 28 Jul 2026 12:44:23 +0200

Newsgroups	org.infradead.lists.linux-rockchip,org.freedesktop.lists.dri-devel,org.infradead.lists.linux-arm-kernel,org.infradead.lists.linux-phy,org.kernel.vger.linux-kernel
Message-ID	<amh1sK_4KnD5zTlZ@venus>

Hello Chaoyi,

On Tue, Jul 28, 2026 at 10:33:48AM +0800, Chaoyi Chen wrote:
> >> Changes in v4:
> >> - Link to v3: https://lore.kernel.org/all/[email protected]/
> >> - 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.

Add what exactly? As this code is quite generic, you don't have
anything for a MODULE_DEVICE_TABLE() (i.e. no OF, no I2C, ...).

One solution I see to keep the notifier design would be to add

MODULE_SOFTDEP("pre: aux-hpd-typec-dp-bridge")

to some other module and piggy-back on it. Alternatively integrate
it directly to some other module, such as "drm_display_helper",
which already has DRM_DISPLAY_DP_HELPER and DRM_DISPLAY_DP_TUNNEL.
Adding TypeC DP AltMode as part of it seems sensible to me.

FWIW I suggest you test booting your patches work with the arm64
defconfig before your next submission ;)

Greetings,

-- Sebastian

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