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

[Chaoyi Chen]

On 10/24/2025 4:01 PM, Heikki Krogerus wrote:

On Thu, Oct 23, 2025 at 11:30:02AM +0800, Chaoyi Chen wrote:

+static int drm_typec_bus_event(struct notifier_block *nb,
+                              unsigned long action, void *data)
+{
+       struct typec_altmode *alt = (struct typec_altmode *)data;
+
+       if (action != TYPEC_ALTMODE_REGISTERED)
+               goto done;
+
+       if (alt->svid != USB_TYPEC_DP_SID)
+               goto done;
+
+       /*
+        * alt->dev.parent->parent : USB-C controller device
+        * alt->dev.parent         : USB-C connector device
+        */
+       drm_dp_hpd_bridge_register(alt->dev.parent->parent,
+                                  to_of_node(alt->dev.parent->fwnode));

Okay, this explains it. So you do need the port altmode.

So you'll need to export the device types and check that the parent of
the altmode is the port instead of partner.

         if (!is_typec_port(alt->dev.parent) || alt->svid != USB_TYPEC_DP_SID)
                 return NOTIFY_DONE;

I think we might as well export all the types while at it. Check the
attachment.

Oh, I did miss the existence of partner. Thank you for your code!

thanks,

--
Best,
Chaoyi