Hi all, On 12/7/21 13:26, Heikki Krogerus wrote: > +Hans and Imre > > On Mon, Dec 06, 2021 at 02:31:40PM -0800, Bjorn Andersson wrote: >> On Thu 07 Oct 03:17 PDT 2021, Heikki Krogerus wrote: >>> On Wed, Oct 06, 2021 at 01:26:35PM -0700, Prashant Malani wrote: >>>> (CC+ Heikki) >> [..] >>>> On Wed, Oct 6, 2021 at 8:19 AM Doug Anderson <dianders@xxxxxxxxxxxx> wrote: >> [..] >>> void drm_connector_oob_hotplug_event(struct fwnode_handle *connector_fwnode); >>> >>> If your USB Type-C controller/port driver does not yet register the DP >>> alt mode, the it's responsible of handling HPD separately by calling >>> drm_connector_oob_hotplug_event() on its own. >>> >> >> Finally found my way back to this topic and it doesn't look like I can >> reuse the existing altmode code with the firmware interface provided by >> Qualcomm, so I just hacked something up that invokes >> drm_connector_oob_hotplug_event(). >> >> But I'm not able to make sense of what the expected usage is. Reading >> altmode/displayport.c, it seems that I should only invoke >> drm_connector_oob_hotplug_event() as HPD state toggles. >> >> I made a trial implementation of this, where my firmware interface >> driver calls drm_connector_oob_hotplug_event() every time HPD state >> changes and then in my oob_hotplug_event callback I flip the DP >> controller between on and off. >> >> Unfortunately when I then connect my HDMI dongle, I get HPD state HIGH, >> call the oob_hotplug_event, the DP driver powers up and concludes that >> there's nothing connected to the dongle and goes to idle. I then connect >> the HDMI cable to the dongle, the firmware sends me another message with >> HPD irq and state HIGH, which I ignore because it's not a change in >> state. >> >> In the end I hacked up drm_connector_oob_hotplug_event() to allow me to >> pass the HPD state and this solves my problem. I can now distinguish >> between connect, disconnect and attention. >> >> Can you please help shed some light on what I might be missing? The plan always was to pass some extra information, like the number of available DP lanes (which can make training faster) along as parameter to the drm_connector_oob_hotplug_event(). The merged version ended up not doing this because there were no consumers, but passing additional info like HPD state definitely is ok. Regards, Hans i
