Hi, On Mon, May 26, 2025 at 1:41 AM Ernest Van Hoecke <ernestvanhoe...@gmail.com> wrote: > > Hi Jayesh, > > First of all, thanks for your patch. I applied it to our 6.6-based > downstream kernel supporting a board I have here, and noticed some > strange behaviour with eDP now. > > On Thu, May 08, 2025 at 05:24:33PM +0530, Jayesh Choudhary wrote: > > + if (pdata->bridge.type == DRM_MODE_CONNECTOR_eDP) > > + regmap_update_bits(pdata->regmap, SN_HPD_DISABLE_REG, > > HPD_DISABLE, > > + HPD_DISABLE); > > > > On my setup it seems that `pdata->bridge.type` is not yet set here, > because it executes before `ti_sn_bridge_probe`. For the DP use case, > this is not a problem because the type field is 0 (i.e., not > DRM_MODE_CONNECTOR_eDP) in that case. But for eDP, it means that we are > unexpectedly not disabling HDP. > > With working HDP, everything is fine in the end for both DP and eDP. But > when the HDP line is not connected, eDP no longer works. So I wonder if > this breaks some functionality for weird eDP panels or board > implementations. > > I could certainly be missing something; from my understanding it looks > like without a good HPD signal, the `ti_sn_bridge_probe` and quoted code > are stuck in a loop. `ti_sn65dsi86_enable_comms` runs but does not > disable HDP, after which the probe runs but fails and does not set the > type field, so the next `enable_comms` run fails to disable HDP again, > etc.
This does sound like a real problem. I'm not sure I'll have the time to analyze it and come up with a proposal myself right now, but Jayesh: you should make sure you consider and address this issue before you send your next version. Thanks!
