On Tue, Nov 18, 2025 at 04:52:49PM +0200, Tomi Valkeinen wrote: > Hi, > > On 18/11/2025 14:40, Maxime Ripard wrote: > > Hi, > > > > On Tue, Nov 18, 2025 at 05:22:49PM +0530, Harikrishna Shenoy wrote: > >> With the DBANC framework, the connector is no longer initialized in > >> bridge_attach() when the display controller sets the > >> DRM_BRIDGE_ATTACH_NO_CONNECTOR flag. > >> This causes a null pointer dereference in cdns_mhdp_modeset_retry_fn() > >> when trying to access &conn->dev->mode_config.mutex. > >> Observed on a board where EDID read failed. > >> (log: https://gist.github.com/Jayesh2000/233f87f9becdf1e66f1da6fd53f77429) > >> > >> Patch 1 adds a connector_ptr which takes care of both > >> DBANC and !DBANC case by setting the pointer in appropriate hooks > >> and checking for pointer validity before accessing the connector. > >> Patch 2 adds mode validation hook to bridge fucntions. > >> Patch 3 fixes HDCP to work with both DBANC and !DBANC case by > >> moving HDCP state handling into the bridge atomic check in line with > >> the DBANC model. > >> Patches 4,5 do necessary cleanup and alignment for using > >> connector pointer. > > > > It's mentioned several times in your series, and it might be obvious to > > you, but documenting what is the "DBANC framework" is would be helpful. > > I have no idea what it's about, and it appears that Google doesn't know > > either. > Yes, I was a bit baffled initially. DRM_BRIDGE_ATTACH_NO_CONNECTOR.
Oooooh, thanks > I think it makes sense to only use "DBANC" if it's first introduced in > that patch. So don't have a patch that just uses "DBANC", even if the > previous patch did explain what it means. And if there's just one or two > "DBANC"s, just spell it out "DRM_BRIDGE_ATTACH_NO_CONNECTOR". Yeah, I'd go even further. Acronyms are fun but something being obvious is better still. Use the proper flag name every time. Maxime
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