raspberrypi
VC4 DPI: When CSYNC is enabled, [NP][HV]SYNC flags are all ignored
Describe the bug
That's not as obviously correct as it looks, since (a poor approximation to) CSYNC can coexist with HSYNC and VSYNC on different pins.
Right now, when CSYNC is enabled it will always be accompanied by positive H and V syncs.
It would be reasonable to allow H and V syncs optionally to be disabled when CSYNC is enabled (for compatibility they should probably not always be disabled), and it seems harmless to allow them optionally to be inverted as well. Therefore, those flags should not be ignored when CSYNC is enabled.
Steps to reproduce the behaviour
It's actually quite awkward as standard overlays, panel timings, kmstest etc don't have a CSYNC option
Device (s)
Raspberry Pi 4 Mod. B
System
rpi-6.12.y and others
Logs
No response
Additional context
No response
OTOH if we did really want to disable H and V syncs when CSYNC was used, we could just add in DPI_HSYNC_DISABLE | DPI_VSYNC_DISABLE in the DRM_MODE_FLAG_CSYNC case.