Interfacing (DSI, CSI, I2C, etc.) • Re: Horizontal Pixel Repetition via HDMI

The HDMI mandated pixel doubling in order to avoid dropping the clock too low for some modes is implemented within the DRM/KMS framework via the DRM_MODE_FLAG_DBLCLK flag (https://github.com/raspberrypi/linux/bl ... mode.h#L83).
A 320x240 mode with that flag set should produce 640 pixels per line on the wire. This should apply for any Linux system using DRM/KMS drivers, not just on the Pi.

You'll find the flag set in the CEA defined modes that require it, eg modes 6-9 https://github.com/raspberrypi/linux/bl ... #L749-L799

Statistics: Posted by 6by9 — Sat Oct 18, 2025 7:28 pm

---