drm_dp_mst_dpcd_write(9)

📦 version 7.3.1, in nixpkgs unstable

💅 drm_dp_mst_dpcd_write — like, the whole vibe (Kernel API Manual, bestie) 🎀

okay so picture this: you're deep in the DRM/KMS mines, you've got an MST topology, and you need to shove some bytes into a remote device's DPCD. Bestie. This is THAT function. It's drm_dp_mst_dpcd_write, and she is the sideband-messaging glow-up of your fave local DPCD writer. Let's get into it ✨

🌸 NAME 🌸

drm_dp_mst_dpcd_write — write a series of bytes to the DPCD via sideband 💫

✨ SYNOPSIS ✨

ssize_t drm_dp_mst_dpcd_write (struct drm_dp_aux *aux , unsigned int
       offset , void *buffer , size_t size );

🦋 ARGUMENTS 🦋

  • aux — the Fake sideband AUX CH 🫶 (yes, "Fake" is doing a lot of work here, and yes, she's iconic for it)
  • offset — address of the (first) register to write — where the bytes are gonna land, bestie 📍
  • buffer — buffer containing the values to write — this is the cargo, the whole payload, the main character of the operation 👑
  • size — number of bytes in buffer — how much of that cargo actually ships 🚚

💖 DESCRIPTION 💖

So here's the tea: this does the same functionality for remote devices via sideband messaging as drm_dp_dpcd_write does for local devices via an actual AUX CH. Not me comparing the two — the manpage literally did it first 😭

Like, same energy, different transport. Remote gets the sideband-messaging route, local gets the real AUX CH route, and both of them are out here writing bytes like the icons they are 💅✨

🔥 RETURN 🔥

  • number of bytes written on success 🎉
  • negative error code on failure 💀
ngl bestie, always check that return value. A negative number is not a cute little vibe, it's something going wrong 🫶

🌈 SEE ALSO 🌈

this list is LONG and we're not skipping a single one of them, okay? every name, exactly as written. no cap. 🍓

Kernel file ./drivers/gpu/drm/display/drm_dp_mst_topology.c

🧚 cute little sign-off 🧚

okay that's the whole page, bestie!! 💜 this one lives in ./drivers/gpu/drm/display, it's tagged October 2026, and it belongs to the Kernel API Manual. go forth and write those sideband bytes responsibly. mwah 💋🦋✨

📦 where this page comes from