drm_dp_tunne...ng_supported(9)

📦 version 7.3.1, in nixpkgs unstable

💅 drm_dp_tunnel_128b132b_lane0_mapping_supported(9) 💅

okay bestie, welcome to the Kernel API Manual — yes that's the manual name, we're in kernel land now, put your hair up 🎀

This one's a little yes/no check about whether lane 0 is mapped the way the DPRX expects on a tunneled 128b/132b link. Very niche, very iconic, let's get into it ✨

🌸 NAME 🌸

drm_dp_tunnel_128b132b_lane0_mapping_supported — literally just checks if 128b/132b lane 0 mapping is supported. that's the whole vibe 💖

✨ SYNOPSIS ✨

bool drm_dp_tunnel_128b132b_lane0_mapping_supported (const struct
drm_dp_tunnel *tunnel );

she takes one arg and hands you back a bool. simple. clean. main character energy 👑

🦋 ARGUMENTS 🦋

  • tunnel — the tunnel object. yes, that's it, that's the whole argument list. go off 💅

💖 DESCRIPTION 💖

so here's the tea 🍓 — this function checks whether the DP-out adapter always maps lane 0 the way the DPRX expects it on a tunneled 128b/132b link.

  • if it returns true, then one- and two-lane configurations with UHBR link rates can always be used. slay, no notes 💀✨
  • if it returns false, using one or two lanes with UHBR link rates may cause a lane-count conversion failure in the DPRX 😭 and that means the source has to take corrective action during link training. not the vibe but okay.

if you want the receipts, see DP Standard v2.1b, section 3.5.2.16.3, 128b/132b DPRX Lane Count Conversion Failure Indication and Corrective Action. iykyk 📖

meanwhile — a four-lane configuration can always be used, as long as the DPRX supports it, no matter what this function returns. so four lanes is the unbothered queen of the situation 👑

and yes, she returns true if the DP-out adapter supports the 128b/132b lane 0 mapping. that's the return value, bestie, that's it 🫶

🌈 SEE ALSO 🌈

the source file, living its best life at:

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

and the whole friend group of related functions, all of them, no gatekeeping 💜

🎀 sign-off 🎀

source of the whole situation: ./drivers/gpu/drm/display — dated October 2026, same title energy as the top, drm_dp_tunne...ng_supported(9) 💫

mwah, go ship that UHBR link, bestie 💅🌸🦋

📦 where this page comes from