nvidia-modeset: raise default output color depth for HDMI 1.4 Deep Color, EDID VSDB DC_30/DC_36/DC_48 - #1386
Open
danielcamposramos wants to merge 1 commit into
Conversation
NVKMS already parses the sink's HDMI Deep Color capability (VSDB DC_30/DC_36/DC_48) and already constructs and programs 10/12-bpc output for RGB and YCbCr 4:4:4, 4:2:2 and 4:2:0. The only piece keeping a 12-bpc-capable sink at 10 bpc on Linux is this module parameter's default. Windows on the same hardware drives the same sink at 12 bpc. Measured narrowing, GA106 + Sony KDL-46HX855 (EDID declares DC_30/DC_36): Linux 615.71.09 selects 10 bpc where amdgpu on the same sink selects 12 bpc. Refs NVIDIA#1384. The module parameter still permits capping at 10; this only lifts the default so the EDID-declared capability is what decides. Signed-off-by: Daniel Campos Ramos <Capitain_Jack@yahoo.com> Co-Authored-By: Kimi K3 (Claude Code) <noreply@anthropic.com> Co-Authored-By: OpenAI Codex <noreply@openai.com>
|
|
Author
|
The open-source counterpart moved to v2 on the kernel list: https://lore.kernel.org/dri-devel/20260922215317.611388-1-Capitain_Jack@yahoo.com/ It now also has a follow-on series adding limited/full-range RGB and YCbCr 4:4:4, 4:2:2 and 4:2:0 to nouveau: https://lore.kernel.org/dri-devel/20260922215336.612239-1-Capitain_Jack@yahoo.com/ Both were measured on the same GA106 and Sony KDL-46HX855 as this PR, including 3D at 12 bpc. AI partners were leveraged in the production of this work. |
This file contains hidden or bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
Sign up for free
to join this conversation on GitHub.
Already have an account?
Sign in to comment
2 participants
Add this suggestion to a batch that can be applied as a single commit.This suggestion is invalid because no changes were made to the code.Suggestions cannot be applied while the pull request is closed.Suggestions cannot be applied while viewing a subset of changes.Only one suggestion per line can be applied in a batch.Add this suggestion to a batch that can be applied as a single commit.Applying suggestions on deleted lines is not supported.You must change the existing code in this line in order to create a valid suggestion.Outdated suggestions cannot be applied.This suggestion has been applied or marked resolved.Suggestions cannot be applied from pending reviews.Suggestions cannot be applied on multi-line comments.Suggestions cannot be applied while the pull request is queued to merge.Suggestion cannot be applied right now. Please check back later.
What this changes. The
max_output_color_depthmodule parameter's default goes from 10 to 12 on the Linux side.Why it is safe. NVKMS already parses the sink's HDMI Deep Color capability (VSDB
DC_30/DC_36/DC_48) and already constructs and programs 10 and 12 bpc output for RGB and for YCbCr 4:4:4, 4:2:2 and 4:2:0. Nothing new is programmed anywhere; the existing path is simply allowed to reach the depth the sink declares. The parameter still permits capping at 10, so anyone on a marginal link keeps the override.Measured on the current production build. With stock 615.71.09 reloaded using only
nvidia_modeset.max_output_color_depth=12(this change, applied at load time), a GA106 (GALAX RTX 3060) drives a Sony KDL-46HX855 (HDMI 1.4, EDIDDC_30/DC_36, 225 MHz TMDS ceiling) at 1080p60 RGB requiring 222.75 MHz, and the set's own OSD reports 12-bit: passed with full colors (pun intended). Windows on this same card and set already trains 12-bit, and amdgpu on this same sink selects 12 bpc; Linux 615.71.09 at the current default selects 10 bpc on the identical cable. Harness, module-state readback, and the sink observation are preserved: https://github.com/danielcamposramos/sony-bravia-linux/blob/main/tools/stereo-modeset/run24-nvidia-deepcolor-param12-pass-2026-09-22.logRefs #1384 — this addresses the measured deep-colour symptom there (the 10-vs-12 narrowing). It does not touch the mode-prune or 3D-exposure symptoms the same issue tracks.
Open-source counterpart. The same end state for nouveau is in review on the kernel lists as a three-patch HDMI Deep Color series (link-depth selection, GCP state through NVIF, GCP programming around the late HDMI-audio rewrite), hardware-verified at 12 bpc on this same bench: https://lore.kernel.org/dri-devel/20260922192132.114546-1-Capitain_Jack@yahoo.com/
Scope. SDR deep colour only; no HDR claim is made (there is no HDR sink on this bench). Because the parameter gates NVKMS's existing deep-colour selection wholesale, the lifted default applies to its existing YCbCr 4:4:4/4:2:2/4:2:0 modes as well as RGB.
AI partners were leveraged in the production of this work.
🤖 Generated with Claude Code