drm/display: hdmi: Add HDMI 2.0 scrambling management helpers

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Add helpers to manage the full lifecycle of HDMI 2.0 SCDC scrambling on
both source and sink sides:

- drm_hdmi_mode_needs_scrambling(): checks whether a mode, bits per
  component and output format combination requires scrambling, which is
  needed when the resulting TMDS character rate exceeds the HDMI 1.3
  maximum of 340 MHz

- drm_connector_hdmi_enable_scrambling(): configures SCDC scrambling and
  high TMDS clock ratio and starts a periodic work item that monitors
  the sink's SCDC scrambling status, retrying setup when the sink loses
  state

- drm_connector_hdmi_disable_scrambling(): tears down scrambling on both
  sides and cancels the monitoring work

- drm_connector_hdmi_sync_scdc(): triggers a CRTC reset on reconnection
  to restore SCDC state lost during sink disconnects within an active
  display pipeline

Tested-by: Maud Spierings <maud_spierings@hotmail.com>
Tested-by: Diederik de Haas <diederik@cknow-tech.com>  # NanoPC-T6 LTS, Rock 5B
Reviewed-by: Maxime Ripard <mripard@kernel.org>
Tested-by: Igor Paunovic <royalnet026@gmail.com> # RK3588 Orange Pi 5 Plus, dual HDMI
Tested-by: Robin Räber <robin.raebi@gmail.com>
Link: https://patch.msgid.link/20260901-dw-hdmi-qp-scramb-v11-10-bc12954a0688@collabora.com
Signed-off-by: Cristian Ciocaltea <cristian.ciocaltea@collabora.com>

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This commit is contained in:

Cristian Ciocaltea 2026-09-01 21:50:34 +03:00

parent f57c219838

commit d653818324

2 changed files with 312 additions and 0 deletions

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297

drivers/gpu/drm/display/drm_hdmi_helper.c

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15

include/drm/display/drm_hdmi_helper.h

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