Re: [PATCH v5 05/10] drm/bridge: dw-hdmi-qp: Add HDMI 2.0 SCDC scrambling and high TMDS clock ratio support

Heiko Stuebner
2026-04-27T10:49:24Z

Am Sonntag, 26. April 2026, 02:20:17 Mitteleuropäische Sommerzeit schrieb Cristian Ciocaltea:
> Enable HDMI 2.0 display modes (e.g. 4K@60Hz) by adding SCDC management
> for the high TMDS clock ratio and scrambling, required when the TMDS
> character rate exceeds the 340 MHz HDMI 1.4b limit.
>
> A periodic work item monitors the sink's scrambling status to recover
> from sink-side resets. On hotplug detect, if SCDC scrambling state is
> out of sync with the driver, trigger a CRTC reset to re-establish the
> link.
>
> Reject modes requiring TMDS rates above 600 MHz, as those fall in the
> HDMI 2.1 FRL domain which is not supported. In no_hpd configurations,
> further restrict to 340 MHz since SCDC requires a connected sink.
>
> Tested-by: Diederik de Haas <diederik@cknow-tech.com>
> Tested-by: Maud Spierings <maud_spierings@hotmail.com>
> Signed-off-by: Cristian Ciocaltea <cristian.ciocaltea@collabora.com>
> ---
> drivers/gpu/drm/bridge/synopsys/dw-hdmi-qp.c | 188 ++++++++++++++++++++++++---
> 1 file changed, 172 insertions(+), 16 deletions(-)
>
> diff --git a/drivers/gpu/drm/bridge/synopsys/dw-hdmi-qp.c b/drivers/gpu/drm/bridge/synopsys/dw-hdmi-qp.c
> index d649a1cf07f5..c482a8e7da25 100644
> --- a/drivers/gpu/drm/bridge/synopsys/dw-hdmi-qp.c
> +++ b/drivers/gpu/drm/bridge/synopsys/dw-hdmi-qp.c
> @@ -2,6 +2,7 @@
> /*
> * Copyright (c) 2021-2022 Rockchip Electronics Co., Ltd.
> * Copyright (c) 2024 Collabora Ltd.
> + * Copyright (c) 2025 Amazon.com, Inc. or its affiliates.

I have no real clue about the inner workings of hdmi, but that line
does make me curious, because no part of the patch authorship does
mention Amazon ;-) .

Also I think "or it's affiliates" might be way too broad, because this
can be essentially everyone. So noone in the future will know who to
ask on copyright questions.

Similarly when _somebody_ comes forward with "I hold a copyright on this"
no-one could verify this claim as well.

I somehow expect _one_ entity being specified, not possibly hundreds.

Heiko