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

From: Heiko Stuebner <heiko@sntech.de>
To: Andrzej Hajda <andrzej.hajda@intel.com>,
	Neil Armstrong <neil.armstrong@linaro.org>,
	Robert Foss <rfoss@kernel.org>,
	Laurent Pinchart <Laurent.pinchart@ideasonboard.com>,
	Jonas Karlman <jonas@kwiboo.se>,
	Jernej Skrabec <jernej.skrabec@gmail.com>,
	Maarten Lankhorst <maarten.lankhorst@linux.intel.com>,
	Maxime Ripard <mripard@kernel.org>,
	Thomas Zimmermann <tzimmermann@suse.de>,
	David Airlie <airlied@gmail.com>, Simona Vetter <simona@ffwll.ch>,
	Sandy Huang <hjc@rock-chips.com>,
	Andy Yan <andy.yan@rock-chips.com>,
	Cristian Ciocaltea <cristian.ciocaltea@collabora.com>
Cc: kernel@collabora.com, dri-devel@lists.freedesktop.org,
	linux-kernel@vger.kernel.org,
	linux-arm-kernel@lists.infradead.org,
	linux-rockchip@lists.infradead.org,
	Diederik de Haas <diederik@cknow-tech.com>,
	Maud Spierings <maud_spierings@hotmail.com>
Subject: Re: [PATCH v5 05/10] drm/bridge: dw-hdmi-qp: Add HDMI 2.0 SCDC scrambling and high TMDS clock ratio support
Date: Mon, 27 Apr 2026 12:49:09 +0200	[thread overview]
Message-ID: <3826043.PYKUYFuaPT@phil> (raw)
In-Reply-To: <20260426-dw-hdmi-qp-scramb-v5-5-d778e70c317b@collabora.com>

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

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