linux-kernel - Re: [PATCH v4 05/10] drm/bridge: dw-hdmi-qp: Set bridge supported

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Message-ID: <3863e0e5-677b-4225-9854-3ee420828275@collabora.com>
Date: Tue, 18 Nov 2025 22:00:08 +0200
From: Cristian Ciocaltea <cristian.ciocaltea@...labora.com>
To: Nicolas Frattaroli <nicolas.frattaroli@...labora.com>,
 Harry Wentland <harry.wentland@....com>, Leo Li <sunpeng.li@....com>,
 Rodrigo Siqueira <siqueira@...lia.com>,
 Alex Deucher <alexander.deucher@....com>,
 Christian König <christian.koenig@....com>,
 David Airlie <airlied@...il.com>, Simona Vetter <simona@...ll.ch>,
 Maarten Lankhorst <maarten.lankhorst@...ux.intel.com>,
 Maxime Ripard <mripard@...nel.org>, Thomas Zimmermann <tzimmermann@...e.de>,
 Andrzej Hajda <andrzej.hajda@...el.com>,
 Neil Armstrong <neil.armstrong@...aro.org>, Robert Foss <rfoss@...nel.org>,
 Laurent Pinchart <Laurent.pinchart@...asonboard.com>,
 Jonas Karlman <jonas@...boo.se>, Jernej Skrabec <jernej.skrabec@...il.com>,
 Sandy Huang <hjc@...k-chips.com>, Heiko Stübner
 <heiko@...ech.de>, Andy Yan <andy.yan@...k-chips.com>,
 Jani Nikula <jani.nikula@...ux.intel.com>,
 Rodrigo Vivi <rodrigo.vivi@...el.com>,
 Joonas Lahtinen <joonas.lahtinen@...ux.intel.com>,
 Tvrtko Ursulin <tursulin@...ulin.net>
Cc: kernel@...labora.com, amd-gfx@...ts.freedesktop.org,
 dri-devel@...ts.freedesktop.org, linux-kernel@...r.kernel.org,
 linux-arm-kernel@...ts.infradead.org, linux-rockchip@...ts.infradead.org,
 intel-gfx@...ts.freedesktop.org, intel-xe@...ts.freedesktop.org
Subject: Re: [PATCH v4 05/10] drm/bridge: dw-hdmi-qp: Set bridge
 supported_formats

Hi Nicolas,

On 11/17/25 9:11 PM, Nicolas Frattaroli wrote:
> The drm_bridge "supported_formats" member stores a bitmask of supported
> HDMI output formats if the bridge is in fact an HDMI bridge.
> 
> However, until now, the synopsys dw-hdmi-qp driver did not set this
> member in the bridge it creates.
> 
> Set it based on the platform data's supported_formats member, and
> default to BIT(HDMI_COLORSPACE_RGB) if it's absent, which preserves the
> previous behaviour.
> 
> Signed-off-by: Nicolas Frattaroli <nicolas.frattaroli@...labora.com>
> ---
>  drivers/gpu/drm/bridge/synopsys/dw-hdmi-qp.c | 5 +++++
>  1 file changed, 5 insertions(+)
> 
> diff --git a/drivers/gpu/drm/bridge/synopsys/dw-hdmi-qp.c b/drivers/gpu/drm/bridge/synopsys/dw-hdmi-qp.c
> index fe4c026280f0..cf888236bd65 100644
> --- a/drivers/gpu/drm/bridge/synopsys/dw-hdmi-qp.c
> +++ b/drivers/gpu/drm/bridge/synopsys/dw-hdmi-qp.c
> @@ -1269,6 +1269,11 @@ struct dw_hdmi_qp *dw_hdmi_qp_bind(struct platform_device *pdev,
>  		dev_warn(dev, "Set ref_clk_rate to vendor default\n");
>  	}
>  
> +	if (plat_data->supported_formats)
> +		hdmi->bridge.supported_formats = plat_data->supported_formats;

This duplicates a change already introduced via commit 1ff27c5929ab
("drm/bridge: dw-hdmi-qp: Handle platform supported formats and color depth").

> +	else
> +		hdmi->bridge.supported_formats = BIT(HDMI_COLORSPACE_RGB);

And this one looks redundant as well, since RGB is supposed to be mandatory:
supported_formats defaults to RGB in drm_bridge_connector_init() if there's no
HDMI bridge in the pipeline overriding it, while drmm_connector_hdmi_init()
errors out if supported_formats is unset or doesn't advertise RGB.

Hence I think this patch can be dropped.

Regards,
Cristian