Re: [PATCH v2 05/12] drm/bridge: synopsys: dw-dp: Add follow-up bridge support

From: Sebastian Reichel <sebastian.reichel@collabora.com>
To: Luca Ceresoli <luca.ceresoli@bootlin.com>
Cc: "Heiko Stübner" <heiko@sntech.de>,
	dri-devel@lists.freedesktop.org, linux-kernel@vger.kernel.org,
	"Laurent Pinchart" <Laurent.pinchart@ideasonboard.com>,
	"Andrzej Hajda" <andrzej.hajda@intel.com>,
	kernel@collabora.com, "David Airlie" <airlied@gmail.com>,
	"Simona Vetter" <simona@ffwll.ch>,
	"Rob Herring" <robh@kernel.org>, "Robert Foss" <rfoss@kernel.org>,
	"Jernej Skrabec" <jernej.skrabec@gmail.com>,
	linux-rockchip@lists.infradead.org, devicetree@vger.kernel.org,
	"Conor Dooley" <conor+dt@kernel.org>,
	"Jonas Karlman" <jonas@kwiboo.se>,
	"Maarten Lankhorst" <maarten.lankhorst@linux.intel.com>,
	"Maxime Ripard" <mripard@kernel.org>,
	"Damon Ding" <damon.ding@rock-chips.com>,
	linux-arm-kernel@lists.infradead.org,
	"Dmitry Baryshkov" <dmitry.baryshkov@oss.qualcomm.com>,
	"Neil Armstrong" <neil.armstrong@linaro.org>,
	"Dmitry Baryshkov" <lumag@kernel.org>,
	"Sandy Huang" <hjc@rock-chips.com>,
	"Alexey Charkov" <alchark@gmail.com>,
	"Thomas Zimmermann" <tzimmermann@suse.de>,
	"Andy Yan" <andy.yan@rock-chips.com>,
	"Krzysztof Kozlowski" <krzk+dt@kernel.org>
Subject: Re: [PATCH v2 05/12] drm/bridge: synopsys: dw-dp: Add follow-up bridge support
Date: Fri, 5 Jun 2026 18:42:06 +0200	[thread overview]
Message-ID: <aiL4lUUa9j6_irAz@venus> (raw)
In-Reply-To: <177918892313.537125.10814687633426590148.b4-review@b4>

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Hello Luca,

On Tue, May 19, 2026 at 01:08:43PM +0200, Luca Ceresoli wrote:
> On Fri, 01 May 2026 00:20:32 +0200, Sebastian Reichel <sebastian.reichel@collabora.com> wrote:
> > diff --git a/drivers/gpu/drm/bridge/synopsys/dw-dp.c b/drivers/gpu/drm/bridge/synopsys/dw-dp.c
> > index fc4ddb7792d7..ccc55e40e81c 100644
> > --- a/drivers/gpu/drm/bridge/synopsys/dw-dp.c
> > +++ b/drivers/gpu/drm/bridge/synopsys/dw-dp.c
> > @@ -2064,6 +2064,20 @@ struct dw_dp *dw_dp_bind(struct device *dev, struct drm_encoder *encoder,
> >  		goto unregister_aux;
> >  	}
> >  
> > +	next_bridge = devm_drm_of_get_bridge(dev, dev->of_node, 1, 0);
> 
> devm_drm_of_get_bridge() looks for either a panel or a bridge. Is it
> possible to have a panel connected here?
> 
> If it isn't, then using of_drm_get_bridge_by_endpoint() which has just been
> merged [0] would be much simpler and cleaner.

Technically this should always be connected to the USBDP PHY
on the Rockchip platforms using this IP (RK3588 & RK3576) and
there are no other upstream platforms using this code so far.

Having said that, we do have some upstream DTs, which directly
connect it to a DP connector instead (as the PHY does not yet
expose a DRM bridge, that's being handled in a different series).
But there is no upstream board connecting it to an eDP panel,
so I will switch over to of_drm_get_bridge_by_endpoint().

Thanks for the info.

Greetings,

-- Sebastian

> 
> [0] https://gitlab.freedesktop.org/drm/misc/kernel/-/commit/03d1078112fddd706b2c1e4a7d98cf18700eb5df
> 
> Luca
> 
> -- 
> Luca Ceresoli, Bootlin
> Embedded Linux and Kernel engineering
> https://bootlin.com
> 

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