linux-kernel - Re: [PATCH v3 2/5] drm/bridge: simple: add Realtek RTD2171 DP-to-HDMI bridge

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Message-ID: <u3qwrzwcr4knq7ueinws3siz2frugbkj75r5zp6i7qmkhnyauf@lrmiqhtbgzfj>
Date: Mon, 8 Sep 2025 16:45:23 +0300
From: Dmitry Baryshkov <dmitry.baryshkov@....qualcomm.com>
To: Maud Spierings <maud_spierings@...mail.com>
Cc: neil.armstrong@...aro.org, Laurent.pinchart@...asonboard.com,
        airlied@...il.com, andersson@...nel.org, andrzej.hajda@...el.com,
        conor+dt@...nel.org, devicetree@...r.kernel.org,
        dri-devel@...ts.freedesktop.org, jernej.skrabec@...il.com,
        jonas@...boo.se, kishon@...nel.org, konradybcio@...nel.org,
        krzk+dt@...nel.org, linux-arm-msm@...r.kernel.org,
        linux-kernel@...r.kernel.org, linux-phy@...ts.infradead.org,
        maarten.lankhorst@...ux.intel.com, mripard@...nel.org,
        rfoss@...nel.org, robh@...nel.org, simona@...ll.ch,
        tzimmermann@...e.de, vkoul@...nel.org
Subject: Re: [PATCH v3 2/5] drm/bridge: simple: add Realtek RTD2171
 DP-to-HDMI bridge

On Mon, Sep 08, 2025 at 03:35:23PM +0200, Maud Spierings wrote:
> Hello Neil,
> 
> > Add support for the transparent Realtek RTD2171 DP-to-HDMI bridge.
> > 
> > Reviewed-by: Dmitry Baryshkov <dmitry.baryshkov@....qualcomm.com>
> > Signed-off-by: Neil Armstrong <neil.armstrong@...aro.org>
> > ---
> >  drivers/gpu/drm/bridge/simple-bridge.c | 5 +++++
> >  1 file changed, 5 insertions(+)
> > 
> > diff --git a/drivers/gpu/drm/bridge/simple-bridge.c b/drivers/gpu/drm/bridge/simple-bridge.c
> > index 1f16d568bcc4e0fb56c763244389e6fecbcb2231..e4d0bc2200f8632bcc883102c89c270a17c68d0c 100644
> > --- a/drivers/gpu/drm/bridge/simple-bridge.c
> > +++ b/drivers/gpu/drm/bridge/simple-bridge.c
> > @@ -266,6 +266,11 @@ static const struct of_device_id simple_bridge_match[] = {
> >  		.data = &(const struct simple_bridge_info) {
> >  			.connector_type = DRM_MODE_CONNECTOR_HDMIA,
> >  		},
> > +	}, {
> > +		.compatible = "realtek,rtd2171",
> > +		.data = &(const struct simple_bridge_info) {
> > +			.connector_type = DRM_MODE_CONNECTOR_HDMIA,
> > +		},
> >  	}, {
> >  		.compatible = "ti,opa362",
> >  		.data = &(const struct simple_bridge_info) {
> > 
> > -- 
> > 2.34.1
> 
> I would like to ask again if it may not be a better idea to introduce a
> fallback compatible, once this patchseries lands I will be adding the

I'd say, that's not a good idea. We usually don't have fully datasheets
for those bridges, so we can't be sure that there are no strapping pins
/ other GPIO controls.

> parade,ps185hdm. I don't know how many other variants there are that are
> just simple dp->hdmi bridges that don't require anything other than the
> connector type set to HDMIA. The Thinkbook 16 and zenbook a14 both have HDMI
> connectors, likely with simple bridges too.
> 
> Kind regards,
> Maud

-- 
With best wishes
Dmitry