linux-kernel - Re: [PATCH v3 08/10] drm/display: bridge-connector: handle CEC adapters

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Message-ID: <qe7cm52nozxvawm6yjzbvfarwoiokpwkr26s66tkypgrsztc7t@vnzbek6i4qhr>
Date: Wed, 29 Jan 2025 01:44:09 +0200
From: Dmitry Baryshkov <dmitry.baryshkov@...aro.org>
To: Maxime Ripard <mripard@...nel.org>
Cc: Maarten Lankhorst <maarten.lankhorst@...ux.intel.com>, 
	Thomas Zimmermann <tzimmermann@...e.de>, David Airlie <airlied@...il.com>, 
	Simona Vetter <simona@...ll.ch>, Dave Stevenson <dave.stevenson@...pberrypi.com>, 
	Maíra Canal <mcanal@...lia.com>, Raspberry Pi Kernel Maintenance <kernel-list@...pberrypi.com>, 
	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>, 
	dri-devel@...ts.freedesktop.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v3 08/10] drm/display: bridge-connector: handle CEC
 adapters

On Tue, Jan 28, 2025 at 05:14:06PM +0100, Maxime Ripard wrote:
> On Sun, Jan 26, 2025 at 03:29:13PM +0200, Dmitry Baryshkov wrote:
> >  /* -----------------------------------------------------------------------------
> >   * Bridge Connector Initialisation
> >   */
> > @@ -633,6 +711,21 @@ struct drm_connector *drm_bridge_connector_init(struct drm_device *drm,
> >  			if (ret)
> >  				return ERR_PTR(ret);
> >  		}
> > +
> > +		if (bridge->hdmi_cec_adapter_name) {
> > +			if (!bridge->funcs->hdmi_cec_enable ||
> > +			    !bridge->funcs->hdmi_cec_log_addr ||
> > +			    !bridge->funcs->hdmi_cec_transmit)
> > +				return ERR_PTR(-EINVAL);
> > +
> > +			ret = drm_connector_hdmi_cec_register(connector,
> > +							      &drm_bridge_connector_hdmi_cec_ops,
> > +							      bridge->hdmi_cec_adapter_name,
> > +							      bridge->hdmi_cec_available_las,
> > +							      bridge->hdmi_dev);
> > +			if (ret)
> > +				return ERR_PTR(ret);
> > +		}
> 
> Maybe we can use a different bridge feature flag to trigger the CEC code
> support instead?

it is possible, but what is the possible usecase? DP drivers should be
using DP_AUX CEC instead. And I think there are no other kinds of
bridges which implement CEC support. Meson driver does something strange
by registering CEC notifier from meson_encoder_hdmi. I think instead
this should be moved to the DW HDMI bridge itself

-- 
With best wishes
Dmitry