[PATCH v3 3/4] drm/lcdif: add DRM_BRIDGE_ATTACH_NO_CONNECTOR flag to drm_bridge_attach

[Dmitry Baryshkov]

On Fri, Jan 03, 2025 at 12:20:19AM +0100, Marek Vasut wrote:
> On 1/2/25 6:58 PM, Dmitry Baryshkov wrote:
> 
> [...]
> 
> > > @@ -97,13 +100,36 @@ static int lcdif_attach_bridge(struct lcdif_drm_private *lcdif)
> > >   			return ret;
> > >   		}
> > > -		ret = drm_bridge_attach(encoder, bridge, NULL, 0);
> > > +		ret = drm_bridge_attach(encoder, bridge, NULL,
> > > +					DRM_BRIDGE_ATTACH_NO_CONNECTOR);
> > >   		if (ret) {
> > >   			of_node_put(ep);
> > >   			return dev_err_probe(dev, ret,
> > >   					     "Failed to attach bridge for endpoint%u\n",
> > >   					     of_ep.id);
> > >   		}
> > > +
> > > +		nextbridge = drm_bridge_get_next_bridge(bridge);
> > > +		nextbridge = drm_bridge_get_next_bridge(nextbridge);
> > > +		/* Test if connector node in DT, if not, it was created already */
> > 
> > By whom? And why?
> 
> By the HDMI bridge driver, see 1/4.
> 
> > There is no display-connector bridge, but there is a
> > normal bridge chain, you have passed DRM_BRIDGE_ATTACH_NO_CONNECTOR, so
> > now it's a proper time to create drm_bridge_connector. You have added
> > the next_bridge_optional flag, but it should just prevent the dw driver
> > from returning the error if there is no next_bridge.
> So what exactly should I do here ?
> 
> If dw_hdmi_parse_dt() only exits with 0 if there is no connector node in DT,
> I don't get any output on the HDMI. I have to create a connector in the HDMI
> bridge driver instead and not here, right ?

No. Please make dw_hdmi_parse_dt() return 0 if there is no connector and
the flag is set. Then create drm_bridge_connector here.


-- 
With best wishes
Dmitry