[PATCH v3 6/7] drm/msm/mdp4: switch LVDS to use drm_bridge/_connector

[Dmitry Baryshkov]

On Wed, Apr 23, 2025 at 07:04:16PM -0700, Abhinav Kumar wrote:
> 
> 
> On 2/26/2025 6:25 PM, Dmitry Baryshkov wrote:
> > LVDS support in MDP4 driver makes use of drm_connector directly. However
> > LCDC encoder and LVDS connector are wrappers around drm_panel. Switch
> > them to use drm_panel_bridge/drm_bridge_connector. This allows using
> > standard interface for the drm_panel and also inserting additional
> > bridges between encoder and panel.
> > 
> > Signed-off-by: Dmitry Baryshkov <dmitry.baryshkov at linaro.org>
> > ---
> >   drivers/gpu/drm/msm/Makefile                       |   1 -
> >   drivers/gpu/drm/msm/disp/mdp4/mdp4_kms.c           |  34 +++++--
> >   drivers/gpu/drm/msm/disp/mdp4/mdp4_kms.h           |   6 +-
> >   drivers/gpu/drm/msm/disp/mdp4/mdp4_lcdc_encoder.c  |  20 +----
> >   .../gpu/drm/msm/disp/mdp4/mdp4_lvds_connector.c    | 100 ---------------------
> >   5 files changed, 28 insertions(+), 133 deletions(-)
> > 
> > @@ -199,27 +201,43 @@ static int mdp4_modeset_init_intf(struct mdp4_kms *mdp4_kms,
> >   		 * bail out early if there is no panel node (no need to
> >   		 * initialize LCDC encoder and LVDS connector)
> >   		 */
> > -		panel_node = of_graph_get_remote_node(dev->dev->of_node, 0, 0);
> > -		if (!panel_node)
> > -			return 0;
> > +		next_bridge = devm_drm_of_get_bridge(dev->dev, dev->dev->of_node, 0, 0);
> > +		if (IS_ERR(next_bridge)) {
> > +			ret = PTR_ERR(next_bridge);
> > +			if (ret == -ENODEV)
> > +				return 0;
> > +			return ret;
> > +		}
> > -		encoder = mdp4_lcdc_encoder_init(dev, panel_node);
> > +		encoder = mdp4_lcdc_encoder_init(dev);
> >   		if (IS_ERR(encoder)) {
> >   			DRM_DEV_ERROR(dev->dev, "failed to construct LCDC encoder\n");
> > -			of_node_put(panel_node);
> >   			return PTR_ERR(encoder);
> >   		}
> >   		/* LCDC can be hooked to DMA_P (TODO: Add DMA_S later?) */
> >   		encoder->possible_crtcs = 1 << DMA_P;
> > -		connector = mdp4_lvds_connector_init(dev, panel_node, encoder);
> > +		ret = drm_bridge_attach(encoder, next_bridge, NULL, DRM_BRIDGE_ATTACH_NO_CONNECTOR);
> > +		if (ret) {
> > +			DRM_DEV_ERROR(dev->dev, "failed to attach LVDS panel/bridge: %d\n", ret);
> > +
> > +			return ret;
> > +		}
> 
> Can you pls point me to the lvds bridge used with this apq8064 board? I was
> unable to find it. Just wanted to compare that against this while reviewing.

It's the panel bridge, wrapping one of the LVDS panels.

> > +
> > +		connector = drm_bridge_connector_init(dev, encoder);
> >   		if (IS_ERR(connector)) {
> >   			DRM_DEV_ERROR(dev->dev, "failed to initialize LVDS connector\n");
> > -			of_node_put(panel_node);
> >   			return PTR_ERR(connector);
> >   		}
> > +		ret = drm_connector_attach_encoder(connector, encoder);
> > +		if (ret) {
> > +			DRM_DEV_ERROR(dev->dev, "failed to attach LVDS connector: %d\n", ret);
> > +
> > +			return ret;
> > +		}
> > +
> >   		break;
> >   	case DRM_MODE_ENCODER_TMDS:
> >   		encoder = mdp4_dtv_encoder_init(dev);

-- 
With best wishes
Dmitry