drm/omap: Add infrastructure to support drm_bridge local to DSS outputs

In order to support drm_bridge-based pipeline, the internal HDMI
encoders will need to expose the EDID read operation through the
drm_bridge API, and thus to expose a drm_bridge instance corresponding
to the encoder. The HDMI encoders are however handled as omap_dss_device
instances, which conflicts with this requirement.

In order to move forward with the drm_bridge transition, add support for
creating drm_bridge instances local to DSS outputs. If a local bridge is
passed to the omapdss_device_init_output() function, it is used as the
first bridge in the chain, and the omap_dss_device.next_bridge field is
set to the next bridge for the use of the internal encoders' bridges.
Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Reviewed-by: Tomi Valkeinen <tomi.valkeinen@ti.com>
Tested-by: Sebastian Reichel <sebastian.reichel@collabora.com>
Reviewed-by: Sebastian Reichel <sebastian.reichel@collabora.com>
Signed-off-by: Tomi Valkeinen <tomi.valkeinen@ti.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20200226112514.12455-27-laurent.pinchart@ideasonboard.com

drivers/gpu/drm/omapdrm/dss/dpi.c

@@ -629,7 +629,7 @@ static int dpi_init_output_port(struct dpi_data *dpi, struct device_node *port)
 	out->ops = &dpi_ops;
 	out->owner = THIS_MODULE;
 
-	r = omapdss_device_init_output(out);
+	r = omapdss_device_init_output(out, NULL);
 	if (r < 0)
 		return r;
 

drivers/gpu/drm/omapdrm/dss/dsi.c

@@ -5121,7 +5121,7 @@ static int dsi_init_output(struct dsi_data *dsi)
 		       | DRM_BUS_FLAG_DE_HIGH
 		       | DRM_BUS_FLAG_SYNC_DRIVE_NEGEDGE;
 
-	r = omapdss_device_init_output(out);
+	r = omapdss_device_init_output(out, NULL);
 	if (r < 0)
 		return r;
 

drivers/gpu/drm/omapdrm/dss/hdmi4.c

@@ -676,7 +676,7 @@ static int hdmi4_init_output(struct omap_hdmi *hdmi)
 	out->of_port = 0;
 	out->ops_flags = OMAP_DSS_DEVICE_OP_EDID;
 
-	r = omapdss_device_init_output(out);
+	r = omapdss_device_init_output(out, NULL);
 	if (r < 0)
 		return r;
 

drivers/gpu/drm/omapdrm/dss/hdmi5.c

@@ -660,7 +660,7 @@ static int hdmi5_init_output(struct omap_hdmi *hdmi)
 	out->of_port = 0;
 	out->ops_flags = OMAP_DSS_DEVICE_OP_EDID;
 
-	r = omapdss_device_init_output(out);
+	r = omapdss_device_init_output(out, NULL);
 	if (r < 0)
 		return r;
 

drivers/gpu/drm/omapdrm/dss/omapdss.h

@@ -400,6 +400,7 @@ struct omap_dss_device {
 	struct dss_device *dss;
 	struct omap_dss_device *next;
 	struct drm_bridge *bridge;
+	struct drm_bridge *next_bridge;
 	struct drm_panel *panel;
 
 	struct list_head list;
@@ -488,7 +489,8 @@ int omap_dss_get_num_overlays(void);
 #define for_each_dss_output(d) \
 	while ((d = omapdss_device_next_output(d)) != NULL)
 struct omap_dss_device *omapdss_device_next_output(struct omap_dss_device *from);
-int omapdss_device_init_output(struct omap_dss_device *out);
+int omapdss_device_init_output(struct omap_dss_device *out,
+			       struct drm_bridge *local_bridge);
 void omapdss_device_cleanup_output(struct omap_dss_device *out);
 
 typedef void (*omap_dispc_isr_t) (void *arg, u32 mask);

drivers/gpu/drm/omapdrm/dss/output.c

@@ -17,7 +17,8 @@
 #include "dss.h"
 #include "omapdss.h"
 
-int omapdss_device_init_output(struct omap_dss_device *out)
+int omapdss_device_init_output(struct omap_dss_device *out,
+			       struct drm_bridge *local_bridge)
 {
 	struct device_node *remote_node;
 	int ret;
@@ -58,10 +59,20 @@ int omapdss_device_init_output(struct omap_dss_device *out)
 		out->bridge = bridge;
 	}
 
-	return out->next || out->bridge ? 0 : -EPROBE_DEFER;
+	if (local_bridge) {
+		out->next_bridge = out->bridge;
+		out->bridge = local_bridge;
+	}
+
+	if (!out->next && !out->bridge) {
+		ret = -EPROBE_DEFER;
+		goto error;
+	}
+
+	return 0;
 
 error:
-	omapdss_device_put(out->next);
+	omapdss_device_cleanup_output(out);
 	out->next = NULL;
 	return ret;
 }
@@ -70,7 +81,8 @@ EXPORT_SYMBOL(omapdss_device_init_output);
 void omapdss_device_cleanup_output(struct omap_dss_device *out)
 {
 	if (out->bridge && out->panel)
-		drm_panel_bridge_remove(out->bridge);
+		drm_panel_bridge_remove(out->next_bridge ?
+					out->next_bridge : out->bridge);
 
 	if (out->next)
 		omapdss_device_put(out->next);

drivers/gpu/drm/omapdrm/dss/sdi.c

@@ -271,7 +271,7 @@ static int sdi_init_output(struct sdi_device *sdi)
 	out->bus_flags = DRM_BUS_FLAG_PIXDATA_DRIVE_POSEDGE	/* 15.5.9.1.2 */
 		       | DRM_BUS_FLAG_SYNC_DRIVE_POSEDGE;
 
-	r = omapdss_device_init_output(out);
+	r = omapdss_device_init_output(out, NULL);
 	if (r < 0)
 		return r;
 

drivers/gpu/drm/omapdrm/dss/venc.c

@@ -757,7 +757,7 @@ static int venc_init_output(struct venc_device *venc)
 	out->of_port = 0;
 	out->ops_flags = OMAP_DSS_DEVICE_OP_MODES;
 
-	r = omapdss_device_init_output(out);
+	r = omapdss_device_init_output(out, NULL);
 	if (r < 0)
 		return r;
 

drivers/gpu/drm/omapdrm/omap_drv.c

@@ -324,7 +324,7 @@ static int omap_modeset_init(struct drm_device *dev)
 		struct drm_encoder *encoder = pipe->encoder;
 		struct drm_crtc *crtc;
 
-		if (!pipe->output->bridge) {
+		if (pipe->output->next) {
 			pipe->connector = omap_connector_init(dev, pipe->output,
 							      encoder);
 			if (!pipe->connector)