drm/msm/dp: Allow attaching a drm_panel

eDP panels might need some power sequencing and backlight management,
so make it possible to associate a drm_panel with an eDP instance and
prepare and enable the panel accordingly.

Now that we know which hardware instance is DP and which is eDP,
parser->parse() is passed the connector_type and the parser is limited
to only search for a panel in the eDP case.

Signed-off-by: Bjorn Andersson <bjorn.andersson@linaro.org>
Reviewed-by: Stephen Boyd <swboyd@chromium.org>
Link: https://lore.kernel.org/r/20211016221843.2167329-5-bjorn.andersson@linaro.org
Signed-off-by: Rob Clark <robdclark@chromium.org>

drivers/gpu/drm/msm/dp/dp_display.c

@@ -10,6 +10,7 @@
 #include <linux/component.h>
 #include <linux/of_irq.h>
 #include <linux/delay.h>
+#include <drm/drm_panel.h>
 
 #include "msm_drv.h"
 #include "msm_kms.h"
@@ -230,12 +231,14 @@ static int dp_display_bind(struct device *dev, struct device *master,
 	priv = drm->dev_private;
 	priv->dp = &(dp->dp_display);
 
-	rc = dp->parser->parse(dp->parser);
+	rc = dp->parser->parse(dp->parser, dp->dp_display.connector_type);
 	if (rc) {
 		DRM_ERROR("device tree parsing failed\n");
 		goto end;
 	}
 
+	dp->dp_display.panel_bridge = dp->parser->panel_bridge;
+
 	dp->aux->drm_dev = drm;
 	rc = dp_aux_register(dp->aux);
 	if (rc) {
@@ -822,7 +825,7 @@ static int dp_display_set_mode(struct msm_dp *dp_display,
 	return 0;
 }
 
-static int dp_display_prepare(struct msm_dp *dp)
+static int dp_display_prepare(struct msm_dp *dp_display)
 {
 	return 0;
 }
@@ -896,7 +899,7 @@ static int dp_display_disable(struct dp_display_private *dp, u32 data)
 	return 0;
 }
 
-static int dp_display_unprepare(struct msm_dp *dp)
+static int dp_display_unprepare(struct msm_dp *dp_display)
 {
 	return 0;
 }

drivers/gpu/drm/msm/dp/dp_display.h

@@ -15,6 +15,7 @@ struct msm_dp {
 	struct device *codec_dev;
 	struct drm_connector *connector;
 	struct drm_encoder *encoder;
+	struct drm_bridge *panel_bridge;
 	bool is_connected;
 	bool audio_enabled;
 	bool power_on;

drivers/gpu/drm/msm/dp/dp_drm.c

@@ -5,6 +5,7 @@
 
 #include <drm/drm_atomic_helper.h>
 #include <drm/drm_atomic.h>
+#include <drm/drm_bridge.h>
 #include <drm/drm_crtc.h>
 
 #include "msm_drv.h"
@@ -160,5 +161,15 @@ struct drm_connector *dp_drm_connector_init(struct msm_dp *dp_display)
 
 	drm_connector_attach_encoder(connector, dp_display->encoder);
 
+	if (dp_display->panel_bridge) {
+		ret = drm_bridge_attach(dp_display->encoder,
+					dp_display->panel_bridge, NULL,
+					DRM_BRIDGE_ATTACH_NO_CONNECTOR);
+		if (ret < 0) {
+			DRM_ERROR("failed to attach panel bridge: %d\n", ret);
+			return ERR_PTR(ret);
+		}
+	}
+
 	return connector;
 }

drivers/gpu/drm/msm/dp/dp_parser.c

@@ -6,6 +6,7 @@
 #include <linux/of_gpio.h>
 #include <linux/phy/phy.h>
 
+#include <drm/drm_of.h>
 #include <drm/drm_print.h>
 
 #include "dp_parser.h"
@@ -263,7 +264,28 @@ static int dp_parser_clock(struct dp_parser *parser)
 	return 0;
 }
 
-static int dp_parser_parse(struct dp_parser *parser)
+static int dp_parser_find_panel(struct dp_parser *parser)
+{
+	struct device *dev = &parser->pdev->dev;
+	struct drm_panel *panel;
+	int rc;
+
+	rc = drm_of_find_panel_or_bridge(dev->of_node, 1, 0, &panel, NULL);
+	if (rc) {
+		DRM_ERROR("failed to acquire DRM panel: %d\n", rc);
+		return rc;
+	}
+
+	parser->panel_bridge = devm_drm_panel_bridge_add(dev, panel);
+	if (IS_ERR(parser->panel_bridge)) {
+		DRM_ERROR("failed to create panel bridge\n");
+		return PTR_ERR(parser->panel_bridge);
+	}
+
+	return 0;
+}
+
+static int dp_parser_parse(struct dp_parser *parser, int connector_type)
 {
 	int rc = 0;
 
@@ -284,6 +306,12 @@ static int dp_parser_parse(struct dp_parser *parser)
 	if (rc)
 		return rc;
 
+	if (connector_type == DRM_MODE_CONNECTOR_eDP) {
+		rc = dp_parser_find_panel(parser);
+		if (rc)
+			return rc;
+	}
+
 	/* Map the corresponding regulator information according to
 	 * version. Currently, since we only have one supported platform,
 	 * mapping the regulator directly.

drivers/gpu/drm/msm/dp/dp_parser.h

@@ -123,8 +123,9 @@ struct dp_parser {
 	struct dp_display_data disp_data;
 	const struct dp_regulator_cfg *regulator_cfg;
 	u32 max_dp_lanes;
+	struct drm_bridge *panel_bridge;
 
-	int (*parse)(struct dp_parser *parser);
+	int (*parse)(struct dp_parser *parser, int connector_type);
 };
 
 /**