drm/mxsfb: Update mxsfb to support a bridge

Currently, the MXSFB DRM driver only supports a panel. But, its output
display signal can also be redirected to another encoder, like a DSI
controller. In this case, that DSI controller may act like a drm_bridge.
In order support this use-case too, this patch adds support for drm_bridge
in mxsfb.
Signed-off-by: Robert Chiras <robert.chiras@nxp.com>
Tested-by: Guido Günther <agx@sigxcpu.org>
Signed-off-by: Stefan Agner <stefan@agner.ch>
Link: https://patchwork.freedesktop.org/patch/msgid/1567078215-31601-2-git-send-email-robert.chiras@nxp.com

drivers/gpu/drm/mxsfb/mxsfb_crtc.c

@@ -95,8 +95,11 @@ static void mxsfb_set_bus_fmt(struct mxsfb_drm_private *mxsfb)
 
 	reg = readl(mxsfb->base + LCDC_CTRL);
 
-	if (mxsfb->connector.display_info.num_bus_formats)
-		bus_format = mxsfb->connector.display_info.bus_formats[0];
+	if (mxsfb->connector->display_info.num_bus_formats)
+		bus_format = mxsfb->connector->display_info.bus_formats[0];
+
+	DRM_DEV_DEBUG_DRIVER(drm->dev, "Using bus_format: 0x%08X\n",
+			     bus_format);
 
 	reg &= ~CTRL_BUS_WIDTH_MASK;
 	switch (bus_format) {
@@ -204,8 +207,9 @@ static dma_addr_t mxsfb_get_fb_paddr(struct mxsfb_drm_private *mxsfb)
 
 static void mxsfb_crtc_mode_set_nofb(struct mxsfb_drm_private *mxsfb)
 {
+	struct drm_device *drm = mxsfb->pipe.crtc.dev;
 	struct drm_display_mode *m = &mxsfb->pipe.crtc.state->adjusted_mode;
-	const u32 bus_flags = mxsfb->connector.display_info.bus_flags;
+	const u32 bus_flags = mxsfb->connector->display_info.bus_flags;
 	u32 vdctrl0, vsync_pulse_len, hsync_pulse_len;
 	int err;
 
@@ -229,6 +233,13 @@ static void mxsfb_crtc_mode_set_nofb(struct mxsfb_drm_private *mxsfb)
 
 	clk_set_rate(mxsfb->clk, m->crtc_clock * 1000);
 
+	DRM_DEV_DEBUG_DRIVER(drm->dev, "Pixel clock: %dkHz (actual: %dkHz)\n",
+			     m->crtc_clock,
+			     (int)(clk_get_rate(mxsfb->clk) / 1000));
+	DRM_DEV_DEBUG_DRIVER(drm->dev, "Connector bus_flags: 0x%08X\n",
+			     bus_flags);
+	DRM_DEV_DEBUG_DRIVER(drm->dev, "Mode flags: 0x%08X\n", m->flags);
+
 	writel(TRANSFER_COUNT_SET_VCOUNT(m->crtc_vdisplay) |
 	       TRANSFER_COUNT_SET_HCOUNT(m->crtc_hdisplay),
 	       mxsfb->base + mxsfb->devdata->transfer_count);

drivers/gpu/drm/mxsfb/mxsfb_drv.c

@@ -101,9 +101,25 @@ static void mxsfb_pipe_enable(struct drm_simple_display_pipe *pipe,
 			      struct drm_crtc_state *crtc_state,
 			      struct drm_plane_state *plane_state)
 {
+	struct drm_connector *connector;
 	struct mxsfb_drm_private *mxsfb = drm_pipe_to_mxsfb_drm_private(pipe);
 	struct drm_device *drm = pipe->plane.dev;
 
+	if (!mxsfb->connector) {
+		list_for_each_entry(connector,
+				    &drm->mode_config.connector_list,
+				    head)
+			if (connector->encoder == &mxsfb->pipe.encoder) {
+				mxsfb->connector = connector;
+				break;
+			}
+	}
+
+	if (!mxsfb->connector) {
+		dev_warn(drm->dev, "No connector attached, using default\n");
+		mxsfb->connector = &mxsfb->panel_connector;
+	}
+
 	pm_runtime_get_sync(drm->dev);
 	drm_panel_prepare(mxsfb->panel);
 	mxsfb_crtc_enable(mxsfb);
@@ -129,6 +145,9 @@ static void mxsfb_pipe_disable(struct drm_simple_display_pipe *pipe)
 		drm_crtc_send_vblank_event(crtc, event);
 	}
 	spin_unlock_irq(&drm->event_lock);
+
+	if (mxsfb->connector != &mxsfb->panel_connector)
+		mxsfb->connector = NULL;
 }
 
 static void mxsfb_pipe_update(struct drm_simple_display_pipe *pipe,
@@ -226,16 +245,33 @@ static int mxsfb_load(struct drm_device *drm, unsigned long flags)
 
 	ret = drm_simple_display_pipe_init(drm, &mxsfb->pipe, &mxsfb_funcs,
 			mxsfb_formats, ARRAY_SIZE(mxsfb_formats), NULL,
-			&mxsfb->connector);
+			mxsfb->connector);
 	if (ret < 0) {
 		dev_err(drm->dev, "Cannot setup simple display pipe\n");
 		goto err_vblank;
 	}
 
-	ret = drm_panel_attach(mxsfb->panel, &mxsfb->connector);
-	if (ret) {
-		dev_err(drm->dev, "Cannot connect panel\n");
-		goto err_vblank;
+	/*
+	 * Attach panel only if there is one.
+	 * If there is no panel attach, it must be a bridge. In this case, we
+	 * need a reference to its connector for a proper initialization.
+	 * We will do this check in pipe->enable(), since the connector won't
+	 * be attached to an encoder until then.
+	 */
+
+	if (mxsfb->panel) {
+		ret = drm_panel_attach(mxsfb->panel, mxsfb->connector);
+		if (ret) {
+			dev_err(drm->dev, "Cannot connect panel: %d\n", ret);
+			goto err_vblank;
+		}
+	} else if (mxsfb->bridge) {
+		ret = drm_simple_display_pipe_attach_bridge(&mxsfb->pipe,
+							    mxsfb->bridge);
+		if (ret) {
+			dev_err(drm->dev, "Cannot connect bridge: %d\n", ret);
+			goto err_vblank;
+		}
 	}
 
 	drm->mode_config.min_width	= MXSFB_MIN_XRES;

drivers/gpu/drm/mxsfb/mxsfb_drv.h

@@ -27,8 +27,10 @@ struct mxsfb_drm_private {
 	struct clk			*clk_disp_axi;
 
 	struct drm_simple_display_pipe	pipe;
-	struct drm_connector		connector;
+	struct drm_connector		panel_connector;
+	struct drm_connector		*connector;
 	struct drm_panel		*panel;
+	struct drm_bridge		*bridge;
 };
 
 int mxsfb_setup_crtc(struct drm_device *dev);

drivers/gpu/drm/mxsfb/mxsfb_out.c

@@ -21,7 +21,8 @@
 static struct mxsfb_drm_private *
 drm_connector_to_mxsfb_drm_private(struct drm_connector *connector)
 {
-	return container_of(connector, struct mxsfb_drm_private, connector);
+	return container_of(connector, struct mxsfb_drm_private,
+			    panel_connector);
 }
 
 static int mxsfb_panel_get_modes(struct drm_connector *connector)
@@ -76,22 +77,23 @@ static const struct drm_connector_funcs mxsfb_panel_connector_funcs = {
 int mxsfb_create_output(struct drm_device *drm)
 {
 	struct mxsfb_drm_private *mxsfb = drm->dev_private;
-	struct drm_panel *panel;
 	int ret;
 
-	ret = drm_of_find_panel_or_bridge(drm->dev->of_node, 0, 0, &panel, NULL);
+	ret = drm_of_find_panel_or_bridge(drm->dev->of_node, 0, 0,
+					  &mxsfb->panel, &mxsfb->bridge);
 	if (ret)
 		return ret;
 
-	mxsfb->connector.dpms = DRM_MODE_DPMS_OFF;
-	mxsfb->connector.polled = 0;
-	drm_connector_helper_add(&mxsfb->connector,
-			&mxsfb_panel_connector_helper_funcs);
-	ret = drm_connector_init(drm, &mxsfb->connector,
-				 &mxsfb_panel_connector_funcs,
-				 DRM_MODE_CONNECTOR_Unknown);
-	if (!ret)
-		mxsfb->panel = panel;
+	if (mxsfb->panel) {
+		mxsfb->connector = &mxsfb->panel_connector;
+		mxsfb->connector->dpms = DRM_MODE_DPMS_OFF;
+		mxsfb->connector->polled = 0;
+		drm_connector_helper_add(mxsfb->connector,
+					 &mxsfb_panel_connector_helper_funcs);
+		ret = drm_connector_init(drm, mxsfb->connector,
+					 &mxsfb_panel_connector_funcs,
+					 DRM_MODE_CONNECTOR_Unknown);
+	}
 
 	return ret;
 }