drm: apple: Use typec mux to switch atc-phy into DP

The upstream atc phy driver has no longer special handling for the phy
only use case on 14/16-inch Macbook Pros. So simply let dcp handle this
and switch the type-c mux to full 4 lane DisplayPort mode.
This requires devicetree changes in the form of a graph based connection
between dcpext0 and atc-phy.

Signed-off-by: Janne Grunau <j@jannau.net>

Author: jannau

drivers/gpu/drm/apple/apple_drv.c

@@ -735,6 +735,17 @@ static int add_dcp_components(struct device *dev,
 					continue;
 				}
 #endif
+
+				/*
+				 * The ATC phy driver is not part of the component
+				 * collection for the Apple display-subsystem so
+				 * ignore it here.
+				 */
+				if (of_device_is_compatible(port, "apple,t8103-atcphy")) {
+					of_node_put(port);
+					continue;
+				}
+
 				if (of_device_is_available(port))
 					drm_of_component_match_add(dev, matchptr,
 							   component_compare_of,

drivers/gpu/drm/apple/dcp-internal.h

@@ -12,6 +12,7 @@
 #include <linux/phy/phy.h>
 #include <linux/platform_device.h>
 #include <linux/scatterlist.h>
+#include <linux/usb/typec_mux.h>
 
 #include "dptxep.h"
 #include "iomfb.h"
@@ -252,6 +253,7 @@ struct apple_dcp {
 	/* these fields are output port specific */
 	struct phy *phy;
 	struct mux_control *xbar;
+	struct typec_mux *typec_mux;
 
 	struct gpio_desc *hdmi_hpd;
 	struct gpio_desc *hdmi_pwren;

drivers/gpu/drm/apple/dcp.c

@@ -21,6 +21,9 @@
 #include <linux/slab.h>
 #include <linux/soc/apple/rtkit.h>
 #include <linux/string.h>
+#include <linux/usb/typec_altmode.h>
+#include <linux/usb/typec_dp.h>
+#include <linux/usb/typec_mux.h>
 #include <linux/workqueue.h>
 
 #include <drm/drm_fb_dma_helper.h>
@@ -1094,6 +1097,8 @@ static void dcp_comp_unbind(struct device *dev, struct device *main, void *data)
 	if (dcp->hdmi_hpd_irq)
 		disable_irq(dcp->hdmi_hpd_irq);
 
+	typec_mux_put(dcp->typec_mux);
+
 	if (dcp->avep) {
 		av_service_disconnect(dcp);
 		afk_shutdown(dcp->avep);
@@ -1231,6 +1236,27 @@ static int dcp_platform_probe(struct platform_device *pdev)
 			ret = mux_control_select(dcp->xbar, mux_index);
 			if (ret)
 				dev_warn(dev, "mux_control_select failed: %d\n", ret);
+
+			/*
+			 * Switch atcphy to DP-only. should move to a Macbook Pro
+			 * 14-/16-inch specific DP-to-HDMI drm_bridge.
+			 */
+			dcp->typec_mux = fwnode_typec_mux_get(dev_fwnode(dcp->dev));
+			if (!IS_ERR_OR_NULL(dcp->typec_mux)) {
+				struct typec_altmode alt = {
+					.svid = USB_TYPEC_DP_SID,
+				};
+				struct typec_mux_state state = {
+					.alt = &alt,
+					.mode = TYPEC_DP_STATE_C,
+				};
+				int ret = typec_mux_set(dcp->typec_mux, &state);
+				dev_info(dev, "typec_mux_set() returned: %d\n", ret);
+			} else {
+				dev_info(dev, "fwnode_typec_mux_get() returned: %ld\n",
+						IS_ERR(dcp->typec_mux) ? PTR_ERR(dcp->typec_mux) : 0);
+				dcp->typec_mux = NULL;
+			}
 		}
 	}
 

drivers/gpu/drm/apple/dptxep.c

@@ -479,7 +479,9 @@ dptxport_call_activate(struct apple_epic_service *service,
 	const struct apple_dcp *dcp = service->ep->dcp;
 
 	// TODO: hack, use phy_set_mode to select the correct DCP(EXT) input
-	phy_set_mode_ext(dptx->atcphy, PHY_MODE_DP, dcp->index);
+	// for standalone phy (i.e. not atc phy).
+	if (!dcp->typec_mux)
+		phy_set_mode_ext(dptx->atcphy, PHY_MODE_DP, dcp->index);
 
 	memcpy(reply, data, min(reply_size, data_size));
 	if (reply_size >= 4)