From: Chaoyi Chen <chaoyi.chen@rock-chips.com>

Using the DRM_AUX_BRIDGE helper to create the transparent DRM bridge
device.

Signed-off-by: Chaoyi Chen <chaoyi.chen@rock-chips.com>
---
 drivers/phy/rockchip/phy-rockchip-typec.c | 52 +++++++++++++++++++++++
 1 file changed, 52 insertions(+)

diff --git a/drivers/phy/rockchip/phy-rockchip-typec.c b/drivers/phy/rockchip/phy-rockchip-typec.c
index 4a1dfa8d65c7..8003a41de5c6 100644
--- a/drivers/phy/rockchip/phy-rockchip-typec.c
+++ b/drivers/phy/rockchip/phy-rockchip-typec.c
@@ -36,6 +36,7 @@
  * orientation, false is normal orientation.
  */
 
+#include <linux/auxiliary_bus.h>
 #include <linux/clk.h>
 #include <linux/clk-provider.h>
 #include <linux/delay.h>
@@ -56,6 +57,7 @@
 #include <linux/phy/phy.h>
 #include <linux/usb/typec_dp.h>
 #include <linux/usb/typec_mux.h>
+#include <drm/bridge/aux-bridge.h>
 
 #define CMN_SSM_BANDGAP			(0x21 << 2)
 #define CMN_SSM_BIAS			(0x22 << 2)
@@ -415,6 +417,7 @@ struct rockchip_usb3phy_port_cfg {
 
 struct rockchip_typec_phy {
 	struct device *dev;
+	struct auxiliary_device dp_port_dev;
 	void __iomem *base;
 	struct extcon_dev *extcon;
 	struct typec_mux_dev *mux;
@@ -1296,6 +1299,51 @@ static void tcphy_typec_mux_unregister(void *data)
 	typec_mux_unregister(tcphy->mux);
 }
 
+static void tcphy_dp_port_dev_release(struct device *dev)
+{
+	struct auxiliary_device *adev = to_auxiliary_dev(dev);
+
+	of_node_put(adev->dev.of_node);
+}
+
+static void tcphy_dp_port_unregister_adev(void *_adev)
+{
+	struct auxiliary_device *adev = _adev;
+
+	auxiliary_device_delete(adev);
+	auxiliary_device_uninit(adev);
+}
+
+static int tcphy_aux_bridge_register(struct rockchip_typec_phy *tcphy, struct device_node *np)
+{
+	struct auxiliary_device *adev = &tcphy->dp_port_dev;
+	int ret;
+
+	adev->name = "dp_port";
+	adev->dev.parent = tcphy->dev;
+	adev->dev.of_node = of_node_get(np);
+	adev->dev.release = tcphy_dp_port_dev_release;
+
+	ret = auxiliary_device_init(adev);
+
+	if (ret) {
+		of_node_put(adev->dev.of_node);
+		return ret;
+	}
+
+	ret = auxiliary_device_add(adev);
+	if (ret) {
+		auxiliary_device_uninit(adev);
+		return ret;
+	}
+
+	devm_add_action_or_reset(tcphy->dev, tcphy_dp_port_unregister_adev, adev);
+
+	ret = drm_aux_bridge_register(&adev->dev);
+
+	return 0;
+}
+
 static int tcphy_setup_typec_mux(struct rockchip_typec_phy *tcphy)
 {
 	struct typec_mux_desc mux_desc = {};
@@ -1309,6 +1357,10 @@ static int tcphy_setup_typec_mux(struct rockchip_typec_phy *tcphy)
 	if (!of_property_read_bool(np, "mode-switch"))
 		goto put_np;
 
+	ret = tcphy_aux_bridge_register(tcphy, np);
+	if (ret)
+		goto put_np;
+
 	mux_desc.drvdata = tcphy;
 	mux_desc.fwnode = device_get_named_child_node(tcphy->dev, "dp-port");
 	mux_desc.set = tcphy_typec_mux_set;
-- 
2.49.0

Hi Chaoyi,

kernel test robot noticed the following build errors:

[auto build test ERROR on usb/usb-testing]
[also build test ERROR on usb/usb-next usb/usb-linus linus/master v6.18-rc1 next-20251013]
[cannot apply to rockchip/for-next robh/for-next]
[If your patch is applied to the wrong git tree, kindly drop us a note.
And when submitting patch, we suggest to use '--base' as documented in
https://git-scm.com/docs/git-format-patch#_base_tree_information]

url:    https://github.com/intel-lab-lkp/linux/commits/Chaoyi-Chen/usb-typec-Add-default-HPD-device-when-register-DisplayPort-altmode/20251011-113608
base:   https://git.kernel.org/pub/scm/linux/kernel/git/gregkh/usb.git usb-testing
patch link:    https://lore.kernel.org/r/20251011033233.97-5-kernel%40airkyi.com
patch subject: [PATCH v5 4/8] phy: rockchip: phy-rockchip-typec: Add DRM AUX bridge
config: i386-buildonly-randconfig-003-20251011 (https://download.01.org/0day-ci/archive/20251013/202510132306.TKsFxaNn-lkp@intel.com/config)
compiler: gcc-14 (Debian 14.2.0-19) 14.2.0
reproduce (this is a W=1 build): (https://download.01.org/0day-ci/archive/20251013/202510132306.TKsFxaNn-lkp@intel.com/reproduce)

If you fix the issue in a separate patch/commit (i.e. not just a new version of
the same patch/commit), kindly add following tags
| Reported-by: kernel test robot <lkp@intel.com>
| Closes: https://lore.kernel.org/oe-kbuild-all/202510132306.TKsFxaNn-lkp@intel.com/

All errors (new ones prefixed by >>):

   ld: drivers/phy/rockchip/phy-rockchip-typec.o: in function `udphy_orien_switch_unregister':
   phy-rockchip-typec.c:(.text+0x89a): undefined reference to `typec_switch_unregister'
   ld: drivers/phy/rockchip/phy-rockchip-typec.o: in function `tcphy_orien_sw_set':
   phy-rockchip-typec.c:(.text+0x8b9): undefined reference to `typec_switch_get_drvdata'
   ld: drivers/phy/rockchip/phy-rockchip-typec.o: in function `tcphy_typec_mux_unregister':
   phy-rockchip-typec.c:(.text+0x93a): undefined reference to `typec_mux_unregister'
   ld: drivers/phy/rockchip/phy-rockchip-typec.o: in function `tcphy_typec_mux_set':
   phy-rockchip-typec.c:(.text+0x959): undefined reference to `typec_mux_get_drvdata'
   ld: drivers/phy/rockchip/phy-rockchip-typec.o: in function `tcphy_setup_typec_mux':
>> phy-rockchip-typec.c:(.text+0xac3): undefined reference to `drm_aux_bridge_register'
   ld: phy-rockchip-typec.c:(.text+0xae6): undefined reference to `typec_mux_register'
   ld: drivers/phy/rockchip/phy-rockchip-typec.o: in function `rockchip_typec_phy_probe':
   phy-rockchip-typec.c:(.text+0xf3f): undefined reference to `typec_switch_register'

-- 
0-DAY CI Kernel Test Service
https://github.com/intel/lkp-tests/wiki