serdev: Do not return -ENODEV from of_serdev_register_devices() if external connector...

If an external connector like M.2 is connected to the serdev controller
in DT, then the serdev devices may be created dynamically by the connector
driver. So do not return -ENODEV from of_serdev_register_devices() if the
static nodes are not found and the graph node is used.

Tested-by: Hans de Goede <johannes.goede@oss.qualcomm.com> # ThinkPad T14s gen6 (arm64)
Reviewed-by: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>
Signed-off-by: Manivannan Sadhasivam <manivannan.sadhasivam@oss.qualcomm.com>
Reviewed-by: Rob Herring (Arm) <robh@kernel.org>
Link: https://patch.msgid.link/20260326-pci-m2-e-v7-3-43324a7866e6@oss.qualcomm.com
Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@oss.qualcomm.com>

diff --git a/drivers/tty/serdev/core.c b/drivers/tty/serdev/core.c
index bf88b95f7458d1267bffd3d9690ec0763a5b5a83..e9d044a331b0371be919ce47888e7abca5d96b20 100644 (file)
--- a/drivers/tty/serdev/core.c
+++ b/drivers/tty/serdev/core.c
@@ -12,6 +12,7 @@
 #include <linux/kernel.h>
 #include <linux/module.h>
 #include <linux/of.h>
+#include <linux/of_graph.h>
 #include <linux/of_device.h>
 #include <linux/pm_domain.h>
 #include <linux/pm_runtime.h>
@@ -561,7 +562,13 @@ static int of_serdev_register_devices(struct serdev_controller *ctrl)
                } else
                        found = true;
        }
-       if (!found)
+
+       /*
+        * When the serdev controller is connected to an external connector like
+        * M.2 in DT, then the serdev devices may be created dynamically by the
+        * connector driver.
+        */
+       if (!found && !of_graph_is_present(dev_of_node(&ctrl->dev)))
                return -ENODEV;
 
        return 0;