i3c: master: Defer new-device registration out of DAA caller context

Master drivers may invoke i3c_master_do_daa_ext() during resume to
re-run Dynamic Address Assignment.  As well as assigning addresses to
any newly arrived devices, this restores the dynamic address of devices
that lost it across system suspend, so it has to run as part of the
controller's resume path.

A side effect of i3c_master_do_daa_ext() today is that it also
registers any newly discovered I3C devices with the driver model
inline, via i3c_master_register_new_i3c_devs().  Doing that from the
resume path is problematic: a hot-join-capable device may join the bus
during this same DAA, and registering it immediately would push driver
model work (probing, sysfs, etc.) into the controller's resume context,
where the rest of the system is not yet fully resumed and the
controller driver is still partway through its own resume sequence.

Decouple discovery from registration: add a reg_work work item to
struct i3c_master_controller and have i3c_master_do_daa_ext() queue it
on master->wq (the freezable workqueue) instead of calling
i3c_master_register_new_i3c_devs() directly.  The worker performs the
registration only when the controller is not shutting_down, and is
cancelled alongside hj_work in i3c_master_shutdown().  Because wq is
freezable, any newly observed devices end up being registered after
the system has finished resuming.

i3c_master_register() also routes its initial post-bus-init registration
through reg_work, using flush_work() to keep probe-time behavior
synchronous.  This keeps a single registration code path and ensures the
worker is the only writer of desc->dev.

Fixes: 3a379bbcea0af ("i3c: Add core I3C infrastructure")
Signed-off-by: Adrian Hunter <adrian.hunter@intel.com>
Reviewed-by: Frank Li <Frank.Li@nxp.com>
Link: https://patch.msgid.link/20260608054312.10604-7-adrian.hunter@intel.com
Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>

1 files changed, 20 insertions, 7 deletions

diff --git a/drivers/i3c/master.c b/drivers/i3c/master.c
index c89a1921fcf3..ed749f9ee413 100644
--- a/drivers/i3c/master.c
+++ b/drivers/i3c/master.c
@@ -839,6 +839,7 @@ static void i3c_master_shutdown(struct i3c_master_controller *master)
 	i3c_bus_maintenance_unlock(&master->bus);
 
 	cancel_work_sync(&master->hj_work);
+	cancel_work_sync(&master->reg_work);
 }
 
 static void i3c_device_shutdown(struct device *dev)
@@ -1838,6 +1839,16 @@ i3c_master_register_new_i3c_devs(struct i3c_master_controller *master)
 	}
 }
 
+static void i3c_master_reg_work_fn(struct work_struct *work)
+{
+	struct i3c_master_controller *master = container_of(work, typeof(*master), reg_work);
+
+	i3c_bus_normaluse_lock(&master->bus);
+	if (!master->shutting_down)
+		i3c_master_register_new_i3c_devs(master);
+	i3c_bus_normaluse_unlock(&master->bus);
+}
+
 /**
  * i3c_master_do_daa_ext() - Dynamic Address Assignment (extended version)
  * @master: controller
@@ -1878,9 +1889,7 @@ int i3c_master_do_daa_ext(struct i3c_master_controller *master, bool rstdaa)
 	if (ret)
 		goto out;
 
-	i3c_bus_normaluse_lock(&master->bus);
-	i3c_master_register_new_i3c_devs(master);
-	i3c_bus_normaluse_unlock(&master->bus);
+	queue_work(master->wq, &master->reg_work);
 out:
 	i3c_master_rpm_put(master);
 
@@ -3126,6 +3135,7 @@ int i3c_master_register(struct i3c_master_controller *master,
 		goto err_put_dev;
 	}
 	INIT_WORK(&master->hj_work, i3c_master_hj_work_fn);
+	INIT_WORK(&master->reg_work, i3c_master_reg_work_fn);
 
 	ret = i3c_master_bus_init(master);
 	if (ret)
@@ -3151,12 +3161,15 @@ int i3c_master_register(struct i3c_master_controller *master,
 
 	/*
 	 * We're done initializing the bus and the controller, we can now
-	 * register I3C devices discovered during the initial DAA.
+	 * register I3C devices discovered during the initial DAA. Device
+	 * registration is done via reg_work because that keeps a single
+	 * registration code path and ensures the worker is the only writer
+	 * of desc->dev. Flush the work to preserve synchronous probe-time
+	 * behavior.
 	 */
 	master->init_done = true;
-	i3c_bus_normaluse_lock(&master->bus);
-	i3c_master_register_new_i3c_devs(master);
-	i3c_bus_normaluse_unlock(&master->bus);
+	queue_work(master->wq, &master->reg_work);
+	flush_work(&master->reg_work);
 
 	if (master->ops->set_dev_nack_retry)
 		device_create_file(&master->dev, &dev_attr_dev_nack_retry_count);