diff --git a/drivers/remoteproc/ti_k3_r5_remoteproc.c b/drivers/remoteproc/ti_k3_r5_remoteproc.c
index 26362a509ae3..157e8fd57665 100644
--- a/drivers/remoteproc/ti_k3_r5_remoteproc.c
+++ b/drivers/remoteproc/ti_k3_r5_remoteproc.c
@@ -391,6 +391,7 @@ static int k3_r5_rproc_request_mbox(struct rproc *rproc)
 	struct mbox_client *client = &kproc->client;
 	struct device *dev = kproc->dev;
 	int ret;
+	long err;
 
 	client->dev = dev;
 	client->tx_done = NULL;
@@ -400,10 +401,9 @@ static int k3_r5_rproc_request_mbox(struct rproc *rproc)
 
 	kproc->mbox = mbox_request_channel(client, 0);
 	if (IS_ERR(kproc->mbox)) {
-		ret = -EBUSY;
-		dev_err(dev, "mbox_request_channel failed: %ld\n",
-			PTR_ERR(kproc->mbox));
-		return ret;
+		err = PTR_ERR(kproc->mbox);
+		dev_err(dev, "mbox_request_channel failed: %ld\n", err);
+		return (err == -EPROBE_DEFER) ? -EPROBE_DEFER : -EBUSY;
 	}
 
 	/*
@@ -552,10 +552,6 @@ static int k3_r5_rproc_start(struct rproc *rproc)
 	u32 boot_addr;
 	int ret;
 
-	ret = k3_r5_rproc_request_mbox(rproc);
-	if (ret)
-		return ret;
-
 	boot_addr = rproc->bootaddr;
 	/* TODO: add boot_addr sanity checking */
 	dev_dbg(dev, "booting R5F core using boot addr = 0x%x\n", boot_addr);
@@ -564,7 +560,7 @@ static int k3_r5_rproc_start(struct rproc *rproc)
 	core = kproc->core;
 	ret = ti_sci_proc_set_config(core->tsp, boot_addr, 0, 0);
 	if (ret)
-		goto put_mbox;
+		goto out;
 
 	/* unhalt/run all applicable cores */
 	if (cluster->mode == CLUSTER_MODE_LOCKSTEP) {
@@ -581,12 +577,12 @@ static int k3_r5_rproc_start(struct rproc *rproc)
 			dev_err(dev, "%s: can not start core 1 before core 0\n",
 				__func__);
 			ret = -EPERM;
-			goto put_mbox;
+			goto out;
 		}
 
 		ret = k3_r5_core_run(core);
 		if (ret)
-			goto put_mbox;
+			goto out;
 	}
 
 	return 0;
@@ -596,8 +592,7 @@ static int k3_r5_rproc_start(struct rproc *rproc)
 		if (k3_r5_core_halt(core))
 			dev_warn(core->dev, "core halt back failed\n");
 	}
-put_mbox:
-	mbox_free_channel(kproc->mbox);
+out:
 	return ret;
 }
 
@@ -658,8 +653,6 @@ static int k3_r5_rproc_stop(struct rproc *rproc)
 			goto out;
 	}
 
-	mbox_free_channel(kproc->mbox);
-
 	return 0;
 
 unroll_core_halt:
@@ -674,42 +667,21 @@ static int k3_r5_rproc_stop(struct rproc *rproc)
 /*
  * Attach to a running R5F remote processor (IPC-only mode)
  *
- * The R5F attach callback only needs to request the mailbox, the remote
- * processor is already booted, so there is no need to issue any TI-SCI
- * commands to boot the R5F cores in IPC-only mode. This callback is invoked
- * only in IPC-only mode.
+ * The R5F attach callback is a NOP. The remote processor is already booted, and
+ * all required resources have been acquired during probe routine, so there is
+ * no need to issue any TI-SCI commands to boot the R5F cores in IPC-only mode.
+ * This callback is invoked only in IPC-only mode and exists for sanity sake.
  */
-static int k3_r5_rproc_attach(struct rproc *rproc)
-{
-	struct k3_r5_rproc *kproc = rproc->priv;
-	struct device *dev = kproc->dev;
-	int ret;
-
-	ret = k3_r5_rproc_request_mbox(rproc);
-	if (ret)
-		return ret;
-
-	dev_info(dev, "R5F core initialized in IPC-only mode\n");
-	return 0;
-}
+static int k3_r5_rproc_attach(struct rproc *rproc) { return 0; }
 
 /*
  * Detach from a running R5F remote processor (IPC-only mode)
  *
- * The R5F detach callback performs the opposite operation to attach callback
- * and only needs to release the mailbox, the R5F cores are not stopped and
- * will be left in booted state in IPC-only mode. This callback is invoked
- * only in IPC-only mode.
+ * The R5F detach callback is a NOP. The R5F cores are not stopped and will be
+ * left in booted state in IPC-only mode. This callback is invoked only in
+ * IPC-only mode and exists for sanity sake.
  */
-static int k3_r5_rproc_detach(struct rproc *rproc)
-{
-	struct k3_r5_rproc *kproc = rproc->priv;
-	struct device *dev = kproc->dev;
-
-	mbox_free_channel(kproc->mbox);
-	dev_info(dev, "R5F core deinitialized in IPC-only mode\n");
-	return 0;
-}
+static int k3_r5_rproc_detach(struct rproc *rproc) { return 0; }
 
 /*
  * This function implements the .get_loaded_rsc_table() callback and is used
@@ -1277,6 +1249,10 @@ static int k3_r5_cluster_rproc_init(struct platform_device *pdev)
 		kproc->rproc = rproc;
 		core->rproc = rproc;
 
+		ret = k3_r5_rproc_request_mbox(rproc);
+		if (ret)
+			return ret;
+
 		ret = k3_r5_rproc_configure_mode(kproc);
 		if (ret < 0)
 			goto err_config;
