[PATCH] rpmsg: glink: Split protocol start out of native_probe

[Chunkai Deng]

The SMEM and RPM transports request their receive interrupt with
IRQF_NO_AUTOEN and enable it only after qcom_glink_native_probe()
returns. Since native_probe() sends the initial version command, the
remote may ACK before the local IRQ is enabled, stalling the version
handshake on a fast remote.

Split the protocol start (qcom_glink_send_version() and
qcom_glink_create_chrdev()) into a new qcom_glink_native_start().
Transports now enable their IRQ first, then call native_start(), so the
version ACK is guaranteed to be serviced.

Signed-off-by: Chunkai Deng <chunkai.deng@xxxxxxxxxxxxxxxx>
---
 drivers/rpmsg/qcom_glink_native.c | 32 ++++++++++++++++++++++++++++----
 drivers/rpmsg/qcom_glink_native.h |  1 +
 drivers/rpmsg/qcom_glink_rpm.c    |  8 ++++++++
 drivers/rpmsg/qcom_glink_smem.c   |  8 ++++++++
 4 files changed, 45 insertions(+), 4 deletions(-)

diff --git a/drivers/rpmsg/qcom_glink_native.c b/drivers/rpmsg/qcom_glink_native.c
index d9d4468e4cbd..2a284b22a037 100644
--- a/drivers/rpmsg/qcom_glink_native.c
+++ b/drivers/rpmsg/qcom_glink_native.c
@@ -1928,17 +1928,41 @@ struct qcom_glink *qcom_glink_native_probe(struct device *dev,
 	if (ret)
 		dev_err(dev, "failed to add groups\n");
 
+	return glink;
+}
+EXPORT_SYMBOL_GPL(qcom_glink_native_probe);
+
+/**
+ * qcom_glink_native_start() - start the GLINK protocol handshake
+ * @glink:	glink handle returned by qcom_glink_native_probe()
+ *
+ * Send the initial version command and register the chrdev. This is split
+ * out from qcom_glink_native_probe() so that a transport can enable its
+ * receive interrupt before the version handshake is initiated, ensuring the
+ * version ACK from the remote is not missed.
+ *
+ * Failure to register the chrdev is not fatal and only logged, matching the
+ * previous behaviour of qcom_glink_native_probe().
+ *
+ * Return: 0 on success, negative errno if sending the version command failed.
+ */
+int qcom_glink_native_start(struct qcom_glink *glink)
+{
+	int ret;
+
 	ret = qcom_glink_send_version(glink);
-	if (ret)
-		return ERR_PTR(ret);
+	if (ret) {
+		dev_err(glink->dev, "failed to send version: %d\n", ret);
+		return ret;
+	}
 
 	ret = qcom_glink_create_chrdev(glink);
 	if (ret)
 		dev_err(glink->dev, "failed to register chrdev\n");
 
-	return glink;
+	return 0;
 }
-EXPORT_SYMBOL_GPL(qcom_glink_native_probe);
+EXPORT_SYMBOL_GPL(qcom_glink_native_start);
 
 static int qcom_glink_remove_device(struct device *dev, void *data)
 {
diff --git a/drivers/rpmsg/qcom_glink_native.h b/drivers/rpmsg/qcom_glink_native.h
index 8dbec24de23e..783209980c3a 100644
--- a/drivers/rpmsg/qcom_glink_native.h
+++ b/drivers/rpmsg/qcom_glink_native.h
@@ -35,6 +35,7 @@ struct qcom_glink *qcom_glink_native_probe(struct device *dev,
 					   struct qcom_glink_pipe *rx,
 					   struct qcom_glink_pipe *tx,
 					   bool intentless);
+int qcom_glink_native_start(struct qcom_glink *glink);
 void qcom_glink_native_remove(struct qcom_glink *glink);
 void qcom_glink_native_rx(struct qcom_glink *glink);
 
diff --git a/drivers/rpmsg/qcom_glink_rpm.c b/drivers/rpmsg/qcom_glink_rpm.c
index e3ba2c63a5fc..34f18c3e58c8 100644
--- a/drivers/rpmsg/qcom_glink_rpm.c
+++ b/drivers/rpmsg/qcom_glink_rpm.c
@@ -358,6 +358,14 @@ static int glink_rpm_probe(struct platform_device *pdev)
 
 	enable_irq(rpm->irq);
 
+	ret = qcom_glink_native_start(glink);
+	if (ret) {
+		disable_irq(rpm->irq);
+		qcom_glink_native_remove(glink);
+		mbox_free_channel(rpm->mbox_chan);
+		return ret;
+	}
+
 	return 0;
 }
 
diff --git a/drivers/rpmsg/qcom_glink_smem.c b/drivers/rpmsg/qcom_glink_smem.c
index 62adc4db2317..28f6cfda6352 100644
--- a/drivers/rpmsg/qcom_glink_smem.c
+++ b/drivers/rpmsg/qcom_glink_smem.c
@@ -348,8 +348,16 @@ struct qcom_glink_smem *qcom_glink_smem_register(struct device *parent,
 
 	enable_irq(smem->irq);
 
+	ret = qcom_glink_native_start(glink);
+	if (ret)
+		goto err_disable_irq;
+
 	return smem;
 
+err_disable_irq:
+	disable_irq(smem->irq);
+	qcom_glink_native_remove(glink);
+
 err_free_mbox:
 	mbox_free_channel(smem->mbox_chan);
 

---
base-commit: a225caacc36546a09586e3ece36c0313146e7da9
change-id: 20260604-rpmsg-glink-split-protocol-start-3df74dbd5c94

Best regards,
--  
Chunkai Deng <chunkai.deng@xxxxxxxxxxxxxxxx>