firmware: arm_scmi: Fix range check for the maximum number of pending messages

SCMI message headers carry a sequence number and such field is sized to
allow for MSG_TOKEN_MAX distinct numbers; moreover zero is not really an
acceptable maximum number of pending in-flight messages.

Fix accordingly the checks performed on the value exported by transports
in scmi_desc.max_msg

Reported-by: Vincent Guittot <>
Signed-off-by: Cristian Marussi <>
[sudeep.holla: updated the patch title and error message]
Signed-off-by: Sudeep Holla <>
diff --git a/drivers/firmware/arm_scmi/driver.c b/drivers/firmware/arm_scmi/driver.c
index 1cbd2b0..9b2e8d4 100644
--- a/drivers/firmware/arm_scmi/driver.c
+++ b/drivers/firmware/arm_scmi/driver.c
@@ -1026,8 +1026,9 @@
 	const struct scmi_desc *desc = sinfo->desc;
 	/* Pre-allocated messages, no more than what hdr.seq can support */
-	if (WARN_ON(desc->max_msg >= MSG_TOKEN_MAX)) {
-		dev_err(dev, "Maximum message of %d exceeds supported %ld\n",
+	if (WARN_ON(!desc->max_msg || desc->max_msg > MSG_TOKEN_MAX)) {
+		dev_err(dev,
+			"Invalid maximum messages %d, not in range [1 - %lu]\n",
 			desc->max_msg, MSG_TOKEN_MAX);
 		return -EINVAL;