From 787d03c1a36d984f89b6f1ef058e59541a7c3b29 Mon Sep 17 00:00:00 2001
From: Andrew Tridgell <andrew@tridgell.net>
Date: Tue, 11 Jul 2023 19:56:12 +1000
Subject: [PATCH] AP_Mount: prevent SIYI driver crash if serial port not setup

if MNT1_TYPE=8 and no serial protocol set to gimbal then a camera
trigger can crash the vehicle
---
 libraries/AP_Mount/AP_Mount_Siyi.cpp | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/libraries/AP_Mount/AP_Mount_Siyi.cpp b/libraries/AP_Mount/AP_Mount_Siyi.cpp
index dacbb4d1c1..6737c06bbc 100644
--- a/libraries/AP_Mount/AP_Mount_Siyi.cpp
+++ b/libraries/AP_Mount/AP_Mount_Siyi.cpp
@@ -475,6 +475,9 @@ void AP_Mount_Siyi::process_packet()
 // returns true on success, false if outgoing serial buffer is full
 bool AP_Mount_Siyi::send_packet(SiyiCommandId cmd_id, const uint8_t* databuff, uint8_t databuff_len)
 {
+    if (!_initialised) {
+        return false;
+    }
     // calculate and sanity check packet size
     const uint16_t packet_size = AP_MOUNT_SIYI_PACKETLEN_MIN + databuff_len;
     if (packet_size > AP_MOUNT_SIYI_PACKETLEN_MAX) {