From dd3f2a14489828c5bdec4c9a8616343d24955445 Mon Sep 17 00:00:00 2001
From: Dominic Clifton <dominic.clifton@cleanflight.com>
Date: Fri, 30 Jul 2021 14:40:38 +0200
Subject: [PATCH] RTC6705SOFTSPI - Fix null pointer de-reference caused by
 87c8847c13d7f759548c2384e400d2bc387b159a

---
 src/main/drivers/vtx_rtc6705.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/src/main/drivers/vtx_rtc6705.c b/src/main/drivers/vtx_rtc6705.c
index f0a68a49b4..76ab950b4c 100644
--- a/src/main/drivers/vtx_rtc6705.c
+++ b/src/main/drivers/vtx_rtc6705.c
@@ -110,7 +110,9 @@ bool rtc6705IOInit(const vtxIOConfig_t *vtxIOConfig)
         IOConfigGPIO(vtxPowerPin, IOCFG_OUT_PP);
     }
 
-    if (vtxIOConfig->csTag && spiSetBusInstance(dev, vtxIOConfig->spiDevice)) {
+    // RTC6705 when using SOFT SPI driver doesn't use an SPI device, so don't attempt to initialise an spiInstance.
+    SPI_TypeDef *spiInstance = spiInstanceByDevice(SPI_CFG_TO_DEV(vtxIOConfig->spiDevice));
+    if (spiInstance && spiSetBusInstance(dev, vtxIOConfig->spiDevice)) {
         devInstance.busType_u.spi.csnPin = csnPin;
         IOInit(devInstance.busType_u.spi.csnPin, OWNER_VTX_CS, 0);