From 63895d8b0cf8cf6a4d76ad9baa2d677a66c6494a Mon Sep 17 00:00:00 2001
From: Andrew Tridgell <andrew@tridgell.net>
Date: Sun, 10 Mar 2019 20:32:32 +1100
Subject: [PATCH] HAL_ChibiOS: setup dummy pointers for H7 SPI

---
 libraries/AP_HAL_ChibiOS/SPIDevice.cpp | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/libraries/AP_HAL_ChibiOS/SPIDevice.cpp b/libraries/AP_HAL_ChibiOS/SPIDevice.cpp
index 24f9a01f61..662593fa06 100644
--- a/libraries/AP_HAL_ChibiOS/SPIDevice.cpp
+++ b/libraries/AP_HAL_ChibiOS/SPIDevice.cpp
@@ -323,6 +323,13 @@ bool SPIDevice::acquire_bus(bool set, bool skip_cs)
 #if defined(STM32H7)
         bus.spicfg.cfg1 = freq_flag;
         bus.spicfg.cfg2 = device_desc.mode;
+        if (bus.spicfg.dummytx == nullptr) {
+            bus.spicfg.dummytx = (uint32_t *)malloc_dma(4);
+            memset(bus.spicfg.dummytx, 0xFF, 4);
+        }
+        if (bus.spicfg.dummyrx == nullptr) {
+            bus.spicfg.dummyrx = (uint32_t *)malloc_dma(4);
+        }
 #else
         bus.spicfg.cr1 = (uint16_t)(freq_flag | device_desc.mode);
         bus.spicfg.cr2 = 0;