From a1b1ef49471c9d13d6bd50949323d961eb2ccc76 Mon Sep 17 00:00:00 2001
From: Andrew Tridgell <andrew@tridgell.net>
Date: Mon, 30 Dec 2019 14:29:37 +1100
Subject: [PATCH] HAL_ChibiOS: fixed H7 I2C timing

we were running the clock at too low speed. This affected the SSD1306 display

# Conflicts:
#	libraries/AP_HAL_ChibiOS/I2CDevice.cpp
---
 libraries/AP_HAL_ChibiOS/I2CDevice.cpp | 15 +++++++++++++--
 1 file changed, 13 insertions(+), 2 deletions(-)

diff --git a/libraries/AP_HAL_ChibiOS/I2CDevice.cpp b/libraries/AP_HAL_ChibiOS/I2CDevice.cpp
index 01c5e38f40..a838cc4125 100644
--- a/libraries/AP_HAL_ChibiOS/I2CDevice.cpp
+++ b/libraries/AP_HAL_ChibiOS/I2CDevice.cpp
@@ -54,6 +54,9 @@ I2CBus I2CDeviceManager::businfo[ARRAY_SIZE(I2CD)];
 #define HAL_I2C_F7_100_TIMINGR 0x20404768
 #define HAL_I2C_F7_400_TIMINGR 0x6000030D
 
+#define HAL_I2C_H7_100_TIMINGR 0x00707CBB
+#define HAL_I2C_H7_400_TIMINGR 0x00300F38
+
 /*
   enable clear (toggling SCL) on I2C bus timeouts which leave SDA stuck low
  */
@@ -123,7 +126,7 @@ I2CDeviceManager::I2CDeviceManager(void)
           drop the speed to be the minimum speed requested
          */
         businfo[i].busclock = HAL_I2C_MAX_CLOCK;
-#if defined(STM32F7) || defined(STM32H7)
+#if defined(STM32F7)
         if (businfo[i].busclock <= 100000) {
             businfo[i].i2ccfg.timingr = HAL_I2C_F7_100_TIMINGR;
             businfo[i].busclock = 100000;
@@ -131,7 +134,15 @@ I2CDeviceManager::I2CDeviceManager(void)
             businfo[i].i2ccfg.timingr = HAL_I2C_F7_400_TIMINGR;
             businfo[i].busclock = 400000;
         }
-#else
+#elif defined(STM32H7)
+        if (businfo[i].busclock <= 100000) {
+            businfo[i].i2ccfg.timingr = HAL_I2C_H7_100_TIMINGR;
+            businfo[i].busclock = 100000;
+        } else {
+            businfo[i].i2ccfg.timingr = HAL_I2C_H7_400_TIMINGR;
+            businfo[i].busclock = 400000;
+        }
+#else // F1 or F4
         businfo[i].i2ccfg.op_mode = OPMODE_I2C;
         businfo[i].i2ccfg.clock_speed = businfo[i].busclock;
         if (businfo[i].i2ccfg.clock_speed <= 100000) {