From fa7c79712e8dde2ba3277b2c767eeada57f275a5 Mon Sep 17 00:00:00 2001 From: Gregory Nutt Date: Sat, 10 May 2014 10:34:05 -0600 Subject: [PATCH] STM32 I2C: Bring in PX4 fix for I2C in very high noise environments or with rogue perpipherals. Taken from the PX4 commit by Tridge --- arch/arm/src/stm32/Kconfig | 1 - arch/arm/src/stm32/stm32_i2c.c | 14 +++++++++++++- 2 files changed, 13 insertions(+), 2 deletions(-) diff --git a/arch/arm/src/stm32/Kconfig b/arch/arm/src/stm32/Kconfig index b1e0419f45d..8ea719c82de 100644 --- a/arch/arm/src/stm32/Kconfig +++ b/arch/arm/src/stm32/Kconfig @@ -698,7 +698,6 @@ config STM32_STM32F207 default n select STM32_HAVE_OTGFS select STM32_HAVE_FSMC - select STM32_HAVE_CCM select STM32_HAVE_USART3 select STM32_HAVE_USART4 select STM32_HAVE_USART5 diff --git a/arch/arm/src/stm32/stm32_i2c.c b/arch/arm/src/stm32/stm32_i2c.c index 8c3c5487dc1..d745261a741 100644 --- a/arch/arm/src/stm32/stm32_i2c.c +++ b/arch/arm/src/stm32/stm32_i2c.c @@ -1617,7 +1617,14 @@ static int stm32_i2c_process(FAR struct i2c_dev_s *dev, FAR struct i2c_msg_s *ms stm32_i2c_clrstart(priv); - /* Old transfers are done */ + /* Old transfers are done + * + * Reset ptr and dcnt to ensure an unexpected data interrupt doesn't + * overwrite stale data. + */ + + priv->dcnt = 0; + priv->ptr = NULL; priv->msgv = msgs; priv->msgc = count; @@ -1754,6 +1761,11 @@ static int stm32_i2c_process(FAR struct i2c_dev_s *dev, FAR struct i2c_msg_s *ms stm32_i2c_enablefsmc(ahbenr); stm32_i2c_sem_post(dev); + /* Ensure that any ISR happening after we finish can't overwrite any user data */ + + priv->dcnt = 0; + priv->ptr = NULL; + return -errval; }