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arm/stm32f4: Fix I2C mutex initialization and potential mutex leak

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Fix two issues in the STM32F4 I2C driver related to mutex handling.
The mutex protecting the I2C bus was created with an initial count of
0. For a binary semaphore used as a mutex this causes the first
rtems_semaphore_obtain() call to block indefinitely since the semaphore
starts in the locked state. Initialize the semaphore with a count of 1
so it starts unlocked.
Additionally, stm32f4_i2c_process_message() could return early if the
STOP bit was set in CR1 without releasing the mutex. This would leave
the mutex locked and cause subsequent calls to deadlock. Release the
mutex before returning in this case.
Also cast dummy SR2 reads to (void) to make the intent explicit and
avoid potential compiler warnings about statements with no effect.

arm/stm32f4: Fix I2C mutex initialization and potential mutex leak

fix the indentation on these lines.
This commit is contained in:
Mohamed Ayman
2026-03-18 19:46:21 +00:00
committed by Gedare Bloom
parent 14605b6d2b
commit dc11184541
1 changed files with 6 additions and 5 deletions
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bsps/arm/stm32f4/i2c/i2c.c
+6 -5
View File
@@ -122,7 +122,7 @@ static void stm32f4_i2c_handler(void *arg)
regs->cr1 = cr1;
/* Read sr2 to clear flag */
regs->sr2;
(void) regs->sr2;
cr1 = regs->cr1;
cr1 |= STM32F4_I2C_CR1_STOP;
@@ -135,7 +135,7 @@ static void stm32f4_i2c_handler(void *arg)
/* special case for two bytes */
if(sr1 & STM32F4_I2C_SR1_ADDR) {
/* Read sr2 to clear flag */
regs->sr2;
(void) regs->sr2;
cr1 = regs->cr1;
cr1 &= ~STM32F4_I2C_CR1_ACK;
@@ -154,7 +154,7 @@ static void stm32f4_i2c_handler(void *arg)
/* more than two bytes */
if(sr1 & STM32F4_I2C_SR1_ADDR) {
/* Read sr2 to clear flag */
regs->sr2;
(void) regs->sr2;
} else if(sr1 & STM32F4_I2C_SR1_BTF && data == last - 2) {
cr1 = regs->cr1;
cr1 &= ~STM32F4_I2C_CR1_ACK;
@@ -182,7 +182,7 @@ static void stm32f4_i2c_handler(void *arg)
} else /* write */ {
if(sr1 & STM32F4_I2C_SR1_ADDR) {
/* Address sent */
regs->sr2;
(void) regs->sr2;
}
if((sr1 & (STM32F4_I2C_SR1_ADDR | STM32F4_I2C_SR1_TxE)) && (data <= last)) {
@@ -225,7 +225,7 @@ rtems_status_code stm32f4_i2c_init(stm32f4_i2c_bus_entry *e)
/* Create mutex */
sc = rtems_semaphore_create (
rtems_build_name ('I', '2', 'C', '1' + e->index),
0,
1,
RTEMS_BINARY_SEMAPHORE | RTEMS_PRIORITY | RTEMS_INHERIT_PRIORITY,
0,
&e->mutex
@@ -298,6 +298,7 @@ rtems_status_code stm32f4_i2c_process_message(
/* Check if no stop is active. */
if(cr1 & STM32F4_I2C_CR1_STOP) {
rtems_semaphore_release(e->mutex);
return RTEMS_IO_ERROR;
}