Trivially triggered with two or more threads write to regular syslog stream and to emergency stream. In this case, freeze happens because of mismatch of priv->ie (TXEIE == 0) and actually enabled interrupts in USART registers (TXEIE == 1), which leads to unhandled TXE interrupt
and causes interrupt storm for USART.
The reason was that the code hit the line "canerr("ERROR: No available mailbox\n");" in stm32_cansend, so can_xmit thinks it has sent the packet to the hardware, but actually has not. Therefore the transmit interrupt never happens which would call can_txdone, and so the size of the FIFO size does not decrease.
The reason why the code actually hit the mentioned line above, is because stm32can_txready uses a different (incomplete) condition than stm32can_send to determine if the mailbox can be used for sending, and thus can_xmit forwards the packet to stm32can_send. stm32can_txready considered mailboxes OK for sending if the mailbox was empty, but did not consider that mailboxes may not yet be used if the request completed bit is set - stm32can_txinterrupt has to process these mailboxes first.
Note that I have also modified stm32can_txinterrupt - I removed the if condition, because the CAN controller retries to send the packet until it succeeds. Also if the condition would not evaluate to true, can_txdone would not be called and the FIFO size would not decrease also.
The output structure of the GPIO for I2C needs to be open
drain. When left at the default, one can observe on a scope
the slave contending with the push-pull during the ACK
The output structure of the GPIO for I2C needs to be open
drain. When left at the default, one can observe on a scope
the slave contending with the push-pull during the ACK
The output structure of the GPIO for I2C needs to be open
drain. When left at the default, one can observe on a scope
the slave contending with the push-pull during the ACK
The output structure of the GPIO for I2C needs to be open
drain. When left at the default, one can observe on a scope
the slave contending with the push-pull during the ACK
The output structure of the GPIO for I2C needs to be open
drain. When left at the default, one can observe on a scope
the slave contending with the push-pull during the ACK
