Re: [PATCH 4.19 16/52] serial: uartps: Add a timeout to the tx empty wait

Hi!

commit 277375b864e8147975b064b513f491e2a910e66a upstream

In case the cable is not connected then the target gets into an infinite wait for tx empty. Add a timeout to the tx empty wait.

Was this tested? Because it does not work...

Reported-by: Jean-Francois Dagenais jeff.dagenais@gmail.com Signed-off-by: Shubhrajyoti Datta shubhrajyoti.datta@xilinx.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org Cc: stable stable@vger.kernel.org # 4.19 Signed-off-by: Mathieu Poirier mathieu.poirier@linaro.org Signed-off-by: Sasha Levin sashal@kernel.org

@@ -681,16 +683,20 @@ static void cdns_uart_set_termios(struct uart_port *port,

...

• int err;

spin_lock_irqsave(&port->lock, flags); /* Wait for the transmit FIFO to empty before making changes */ if (!(readl(port->membase + CDNS_UART_CR) & CDNS_UART_CR_TX_DIS)) {

• while (!(readl(port->membase + CDNS_UART_SR) &
  

• 		CDNS_UART_SR_TXEMPTY)) {
  

• 	cpu_relax();
  

• err = readl_poll_timeout(port->membase + CDNS_UART_SR,
  

• 			 val, (val & CDNS_UART_SR_TXEMPTY),
  

• 			 1000, TX_TIMEOUT);
  

• if (err) {
  

• 	dev_err(port->dev, "timed out waiting for tx empty");
  

• 	return;
  

  } }

It will return with lock held and interrupts disabled. Mainline takes spinlock later, so it does not have a problem.

Merging 107475685abfdee504bb0ef4824f15797f6d2d4d before this one should fix the problem.

Best regards, Pavel