UARTs which do not trigger THRE interrupt if the fifo is already empty when the interrupt is enabled need tx primed manually. These UARTs are identified by the UART_BUG_TXEN flag to enable the required workaround. However, the current workaround is broken; if the fifo is already empty but the shifter is still transmitting, then serial8250_tx_chars() will not be called but no further THRE interrupt will occur, and tx will stall. The appropriate check is for fifo empty (THRE), not transmitter empty (TEMT). Signed-off-by: Dick Hollenbeck <dick@xxxxxxxxxxx> [pjh: rewrote commit log] Signed-off-by: Peter Hurley <peter@xxxxxxxxxxxxxxxxxx> --- drivers/tty/serial/8250/8250_core.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/drivers/tty/serial/8250/8250_core.c b/drivers/tty/serial/8250/8250_core.c index 285694b..0c61a9b 100644 --- a/drivers/tty/serial/8250/8250_core.c +++ b/drivers/tty/serial/8250/8250_core.c @@ -1365,7 +1365,7 @@ static void serial8250_start_tx(struct uart_port *port) unsigned char lsr; lsr = serial_in(up, UART_LSR); up->lsr_saved_flags |= lsr & LSR_SAVE_FLAGS; - if (lsr & UART_LSR_TEMT) + if (lsr & UART_LSR_THRE) serial8250_tx_chars(up); } } -- 2.2.2 -- To unsubscribe from this list: send the line "unsubscribe linux-serial" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
