From c09babfab7ae8c7d79a5dce9d866fbb28b82dde4 Mon Sep 17 00:00:00 2001 From: Peter Hurley <peter@hurleysoftware.com> Date: Mon, 2 Feb 2015 15:47:07 -0500 Subject: [PATCH] serial: 8250: Fix UART_BUG_TXEN workaround 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@softplc.com> [pjh: rewrote commit log] Signed-off-by: Peter Hurley <peter@hurleysoftware.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> --- 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 46ae9fda68b63..e3b9570a1eff8 100644 --- a/drivers/tty/serial/8250/8250_core.c +++ b/drivers/tty/serial/8250/8250_core.c @@ -1388,7 +1388,7 @@ 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); } } -- GitLab