From 59203f078cc60a1c2d00d73a64536c8c6b0fb8d8 Mon Sep 17 00:00:00 2001 From: Hoan Nguyen An Date: Mon, 18 Mar 2019 18:26:32 +0900 Subject: [PATCH] serial: sh-sci: Fix setting SCSCR_TIE while transferring data commit 93bcefd4c6bad4c69dbc4edcd3fbf774b24d930d upstream. We disable transmission interrupt (clear SCSCR_TIE) after all data has been transmitted (if uart_circ_empty(xmit)). While transmitting, if the data is still in the tty buffer, re-enable the SCSCR_TIE bit, which was done at sci_start_tx(). This is unnecessary processing, wasting CPU operation if the data transmission length is large. And further, transmit end, FIFO empty bits disabling have also been performed in the step above. Signed-off-by: Hoan Nguyen An Cc: stable Signed-off-by: Greg Kroah-Hartman --- drivers/tty/serial/sh-sci.c | 12 +----------- 1 file changed, 1 insertion(+), 11 deletions(-) diff --git a/drivers/tty/serial/sh-sci.c b/drivers/tty/serial/sh-sci.c index 859b173..cbbf239 100644 --- a/drivers/tty/serial/sh-sci.c +++ b/drivers/tty/serial/sh-sci.c @@ -838,19 +838,9 @@ static void sci_transmit_chars(struct uart_port *port) if (uart_circ_chars_pending(xmit) < WAKEUP_CHARS) uart_write_wakeup(port); - if (uart_circ_empty(xmit)) { + if (uart_circ_empty(xmit)) sci_stop_tx(port); - } else { - ctrl = serial_port_in(port, SCSCR); - - if (port->type != PORT_SCI) { - serial_port_in(port, SCxSR); /* Dummy read */ - sci_clear_SCxSR(port, SCxSR_TDxE_CLEAR(port)); - } - ctrl |= SCSCR_TIE; - serial_port_out(port, SCSCR, ctrl); - } } /* On SH3, SCIF may read end-of-break as a space->mark char */ -- 2.7.4