patch "serial: sh-sci: Fix setting SCSCR_TIE while transferring data" added to tty-linus

[<gregkh@linuxfoundation.org>]

This is a note to let you know that I've just added the patch titled

    serial: sh-sci: Fix setting SCSCR_TIE while transferring data

to my tty git tree which can be found at
    git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/tty.git
in the tty-linus branch.

The patch will show up in the next release of the linux-next tree
(usually sometime within the next 24 hours during the week.)

The patch will hopefully also be merged in Linus's tree for the
next -rc kernel release.

If you have any questions about this process, please let me know.


From 93bcefd4c6bad4c69dbc4edcd3fbf774b24d930d Mon Sep 17 00:00:00 2001
From: Hoan Nguyen An <na-hoan@jinso.co.jp>
Date: Mon, 18 Mar 2019 18:26:32 +0900
Subject: serial: sh-sci: Fix setting SCSCR_TIE while transferring data

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 <na-hoan@jinso.co.jp>
Cc: stable <stable@vger.kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
 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 060fcd42b6d5..2d1c626312cd 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 */
-- 
2.21.0