Commit be8c9346 authored by Hoan Nguyen An's avatar Hoan Nguyen An Committed by Greg Kroah-Hartman

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

commit 93bcefd4 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: default avatarHoan Nguyen An <na-hoan@jinso.co.jp>
Cc: stable <stable@vger.kernel.org>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent 0d42abfa
......@@ -806,19 +806,9 @@ 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 */
......
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