diff mbox series

[5.10.y-cip,1/7] tty: serial: sh-sci: Fix TE setting on SCI IP

Message ID 20230605110512.111017-2-biju.das.jz@bp.renesas.com (mailing list archive)
State Accepted
Headers show
Series Add SCI support for RZ/G2L alike SoCs | expand

Commit Message

Biju Das June 5, 2023, 11:05 a.m. UTC 
commit 1707ce2d1e4d701db28ba2250d9d72dcf762babc upstream.

As per the RZ/G2L users hardware manual (Rev.1.20 Sep, 2022), section
23.3.7 Serial Data Transmission (Asynchronous Mode) it is mentioned
that the TE (transmit enable) must be set after setting TIE (transmit
interrupt enable) or these 2 bits are set to 1 simultaneously by a
single instruction. So set these 2 bits in single instruction.

Signed-off-by: Biju Das <biju.das.jz@bp.renesas.com>
Link: https://lore.kernel.org/r/20230412145053.114847-4-biju.das.jz@bp.renesas.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Biju Das <biju.das.jz@bp.renesas.com>
---
 drivers/tty/serial/sh-sci.c | 19 +++++++++++++++++--
 1 file changed, 17 insertions(+), 2 deletions(-)
diff mbox series

Patch

diff --git a/drivers/tty/serial/sh-sci.c b/drivers/tty/serial/sh-sci.c
index 6720c165523a..fe29b05f42c4 100644
--- a/drivers/tty/serial/sh-sci.c
+++ b/drivers/tty/serial/sh-sci.c
@@ -596,6 +596,15 @@  static void sci_start_tx(struct uart_port *port)
 	if (!s->chan_tx || port->type == PORT_SCIFA || port->type == PORT_SCIFB) {
 		/* Set TIE (Transmit Interrupt Enable) bit in SCSCR */
 		ctrl = serial_port_in(port, SCSCR);
+
+		/*
+		 * For SCI, TE (transmit enable) must be set after setting TIE
+		 * (transmit interrupt enable) or in the same instruction to start
+		 * the transmit process.
+		 */
+		if (port->type == PORT_SCI)
+			ctrl |= SCSCR_TE;
+
 		serial_port_out(port, SCSCR, ctrl | SCSCR_TIE);
 	}
 }
@@ -2618,8 +2627,14 @@  static void sci_set_termios(struct uart_port *port, struct ktermios *termios,
 		sci_set_mctrl(port, port->mctrl);
 	}
 
-	scr_val |= SCSCR_RE | SCSCR_TE |
-		   (s->cfg->scscr & ~(SCSCR_CKE1 | SCSCR_CKE0));
+	/*
+	 * For SCI, TE (transmit enable) must be set after setting TIE
+	 * (transmit interrupt enable) or in the same instruction to
+	 * start the transmitting process. So skip setting TE here for SCI.
+	 */
+	if (port->type != PORT_SCI)
+		scr_val |= SCSCR_TE;
+	scr_val |= SCSCR_RE | (s->cfg->scscr & ~(SCSCR_CKE1 | SCSCR_CKE0));
 	serial_port_out(port, SCSCR, scr_val | s->hscif_tot);
 	if ((srr + 1 == 5) &&
 	    (port->type == PORT_SCIFA || port->type == PORT_SCIFB)) {