serial: sh-sci: fix hardware RX trigger level setting

1. Do not set the RX trigger level for software timeout devices on reset;
there is no timeout by default, and data will rot.
2. Do set the RX trigger level for hardware timeout devices when set
via sysfs attribute.

Fixes SCIFA-type serial consoles.

Signed-off-by: Ulrich Hecht <ulrich.hecht+renesas@gmail.com>
Tested-by: Geert Uytterhoeven <geert+renesas@glider.be>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

1 files changed, 9 insertions, 2 deletions

diff --git a/drivers/tty/serial/sh-sci.c b/drivers/tty/serial/sh-sci.c
index f95a56ca936e..9a47cc4f16a2 100644
--- a/drivers/tty/serial/sh-sci.c
+++ b/drivers/tty/serial/sh-sci.c
@@ -1076,8 +1076,11 @@ static ssize_t rx_trigger_store(struct device *dev,
 
         if (kstrtol(buf, 0, &r) == -EINVAL)
                 return -EINVAL;
+
         sci->rx_trigger = scif_set_rtrg(port, r);
-        scif_set_rtrg(port, 1);
+        if (port->type == PORT_SCIFA || port->type == PORT_SCIFB)
+                scif_set_rtrg(port, 1);
+
         return count;
 }
 
@@ -2179,7 +2182,11 @@ static void sci_reset(struct uart_port *port)
                         setup_timer(&s->rx_fifo_timer, rx_fifo_timer_fn,
                                     (unsigned long)s);
                 } else {
-                        scif_set_rtrg(port, s->rx_trigger);
+                        if (port->type == PORT_SCIFA ||
+                            port->type == PORT_SCIFB)
+                                scif_set_rtrg(port, 1);
+                        else
+                                scif_set_rtrg(port, s->rx_trigger);
                 }
         }
 }