serial: sh-sci: Stop transfers in sci_shutdown()
Make sure the transmitter and receiver are stopped when shutting down
the port, and related interrupts are disabled.
Without this:
- New input data may be received into the RX FIFO, possibly
triggering a new RX DMA completion,
- Transfers will still be enabled on a subsequent startup of the UART,
before the UART's FIFOs have been reset, causing reading of stale
data.
Inspired by a patch in the BSP by Koji Matsuoka
<koji.matsuoka.xm@renesas.com>.
Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
diff --git a/drivers/tty/serial/sh-sci.c b/drivers/tty/serial/sh-sci.c
index 432d9ac..d86eee3 100644
--- a/drivers/tty/serial/sh-sci.c
+++ b/drivers/tty/serial/sh-sci.c
@@ -1989,6 +1989,7 @@
{
struct sci_port *s = to_sci_port(port);
unsigned long flags;
+ u16 scr;
dev_dbg(port->dev, "%s(%d)\n", __func__, port->line);
@@ -1998,6 +1999,9 @@
spin_lock_irqsave(&port->lock, flags);
sci_stop_rx(port);
sci_stop_tx(port);
+ /* Stop RX and TX, disable related interrupts, keep clock source */
+ scr = serial_port_in(port, SCSCR);
+ serial_port_out(port, SCSCR, scr & (SCSCR_CKE1 | SCSCR_CKE0));
spin_unlock_irqrestore(&port->lock, flags);
#ifdef CONFIG_SERIAL_SH_SCI_DMA