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@xxxxxxxxxxx>.
Signed-off-by: Geert Uytterhoeven <geert+renesas@xxxxxxxxx>
---
Extracted from "[PATCH/RFC v3 0/4] serial: sh-sci: Add DT DMA support".
The issues with the serial console seen before on r8a7740/armadillo and
sh73a0/kzm9g seem to be gone.
Changes after resurrection:
- Write zero to also disable related interrupts, as suggested by
Laurent Pinchart,
- Enhanced patch description.
---
drivers/tty/serial/sh-sci.c | 2 ++
1 file changed, 2 insertions(+)
diff --git a/drivers/tty/serial/sh-sci.c b/drivers/tty/serial/sh-sci.c
index d6ba90c572f7475c..4d2f916f45277e20 100644
--- a/drivers/tty/serial/sh-sci.c
+++ b/drivers/tty/serial/sh-sci.c
@@ -1896,6 +1896,8 @@ static void sci_shutdown(struct uart_port *port)
spin_lock_irqsave(&port->lock, flags);
sci_stop_rx(port);
sci_stop_tx(port);
+ /* Stop RX and TX, disable related interrupts */
+ serial_port_out(port, SCSCR, 0);
spin_unlock_irqrestore(&port->lock, flags);
#ifdef CONFIG_SERIAL_SH_SCI_DMA
--
1.9.1
