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
<[email protected]>.
Signed-off-by: Geert Uytterhoeven <[email protected]>
---
v2:
- Do not clear clock source bits, since the serial console relies on
them, as reported by Shimoda-san.
v1 was 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 | 5 +++++
1 file changed, 5 insertions(+)
diff --git a/drivers/tty/serial/sh-sci.c b/drivers/tty/serial/sh-sci.c
index d6ba90c572f7475c..eecace576c3b758f 100644
--- a/drivers/tty/serial/sh-sci.c
+++ b/drivers/tty/serial/sh-sci.c
@@ -1890,12 +1890,17 @@ static void sci_shutdown(struct uart_port *port)
{
struct sci_port *s = to_sci_port(port);
unsigned long flags;
+ u16 scr;
dev_dbg(port->dev, "%s(%d)\n", __func__, port->line);
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
--
1.9.1
