Subject: [PATCH 2/2] atmel_serial: Implement flush_buffer() hook

Avoid dumping garbage to the serial port when the tty is flushed. This
tends to happen when rebooting from a serial console.

Signed-off-by: Haavard Skinnemoen <haavard.skinnemoen@atmel.com>
Acked-by: Alan Cox <alan@redhat.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 15 insertions, 0 deletions

diff --git a/drivers/serial/atmel_serial.c b/drivers/serial/atmel_serial.c
index 6aeef22bd203..c17fcd6085f3 100644
--- a/drivers/serial/atmel_serial.c
+++ b/drivers/serial/atmel_serial.c
@@ -956,6 +956,20 @@ static void atmel_shutdown(struct uart_port *port)
 }
 
 /*
+ * Flush any TX data submitted for DMA. Called when the TX circular
+ * buffer is reset.
+ */
+static void atmel_flush_buffer(struct uart_port *port)
+{
+        struct atmel_uart_port *atmel_port = to_atmel_uart_port(port);
+
+        if (atmel_use_dma_tx(port)) {
+                UART_PUT_TCR(port, 0);
+                atmel_port->pdc_tx.ofs = 0;
+        }
+}
+
+/*
  * Power / Clock management.
  */
 static void atmel_serial_pm(struct uart_port *port, unsigned int state,
@@ -1189,6 +1203,7 @@ static struct uart_ops atmel_pops = {
         .break_ctl      = atmel_break_ctl,
         .startup        = atmel_startup,
         .shutdown       = atmel_shutdown,
+        .flush_buffer   = atmel_flush_buffer,
         .set_termios    = atmel_set_termios,
         .type           = atmel_type,
         .release_port   = atmel_release_port,