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>

diff --git a/drivers/serial/atmel_serial.c b/drivers/serial/atmel_serial.c
index 6aeef22bd2039ea41fbfc2cc6062dbb4c03cd83e..c17fcd6085f39a5cdf21e85423a655433ac2d902 100644 (file)
--- a/drivers/serial/atmel_serial.c
+++ b/drivers/serial/atmel_serial.c
@@ -955,6 +955,20 @@ static void atmel_shutdown(struct uart_port *port)
                atmel_close_hook(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.
  */
@@ -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,