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path: root/drivers/tty/serial/8250/8250_early.c
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Diffstat (limited to 'drivers/tty/serial/8250/8250_early.c')
-rw-r--r--drivers/tty/serial/8250/8250_early.c13
1 files changed, 9 insertions, 4 deletions
diff --git a/drivers/tty/serial/8250/8250_early.c b/drivers/tty/serial/8250/8250_early.c
index 4858b8a99d3b..c31a22b4f845 100644
--- a/drivers/tty/serial/8250/8250_early.c
+++ b/drivers/tty/serial/8250/8250_early.c
@@ -93,15 +93,18 @@ static void __init early_serial8250_write(struct console *console,
struct uart_port *port = &early_device->port;
unsigned int ier;
- /* Save the IER and disable interrupts */
+ /* Save the IER and disable interrupts preserving the UUE bit */
ier = serial8250_early_in(port, UART_IER);
- serial8250_early_out(port, UART_IER, 0);
+ if (ier)
+ serial8250_early_out(port, UART_IER, ier & UART_IER_UUE);
uart_console_write(port, s, count, serial_putc);
/* Wait for transmitter to become empty and restore the IER */
wait_for_xmitr(port);
- serial8250_early_out(port, UART_IER, ier);
+
+ if (ier)
+ serial8250_early_out(port, UART_IER, ier);
}
static unsigned int __init probe_baud(struct uart_port *port)
@@ -124,9 +127,11 @@ static void __init init_port(struct earlycon_device *device)
struct uart_port *port = &device->port;
unsigned int divisor;
unsigned char c;
+ unsigned int ier;
serial8250_early_out(port, UART_LCR, 0x3); /* 8n1 */
- serial8250_early_out(port, UART_IER, 0); /* no interrupt */
+ ier = serial8250_early_in(port, UART_IER);
+ serial8250_early_out(port, UART_IER, ier & UART_IER_UUE); /* no interrupt */
serial8250_early_out(port, UART_FCR, 0); /* no fifo */
serial8250_early_out(port, UART_MCR, 0x3); /* DTR + RTS */