Allow users to force skipping the TXEN test at init time. Applies
to all serial ports. Intended for debugging only.

Signed-off-by: Chuck Ebbert <cebbert@redhat.com>

Index: linux-2.6.29.noarch/drivers/serial/8250.c
===================================================================
--- linux-2.6.29.noarch.orig/drivers/serial/8250.c
+++ linux-2.6.29.noarch/drivers/serial/8250.c
@@ -67,6 +67,8 @@ static int serial_index(struct uart_port
 	return (serial8250_reg.minor - 64) + port->line;
 }
 
+static unsigned int skip_txen_test; /* force skip of txen test at init time */
+
 /*
  * Debugging.
  */
@@ -2097,7 +2099,7 @@ static int serial8250_startup(struct uar
 	   is variable. So, let's just don't test if we receive
 	   TX irq. This way, we'll never enable UART_BUG_TXEN.
 	 */
-	if (up->port.flags & UPF_NO_TXEN_TEST)
+	if (skip_txen_test || up->port.flags & UPF_NO_TXEN_TEST)
 		goto dont_test_tx_en;
 
 	/*
@@ -3245,6 +3247,9 @@ MODULE_PARM_DESC(share_irqs, "Share IRQs
 module_param(nr_uarts, uint, 0644);
 MODULE_PARM_DESC(nr_uarts, "Maximum number of UARTs supported. (1-" __MODULE_STRING(CONFIG_SERIAL_8250_NR_UARTS) ")");
 
+module_param(skip_txen_test, uint, 0644);
+MODULE_PARM_DESC(skip_txen_test, "Skip checking for the TXEN bug at init time");
+
 #ifdef CONFIG_SERIAL_8250_RSA
 module_param_array(probe_rsa, ulong, &probe_rsa_count, 0444);
 MODULE_PARM_DESC(probe_rsa, "Probe I/O ports for RSA");