linux-kernel - [patch] serial: add parameter to force skipping the test for the TXEN bug

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Message-ID: <20090420180549.335552bb@dhcp-100-2-144.bos.redhat.com>
Date:	Mon, 20 Apr 2009 18:05:49 -0400
From:	Chuck Ebbert <cebbert@...hat.com>
To:	Andrew Morton <akpm@...ux-foundation.org>
Cc:	Alan Cox <alan@...rguk.ukuu.org.uk>, linux-kernel@...r.kernel.org
Subject: [patch] serial: add parameter to force skipping the test for the
 TXEN bug

serial: add parameter to force skipping the test for the TXEN bug

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@...hat.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");
--
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