[patch] Add insmod option to force the use of the backup timer.

The test which automatically enables the backup timer on some HP
machines doesn't trigger on other hardware which needs the backup
timer too.

This patch add a way to enable it manually (8250.use_backup_timer=1)
to deal with these machines.

Signed-off-by: Gerd Hoffmann <kraxel@xxxxxxx>
Cc: Alex Williamson <alex.williamson@xxxxxx>
Cc: Kevin Stansell <kstansel@xxxxxxxxxx>
---
drivers/serial/8250.c | 7 +++++--
1 file changed, 5 insertions(+), 2 deletions(-)

Index: vanilla-2.6.21-rc2/drivers/serial/8250.c
===================================================================
--- vanilla-2.6.21-rc2.orig/drivers/serial/8250.c
+++ vanilla-2.6.21-rc2/drivers/serial/8250.c
@@ -52,8 +52,8 @@
* is unsafe when used on edge-triggered interrupts.
*/
static unsigned int share_irqs = SERIAL8250_SHARE_IRQS;
-
static unsigned int nr_uarts = CONFIG_SERIAL_8250_RUNTIME_UARTS;
+static unsigned int use_backup_timer;

/*
* Debugging.
@@ -1729,7 +1729,7 @@ static int serial8250_startup(struct uar
* If the interrupt is not reasserted, setup a timer to
* kick the UART on a regular basis.
*/
- if (iir & UART_IIR_NO_INT) {
+ if (iir & UART_IIR_NO_INT || use_backup_timer) {
pr_debug("ttyS%d - using backup timer\n", port->line);
up->timer.function = serial8250_backup_timeout;
up->timer.data = (unsigned long)up;
@@ -2805,6 +2805,9 @@ module_param(share_irqs, uint, 0644);
MODULE_PARM_DESC(share_irqs, "Share IRQs with other non-8250/16x50 devices"
" (unsafe)");

+module_param(use_backup_timer, uint, 0644);
+MODULE_PARM_DESC(use_backup_timer, "use backup timer");
+
module_param(nr_uarts, uint, 0644);
MODULE_PARM_DESC(nr_uarts, "Maximum number of UARTs supported. (1-" __MODULE_STRING(CONFIG_SERIAL_8250_NR_UARTS) ")");


--
Gerd Hoffmann <kraxel@xxxxxxx>

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