From 4a9bde9b8ab55a2bb51b57cad215a97bcf80bae2 Mon Sep 17 00:00:00 2001
From: Stefan Richter <stefanr@s5r6.in-berlin.de>
Date: Sat, 20 Feb 2010 22:24:43 +0100
Subject: firewire: get_cycle_timer optimization and cleanup

ohci:  Break out of the retry loop if too many attempts were necessary.
This may theoretically happen if the chip is fatally defective or if the
get_cycle_timer ioctl was performed after a CardBus controller was
ejected.

Also micro-optimize the loop by re-using the last two register reads in
the next iteration, remove a questionable inline keyword, and shuffle a
comment around.

core:  ioctl_get_cycle_timer() is always called with interrupts on,
therefore local_irq_save() can be replaced by local_irq_disable().
Disabled local IRQs imply disabled preemption, hence preempt_disable()
can be removed.

Signed-off-by: Stefan Richter <stefanr@s5r6.in-berlin.de>
---
 drivers/firewire/core-cdev.c | 16 +++++++---------
 1 file changed, 7 insertions(+), 9 deletions(-)

(limited to 'drivers/firewire/core-cdev.c')

diff --git a/drivers/firewire/core-cdev.c b/drivers/firewire/core-cdev.c
index e6d63849e78e..ecd0a4d81abf 100644
--- a/drivers/firewire/core-cdev.c
+++ b/drivers/firewire/core-cdev.c
@@ -25,6 +25,7 @@
 #include <linux/firewire.h>
 #include <linux/firewire-cdev.h>
 #include <linux/idr.h>
+#include <linux/irqflags.h>
 #include <linux/jiffies.h>
 #include <linux/kernel.h>
 #include <linux/kref.h>
@@ -32,7 +33,6 @@
 #include <linux/module.h>
 #include <linux/mutex.h>
 #include <linux/poll.h>
-#include <linux/preempt.h>
 #include <linux/sched.h>
 #include <linux/spinlock.h>
 #include <linux/time.h>
@@ -1013,21 +1013,19 @@ static int ioctl_get_cycle_timer(struct client *client, void *buffer)
 {
 	struct fw_cdev_get_cycle_timer *request = buffer;
 	struct fw_card *card = client->device->card;
-	unsigned long long bus_time;
 	struct timeval tv;
-	unsigned long flags;
+	u32 cycle_time;
 
-	preempt_disable();
-	local_irq_save(flags);
+	local_irq_disable();
 
-	bus_time = card->driver->get_bus_time(card);
+	cycle_time = card->driver->get_bus_time(card);
 	do_gettimeofday(&tv);
 
-	local_irq_restore(flags);
-	preempt_enable();
+	local_irq_enable();
 
 	request->local_time = tv.tv_sec * 1000000ULL + tv.tv_usec;
-	request->cycle_timer = bus_time & 0xffffffff;
+	request->cycle_timer = cycle_time;
+
 	return 0;
 }
 
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