Gitweb:     
http://git.kernel.org/git/?p=linux/kernel/git/torvalds/linux-2.6.git;a=commit;h=da4249c99fd59c4e224e4f9acaf07669d205bb1d
Commit:     da4249c99fd59c4e224e4f9acaf07669d205bb1d
Parent:     9d9d50bb2efb50594abfc3941a5504b62c514ebd
Author:     Dmitry Torokhov <[EMAIL PROTECTED]>
AuthorDate: Thu Jun 28 00:46:56 2007 -0400
Committer:  Dmitry Torokhov <[EMAIL PROTECTED]>
CommitDate: Thu Jun 28 00:46:56 2007 -0400

    Input: atkbd - throttle LED switching
    
    On some boxes keyboard controllers are too slow to withstand
    continuous flow of requests to turn keyboard LEDs on and off
    and start losing some keypresses or even all of them.
    
    Delay executing of LED switching request if we had another one
    within 50 ms thus easing load on the controller.
    
    Signed-off-by: Dmitry Torokhov <[EMAIL PROTECTED]>
---
 drivers/input/keyboard/atkbd.c |   40 ++++++++++++++++++++++++++--------------
 1 files changed, 26 insertions(+), 14 deletions(-)

diff --git a/drivers/input/keyboard/atkbd.c b/drivers/input/keyboard/atkbd.c
index be1fe46..9e80012 100644
--- a/drivers/input/keyboard/atkbd.c
+++ b/drivers/input/keyboard/atkbd.c
@@ -219,7 +219,8 @@ struct atkbd {
        unsigned long time;
        unsigned long err_count;
 
-       struct work_struct event_work;
+       struct delayed_work event_work;
+       unsigned long event_jiffies;
        struct mutex event_mutex;
        unsigned long event_mask;
 };
@@ -565,7 +566,7 @@ static int atkbd_set_leds(struct atkbd *atkbd)
 
 static void atkbd_event_work(struct work_struct *work)
 {
-       struct atkbd *atkbd = container_of(work, struct atkbd, event_work);
+       struct atkbd *atkbd = container_of(work, struct atkbd, event_work.work);
 
        mutex_lock(&atkbd->event_mutex);
 
@@ -579,12 +580,30 @@ static void atkbd_event_work(struct work_struct *work)
 }
 
 /*
+ * Schedule switch for execution. We need to throttle requests,
+ * otherwise keyboard may become unresponsive.
+ */
+static void atkbd_schedule_event_work(struct atkbd *atkbd, int event_bit)
+{
+       unsigned long delay = msecs_to_jiffies(50);
+
+       if (time_after(jiffies, atkbd->event_jiffies + delay))
+               delay = 0;
+
+       atkbd->event_jiffies = jiffies;
+       set_bit(event_bit, &atkbd->event_mask);
+       wmb();
+       schedule_delayed_work(&atkbd->event_work, delay);
+}
+
+/*
  * Event callback from the input module. Events that change the state of
  * the hardware are processed here. If action can not be performed in
  * interrupt context it is offloaded to atkbd_event_work.
  */
 
-static int atkbd_event(struct input_dev *dev, unsigned int type, unsigned int 
code, int value)
+static int atkbd_event(struct input_dev *dev,
+                       unsigned int type, unsigned int code, int value)
 {
        struct atkbd *atkbd = input_get_drvdata(dev);
 
@@ -594,19 +613,12 @@ static int atkbd_event(struct input_dev *dev, unsigned 
int type, unsigned int co
        switch (type) {
 
                case EV_LED:
-                       set_bit(ATKBD_LED_EVENT_BIT, &atkbd->event_mask);
-                       wmb();
-                       schedule_work(&atkbd->event_work);
+                       atkbd_schedule_event_work(atkbd, ATKBD_LED_EVENT_BIT);
                        return 0;
 
                case EV_REP:
-
-                       if (!atkbd->softrepeat) {
-                               set_bit(ATKBD_REP_EVENT_BIT, 
&atkbd->event_mask);
-                               wmb();
-                               schedule_work(&atkbd->event_work);
-                       }
-
+                       if (!atkbd->softrepeat)
+                               atkbd_schedule_event_work(atkbd, 
ATKBD_REP_EVENT_BIT);
                        return 0;
        }
 
@@ -940,7 +952,7 @@ static int atkbd_connect(struct serio *serio, struct 
serio_driver *drv)
 
        atkbd->dev = dev;
        ps2_init(&atkbd->ps2dev, serio);
-       INIT_WORK(&atkbd->event_work, atkbd_event_work);
+       INIT_DELAYED_WORK(&atkbd->event_work, atkbd_event_work);
        mutex_init(&atkbd->event_mutex);
 
        switch (serio->id.type) {
-
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