Hi!

> > > > > Some LED controllers may come with an internal HW triggering mechanism
> > > > > for the LED and an ability to switch between user control of the LED,
> > > > > or the internal control. One such example is AXP20X PMIC, that allows
> > > > > wither for user control of the LED, or for internal control based on
> > > > > the state of the battery charger.
> > > > > 
> > > > > Add support for registering per-LED device trigger.
> > > > > 
> > > > > Names of private triggers need to be globally unique, but may clash
> > > > > with other private triggers. This is enforced during trigger
> > > > > registration. Developers can register private triggers just like
> > > > > the normal triggers, by setting private_led to a classdev
> > > > > of the LED the trigger is associated with.
> > > > 
> > > > What about this? Should address Marek's concerns about resource use...
> > > 
> > > What concerns? Marek's concerns seem to be about case where we register
> > > a trigger for (each led * self-working configuration) which I admit
> > > can be quite a lot of triggers if there are many functions. But that's
> > > not my proposal.
> > > 
> > > My proposal is to only register on trigger per LED at most. So on my
> > > system that's 1 extra trigger and on Marek's system that'd be 48 new
> > > triggers. Neither seems like a meaningful problem from resource
> > > use perspective.
> > 
> > So.. 48 triggers on Marek's systems means I'll not apply your patch.
> > 
> > Please take a look at my version, it is as simple and avoids that
> > problem.
> 
> I would, but I don't see your version linked or mentioned in this
> thread.

Ah! Sorry about that. Here it is. (I verified it compiles in the
meantime).

Best regards,
                                                                Pavel

diff --git a/drivers/leds/led-triggers.c b/drivers/leds/led-triggers.c
index 79e30d2cb7a5..e8333675959c 100644
--- a/drivers/leds/led-triggers.c
+++ b/drivers/leds/led-triggers.c
@@ -27,6 +27,12 @@ LIST_HEAD(trigger_list);
 
  /* Used by LED Class */
 
+static inline bool
+trigger_relevant(struct led_classdev *led_cdev, struct led_trigger *trig)
+{
+       return !trig->trigger_type || trig->trigger_type == 
led_cdev->trigger_type;
+}
+
 ssize_t led_trigger_write(struct file *filp, struct kobject *kobj,
                          struct bin_attribute *bin_attr, char *buf,
                          loff_t pos, size_t count)
@@ -50,7 +56,8 @@ ssize_t led_trigger_write(struct file *filp, struct kobject 
*kobj,
 
        down_read(&triggers_list_lock);
        list_for_each_entry(trig, &trigger_list, next_trig) {
-               if (sysfs_streq(buf, trig->name)) {
+               if (sysfs_streq(buf, trig->name) &&
+                   trigger_relevant(led_cdev, trig)) {
                        down_write(&led_cdev->trigger_lock);
                        led_trigger_set(led_cdev, trig);
                        up_write(&led_cdev->trigger_lock);
@@ -96,6 +103,9 @@ static int led_trigger_format(char *buf, size_t size,
                bool hit = led_cdev->trigger &&
                        !strcmp(led_cdev->trigger->name, trig->name);
 
+               if (!trigger_relevant(led_cdev, trig))
+                       continue;
+
                len += led_trigger_snprintf(buf + len, size - len,
                                            " %s%s%s", hit ? "[" : "",
                                            trig->name, hit ? "]" : "");
@@ -243,7 +253,8 @@ void led_trigger_set_default(struct led_classdev *led_cdev)
        down_read(&triggers_list_lock);
        down_write(&led_cdev->trigger_lock);
        list_for_each_entry(trig, &trigger_list, next_trig) {
-               if (!strcmp(led_cdev->default_trigger, trig->name)) {
+               if (!strcmp(led_cdev->default_trigger, trig->name) &&
+                   trigger_relevant(led_cdev, trig)) {
                        led_cdev->flags |= LED_INIT_DEFAULT_TRIGGER;
                        led_trigger_set(led_cdev, trig);
                        break;
@@ -280,7 +291,8 @@ int led_trigger_register(struct led_trigger *trig)
        down_write(&triggers_list_lock);
        /* Make sure the trigger's name isn't already in use */
        list_for_each_entry(_trig, &trigger_list, next_trig) {
-               if (!strcmp(_trig->name, trig->name)) {
+               if (!strcmp(_trig->name, trig->name) &&
+                   (!_trig->private_led || _trig->private_led == 
trig->private_led)) {
                        up_write(&triggers_list_lock);
                        return -EEXIST;
                }
diff --git a/include/linux/leds.h b/include/linux/leds.h
index 2451962d1ec5..cba52714558f 100644
--- a/include/linux/leds.h
+++ b/include/linux/leds.h
@@ -57,6 +57,10 @@ struct led_init_data {
        bool devname_mandatory;
 };
 
+struct led_hw_trigger_type {
+       int dummy;
+}
+
 struct led_classdev {
        const char              *name;
        enum led_brightness      brightness;
@@ -150,6 +154,8 @@ struct led_classdev {
 
        /* Ensures consistent access to the LED Flash Class device */
        struct mutex            led_access;
+
+       struct led_hw_trigger_type *trigger_type;
 };
 
 /**
@@ -345,6 +351,9 @@ struct led_trigger {
        int             (*activate)(struct led_classdev *led_cdev);
        void            (*deactivate)(struct led_classdev *led_cdev);
 
+       /* LED-private triggers have this set. */
+       struct led_hw_trigger_type *trigger_type;
+
        /* LEDs under control by this trigger (for simple triggers) */
        rwlock_t          leddev_list_lock;
        struct list_head  led_cdevs;

-- 
(english) http://www.livejournal.com/~pavelmachek
(cesky, pictures) 
http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html

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