133 lines
4.4 KiB
Diff
133 lines
4.4 KiB
Diff
Bugzilla: 1093171
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Upstream-status: Queued for 3.16
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From ee515e61a002b4d571407173ac8bbadadc114cf0 Mon Sep 17 00:00:00 2001
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From: Hans de Goede <hdegoede@redhat.com>
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Date: Mon, 2 Jun 2014 17:41:08 +0200
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Subject: [PATCH 11/14] backlight: Add backlight device (un)registration
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notification
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Some firmware drivers, ie acpi-video want to get themselves out of the
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way (in some cases) when their also is a raw backlight device available.
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Due to module loading ordering being unknown, acpi-video cannot be certain
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that the backlight_device_registered(BACKLIGHT_RAW) it does for this is
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the final verdict wrt there being a BACKLIGHT_RAW device.
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By adding notification acpi-video can listen for backlight devices showing
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up after it has loaded, and unregister its backlight device if desired.
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Signed-off-by: Hans de Goede <hdegoede@redhat.com>
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---
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drivers/video/backlight/backlight.c | 40 +++++++++++++++++++++++++++++++++++++
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include/linux/backlight.h | 7 +++++++
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2 files changed, 47 insertions(+)
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diff --git a/drivers/video/backlight/backlight.c b/drivers/video/backlight/backlight.c
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index bd2172c2d650..428089009cd5 100644
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--- a/drivers/video/backlight/backlight.c
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+++ b/drivers/video/backlight/backlight.c
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@@ -23,6 +23,7 @@
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static struct list_head backlight_dev_list;
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static struct mutex backlight_dev_list_mutex;
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+static struct blocking_notifier_head backlight_notifier;
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static const char *const backlight_types[] = {
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[BACKLIGHT_RAW] = "raw",
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@@ -370,6 +371,9 @@ struct backlight_device *backlight_device_register(const char *name,
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list_add(&new_bd->entry, &backlight_dev_list);
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mutex_unlock(&backlight_dev_list_mutex);
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+ blocking_notifier_call_chain(&backlight_notifier,
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+ BACKLIGHT_REGISTERED, new_bd);
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+
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return new_bd;
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}
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EXPORT_SYMBOL(backlight_device_register);
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@@ -413,6 +417,10 @@ void backlight_device_unregister(struct backlight_device *bd)
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pmac_backlight = NULL;
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mutex_unlock(&pmac_backlight_mutex);
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#endif
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+
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+ blocking_notifier_call_chain(&backlight_notifier,
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+ BACKLIGHT_UNREGISTERED, bd);
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+
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mutex_lock(&bd->ops_lock);
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bd->ops = NULL;
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mutex_unlock(&bd->ops_lock);
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@@ -438,6 +446,36 @@ static int devm_backlight_device_match(struct device *dev, void *res,
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}
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/**
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+ * backlight_register_notifier - get notified of backlight (un)registration
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+ * @nb: notifier block with the notifier to call on backlight (un)registration
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+ *
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+ * @return 0 on success, otherwise a negative error code
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+ *
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+ * Register a notifier to get notified when backlight devices get registered
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+ * or unregistered.
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+ */
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+int backlight_register_notifier(struct notifier_block *nb)
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+{
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+ return blocking_notifier_chain_register(&backlight_notifier, nb);
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+}
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+EXPORT_SYMBOL(backlight_register_notifier);
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+
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+/**
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+ * backlight_unregister_notifier - unregister a backlight notifier
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+ * @nb: notifier block to unregister
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+ *
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+ * @return 0 on success, otherwise a negative error code
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+ *
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+ * Register a notifier to get notified when backlight devices get registered
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+ * or unregistered.
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+ */
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+int backlight_unregister_notifier(struct notifier_block *nb)
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+{
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+ return blocking_notifier_chain_unregister(&backlight_notifier, nb);
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+}
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+EXPORT_SYMBOL(backlight_unregister_notifier);
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+
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+/**
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* devm_backlight_device_register - resource managed backlight_device_register()
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* @dev: the device to register
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* @name: the name of the device
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@@ -544,6 +582,8 @@ static int __init backlight_class_init(void)
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backlight_class->pm = &backlight_class_dev_pm_ops;
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INIT_LIST_HEAD(&backlight_dev_list);
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mutex_init(&backlight_dev_list_mutex);
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+ BLOCKING_INIT_NOTIFIER_HEAD(&backlight_notifier);
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+
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return 0;
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}
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diff --git a/include/linux/backlight.h b/include/linux/backlight.h
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index 72647429adf6..adb14a8616df 100644
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--- a/include/linux/backlight.h
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+++ b/include/linux/backlight.h
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@@ -40,6 +40,11 @@ enum backlight_type {
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BACKLIGHT_TYPE_MAX,
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};
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+enum backlight_notification {
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+ BACKLIGHT_REGISTERED,
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+ BACKLIGHT_UNREGISTERED,
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+};
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+
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struct backlight_device;
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struct fb_info;
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@@ -133,6 +138,8 @@ extern void devm_backlight_device_unregister(struct device *dev,
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extern void backlight_force_update(struct backlight_device *bd,
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enum backlight_update_reason reason);
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extern bool backlight_device_registered(enum backlight_type type);
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+extern int backlight_register_notifier(struct notifier_block *nb);
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+extern int backlight_unregister_notifier(struct notifier_block *nb);
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#define to_backlight_device(obj) container_of(obj, struct backlight_device, dev)
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--
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1.9.0
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