tjh.dev
-12
Documentation/ABI/testing/sysfs-devices-deferred_probe
-12
Documentation/ABI/testing/sysfs-devices-deferred_probe
···
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What: /sys/devices/.../deferred_probe
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Date: August 2016
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Contact: Ben Hutchings <ben.hutchings@codethink.co.uk>
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Description:
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The /sys/devices/.../deferred_probe attribute is
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present for all devices. If a driver detects during
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probing a device that a related device is not yet
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ready, it may defer probing of the first device. The
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kernel will retry probing the first device after any
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other device is successfully probed. This attribute
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reads as 1 if probing of this device is currently
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deferred, or 0 otherwise.
-2
drivers/base/base.h
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drivers/base/base.h
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extern struct kset *devices_kset;
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extern void devices_kset_move_last(struct device *dev);
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extern struct device_attribute dev_attr_deferred_probe;
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146
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#if defined(CONFIG_MODULES) && defined(CONFIG_SYSFS)
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extern void module_add_driver(struct module *mod, struct device_driver *drv);
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extern void module_remove_driver(struct device_driver *drv);
-7
drivers/base/core.c
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drivers/base/core.c
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goto err_remove_dev_groups;
1061
1061
}
1062
1062
1063
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error = device_create_file(dev, &dev_attr_deferred_probe);
1064
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if (error)
1065
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goto err_remove_online;
1066
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1067
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return 0;
1068
1064
1069
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err_remove_online:
1070
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device_remove_file(dev, &dev_attr_online);
1071
1065
err_remove_dev_groups:
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device_remove_groups(dev, dev->groups);
1073
1067
err_remove_type_groups:
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1085
struct class *class = dev->class;
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const struct device_type *type = dev->type;
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1087
1082
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device_remove_file(dev, &dev_attr_deferred_probe);
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device_remove_file(dev, &dev_attr_online);
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device_remove_groups(dev, dev->groups);
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1090
-13
drivers/base/dd.c
-13
drivers/base/dd.c
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static LIST_HEAD(deferred_probe_active_list);
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static atomic_t deferred_trigger_count = ATOMIC_INIT(0);
55
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56
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static ssize_t deferred_probe_show(struct device *dev,
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struct device_attribute *attr, char *buf)
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{
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bool value;
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mutex_lock(&deferred_probe_mutex);
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value = !list_empty(&dev->p->deferred_probe);
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mutex_unlock(&deferred_probe_mutex);
64
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return sprintf(buf, "%d\n", value);
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}
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DEVICE_ATTR_RO(deferred_probe);
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69
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/*
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* In some cases, like suspend to RAM or hibernation, It might be reasonable
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* to prohibit probing of devices as it could be unsafe.