[PATCH v6 20/22] driver core: Allow deferring probes until late init
From: Tomeu Vizoso <hidden>
Date: 2015-09-21 14:04:16
Also in:
linux-acpi, linux-devicetree, lkml
Subsystem:
driver core, kobjects, debugfs and sysfs, the rest · Maintainers:
Greg Kroah-Hartman, "Rafael J. Wysocki", Danilo Krummrich, Linus Torvalds
Add a field to struct device that instructs the device-driver core to defer the probe of this device until the late_initcall level. By letting all built-in drivers to register before starting to probe, we can avoid any deferred probes by probing dependencies on demand. Signed-off-by: Tomeu Vizoso <redacted> --- Changes in v4: - Add Kconfig DELAY_DEVICE_PROBES to allow disabling delayed probing in machines with initcalls that depend on devices probing at a given time. drivers/base/Kconfig | 18 ++++++++++++++++++ drivers/base/dd.c | 7 +++++++ include/linux/device.h | 2 ++ 3 files changed, 27 insertions(+)
diff --git a/drivers/base/Kconfig b/drivers/base/Kconfig
index 98504ec99c7d..44b5d33b1f49 100644
--- a/drivers/base/Kconfig
+++ b/drivers/base/Kconfig@@ -324,4 +324,22 @@ config CMA_ALIGNMENT endif +config DELAY_DEVICE_PROBES + bool "Allow delaying the probe of some devices" + default y + help + Devices can be matched to a driver and probed from the moment they + are registered, but early during boot their probes are likely to be + deferred because some dependency isn't available yet because most + drivers haven't been registered yet. + + Enabling this option allows the device registration code to delay the + probing of a specific device until device_initcall_sync, when all + built-in drivers have been registered already. + + In some platforms there may be implicit assumptions about when some + devices are probed, so enabling this option could cause problems there. + + If unsure, say Y here. + endmenu
diff --git a/drivers/base/dd.c b/drivers/base/dd.c
index 7dc04ee81c8b..269ea76c1a4f 100644
--- a/drivers/base/dd.c
+++ b/drivers/base/dd.c@@ -417,6 +417,13 @@ int driver_probe_device(struct device_driver *drv, struct device *dev) if (!device_is_registered(dev)) return -ENODEV; +#if IS_ENABLED(CONFIG_DELAY_DEVICE_PROBES) + if (!driver_deferred_probe_enable && dev->probe_late) { + driver_deferred_probe_add(dev); + return 0; + } +#endif + pr_debug("bus: '%s': %s: matched device %s with driver %s\n", drv->bus->name, __func__, dev_name(dev), drv->name);
diff --git a/include/linux/device.h b/include/linux/device.h
index 8e7b806f0744..e64f4c7e243d 100644
--- a/include/linux/device.h
+++ b/include/linux/device.h@@ -744,6 +744,7 @@ struct device_dma_parameters { * * @offline_disabled: If set, the device is permanently online. * @offline: Set after successful invocation of bus type's .offline(). + * @probe_late: If set, device will be probed in the late initcall level. * * At the lowest level, every device in a Linux system is represented by an * instance of struct device. The device structure contains the information
@@ -828,6 +829,7 @@ struct device { bool offline_disabled:1; bool offline:1; + bool probe_late:1; }; static inline struct device *kobj_to_dev(struct kobject *kobj)
--
2.4.3