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driver core: prevent deferred probe with platform_driver_probe

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Prevent drivers relying on platform_driver_probe from requesting
deferred probing in order to avoid further futile probe attempts (either
the driver has been unregistered or its probe function has been set to
platform_drv_probe_fail when probing is retried).

Note that several platform drivers currently return subsystem errors
from probe and that these can include -EPROBE_DEFER (e.g. if a gpio
request fails).

Add a warning to platform_drv_probe that can be used to catch drivers
that inadvertently request probe deferral while using
platform_driver_probe.

Signed-off-by: Johan Hovold <jhovold@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Johan Hovold 2013-09-23 16:27:26 +02:00 committed by Greg Kroah-Hartman
parent eee0316497
commit 3f9120b042
2 changed files with 14 additions and 4 deletions
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17
drivers/base/platform.c
View file

@ -488,6 +488,11 @@ static int platform_drv_probe(struct device *_dev)
if (ret && ACPI_HANDLE(_dev))
acpi_dev_pm_detach(_dev, true);
if (drv->prevent_deferred_probe && ret == -EPROBE_DEFER) {
dev_warn(_dev, "probe deferral not supported\n");
ret = -ENXIO;
}
return ret;
}
@ -553,8 +558,7 @@ EXPORT_SYMBOL_GPL(platform_driver_unregister);
/**
* platform_driver_probe - register driver for non-hotpluggable device
* @drv: platform driver structure
* @probe: the driver probe routine, probably from an __init section,
* must not return -EPROBE_DEFER.
* @probe: the driver probe routine, probably from an __init section
*
* Use this instead of platform_driver_register() when you know the device
* is not hotpluggable and has already been registered, and you want to
@ -565,8 +569,7 @@ EXPORT_SYMBOL_GPL(platform_driver_unregister);
* into system-on-chip processors, where the controller devices have been
* configured as part of board setup.
*
* This is incompatible with deferred probing so probe() must not
* return -EPROBE_DEFER.
* Note that this is incompatible with deferred probing.
*
* Returns zero if the driver registered and bound to a device, else returns
* a negative error code and with the driver not registered.
@ -576,6 +579,12 @@ int __init_or_module platform_driver_probe(struct platform_driver *drv,
{
int retval, code;
/*
* Prevent driver from requesting probe deferral to avoid further
* futile probe attempts.
*/
drv->prevent_deferred_probe = true;
/* make sure driver won't have bind/unbind attributes */
drv->driver.suppress_bind_attrs = true;

1
include/linux/platform_device.h
View file

@ -178,6 +178,7 @@ struct platform_driver {
int (*resume)(struct platform_device *);
struct device_driver driver;
const struct platform_device_id *id_table;
bool prevent_deferred_probe;
};
#define to_platform_driver(drv) (container_of((drv), struct platform_driver, \