diff options
| -rw-r--r-- | Documentation/driver-model/porting.txt | 6 | ||||
| -rw-r--r-- | drivers/base/dd.c | 24 | ||||
| -rw-r--r-- | include/linux/device.h | 7 |
3 files changed, 31 insertions, 6 deletions
diff --git a/Documentation/driver-model/porting.txt b/Documentation/driver-model/porting.txt index 92d86f7271b4..453053f1661f 100644 --- a/Documentation/driver-model/porting.txt +++ b/Documentation/driver-model/porting.txt @@ -340,8 +340,10 @@ comparison: int (*match)(struct device * dev, struct device_driver * drv); -match should return '1' if the driver supports the device, and '0' -otherwise. +match should return positive value if the driver supports the device, +and zero otherwise. It may also return error code (for example +-EPROBE_DEFER) if determining that given driver supports the device is +not possible. When a device is registered, the bus's list of drivers is iterated over. bus->match() is called for each one until a match is found. diff --git a/drivers/base/dd.c b/drivers/base/dd.c index c4da2df62e02..16688f50729c 100644 --- a/drivers/base/dd.c +++ b/drivers/base/dd.c @@ -560,6 +560,7 @@ static int __device_attach_driver(struct device_driver *drv, void *_data) struct device_attach_data *data = _data; struct device *dev = data->dev; bool async_allowed; + int ret; /* * Check if device has already been claimed. This may @@ -570,8 +571,17 @@ static int __device_attach_driver(struct device_driver *drv, void *_data) if (dev->driver) return -EBUSY; - if (!driver_match_device(drv, dev)) + ret = driver_match_device(drv, dev); + if (ret == 0) { + /* no match */ return 0; + } else if (ret == -EPROBE_DEFER) { + dev_dbg(dev, "Device match requests probe deferral\n"); + driver_deferred_probe_add(dev); + } else if (ret < 0) { + dev_dbg(dev, "Bus failed to match device: %d", ret); + return ret; + } /* ret > 0 means positive match */ async_allowed = driver_allows_async_probing(drv); @@ -691,6 +701,7 @@ void device_initial_probe(struct device *dev) static int __driver_attach(struct device *dev, void *data) { struct device_driver *drv = data; + int ret; /* * Lock device and try to bind to it. We drop the error @@ -702,8 +713,17 @@ static int __driver_attach(struct device *dev, void *data) * is an error. */ - if (!driver_match_device(drv, dev)) + ret = driver_match_device(drv, dev); + if (ret == 0) { + /* no match */ return 0; + } else if (ret == -EPROBE_DEFER) { + dev_dbg(dev, "Device match requests probe deferral\n"); + driver_deferred_probe_add(dev); + } else if (ret < 0) { + dev_dbg(dev, "Bus failed to match device: %d", ret); + return ret; + } /* ret > 0 means positive match */ if (dev->parent) /* Needed for USB */ device_lock(dev->parent); diff --git a/include/linux/device.h b/include/linux/device.h index 6d6f1fec092f..8f2ec813d215 100644 --- a/include/linux/device.h +++ b/include/linux/device.h @@ -70,8 +70,11 @@ extern void bus_remove_file(struct bus_type *, struct bus_attribute *); * @dev_groups: Default attributes of the devices on the bus. * @drv_groups: Default attributes of the device drivers on the bus. * @match: Called, perhaps multiple times, whenever a new device or driver - * is added for this bus. It should return a nonzero value if the - * given device can be handled by the given driver. + * is added for this bus. It should return a positive value if the + * given device can be handled by the given driver and zero + * otherwise. It may also return error code if determining that + * the driver supports the device is not possible. In case of + * -EPROBE_DEFER it will queue the device for deferred probing. * @uevent: Called when a device is added, removed, or a few other things * that generate uevents to add the environment variables. * @probe: Called when a new device or driver add to this bus, and callback |