| Message ID | 1448976866-7892-2-git-send-email-m.szyprowski@samsung.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
On 1 December 2015 at 14:34, Marek Szyprowski <m.szyprowski@samsung.com> wrote: > From: Tomeu Vizoso <tomeu.vizoso@collabora.com> > > Allow implementations of the match() callback in struct bus_type to > return errors and if it's -EPROBE_DEFER then queue the device for > deferred probing. > > This is useful to buses such as AMBA in which devices are registered > before their matching information can be retrieved from the HW > (typically because a clock driver hasn't probed yet). > > Signed-off-by: Tomeu Vizoso <tomeu.vizoso@collabora.com> > [changed if-else code structure, adjusted documentation to match the code] > Signed-off-by: Marek Szyprowski <m.szyprowski@samsung.com> > --- > Documentation/driver-model/porting.txt | 6 ++++-- > drivers/base/dd.c | 24 ++++++++++++++++++++++-- > include/linux/device.h | 2 +- > 3 files changed, 27 insertions(+), 5 deletions(-) > > diff --git a/Documentation/driver-model/porting.txt b/Documentation/driver-model/porting.txt > index 92d86f7..453053f 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 a641cf3..793e915 100644 > --- a/drivers/base/dd.c > +++ b/drivers/base/dd.c > @@ -490,6 +490,7 @@ 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 > @@ -500,8 +501,17 @@ 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); > > @@ -621,6 +631,7 @@ 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 > @@ -632,8 +643,17 @@ 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 b8f411b..d4e7d1f 100644 > --- a/include/linux/device.h > +++ b/include/linux/device.h > @@ -70,7 +70,7 @@ 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 > + * is added for this bus. It should return a positive value if the Perhaps add some more information about what happens when returning error codes!? > * given device can be handled by the given driver. > * @uevent: Called when a device is added, removed, or a few other things > * that generate uevents to add the environment variables. > -- > 1.9.2 > Besides the minor nit above, you may add my: Reviewed-by: Ulf Hansson <ulf.hansson@linaro.org> Kind regards Uffe -- To unsubscribe from this list: send the line "unsubscribe linux-samsung-soc" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
diff --git a/Documentation/driver-model/porting.txt b/Documentation/driver-model/porting.txt index 92d86f7..453053f 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 a641cf3..793e915 100644 --- a/drivers/base/dd.c +++ b/drivers/base/dd.c @@ -490,6 +490,7 @@ 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 @@ -500,8 +501,17 @@ 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); @@ -621,6 +631,7 @@ 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 @@ -632,8 +643,17 @@ 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 b8f411b..d4e7d1f 100644 --- a/include/linux/device.h +++ b/include/linux/device.h @@ -70,7 +70,7 @@ 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 + * is added for this bus. It should return a positive value if the * given device can be handled by the given driver. * @uevent: Called when a device is added, removed, or a few other things * that generate uevents to add the environment variables.