diff options
| -rw-r--r-- | Documentation/ABI/testing/sysfs-devices-state_synced | 24 | ||||
| -rw-r--r-- | drivers/base/dd.c | 22 |
2 files changed, 46 insertions, 0 deletions
diff --git a/Documentation/ABI/testing/sysfs-devices-state_synced b/Documentation/ABI/testing/sysfs-devices-state_synced new file mode 100644 index 000000000000..0c922d7d02fc --- /dev/null +++ b/Documentation/ABI/testing/sysfs-devices-state_synced @@ -0,0 +1,24 @@ +What: /sys/devices/.../state_synced +Date: May 2020 +Contact: Saravana Kannan <saravanak@google.com> +Description: + The /sys/devices/.../state_synced attribute is only present for + devices whose bus types or driver provides the .sync_state() + callback. The number read from it (0 or 1) reflects the value + of the device's 'state_synced' field. A value of 0 means the + .sync_state() callback hasn't been called yet. A value of 1 + means the .sync_state() callback has been called. + + Generally, if a device has sync_state() support and has some of + the resources it provides enabled at the time the kernel starts + (Eg: enabled by hardware reset or bootloader or anything that + run before the kernel starts), then it'll keep those resources + enabled and in a state that's compatible with the state they + were in at the start of the kernel. The device will stop doing + this only when the sync_state() callback has been called -- + which happens only when all its consumer devices are registered + and have probed successfully. Resources that were left disabled + at the time the kernel starts are not affected or limited in + any way by sync_state() callbacks. + + diff --git a/drivers/base/dd.c b/drivers/base/dd.c index 2aef1e4ce60a..a0b9ff5220cf 100644 --- a/drivers/base/dd.c +++ b/drivers/base/dd.c @@ -462,6 +462,18 @@ static void driver_deferred_probe_add_trigger(struct device *dev, driver_deferred_probe_trigger(); } +static ssize_t state_synced_show(struct device *dev, + struct device_attribute *attr, char *buf) +{ + bool val; + + device_lock(dev); + val = dev->state_synced; + device_unlock(dev); + return sprintf(buf, "%u\n", val); +} +static DEVICE_ATTR_RO(state_synced); + static int really_probe(struct device *dev, struct device_driver *drv) { int ret = -EPROBE_DEFER; @@ -535,9 +547,16 @@ re_probe: goto dev_groups_failed; } + if (dev_has_sync_state(dev) && + device_create_file(dev, &dev_attr_state_synced)) { + dev_err(dev, "state_synced sysfs add failed\n"); + goto dev_sysfs_state_synced_failed; + } + if (test_remove) { test_remove = false; + device_remove_file(dev, &dev_attr_state_synced); device_remove_groups(dev, drv->dev_groups); if (dev->bus->remove) @@ -567,6 +586,8 @@ re_probe: drv->bus->name, __func__, dev_name(dev), drv->name); goto done; +dev_sysfs_state_synced_failed: + device_remove_groups(dev, drv->dev_groups); dev_groups_failed: if (dev->bus->remove) dev->bus->remove(dev); @@ -1104,6 +1125,7 @@ static void __device_release_driver(struct device *dev, struct device *parent) pm_runtime_put_sync(dev); + device_remove_file(dev, &dev_attr_state_synced); device_remove_groups(dev, drv->dev_groups); if (dev->bus && dev->bus->remove) |