What: /sys/devices/.../state_synced Date: May 2020 Contact: Saravana Kannan 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. Writing "1" to this file will force a call to the device's sync_state() function if it hasn't been called already. The sync_state() call happens independent of the state of the consumer devices.