0001 What: /sys/devices/.../state_synced
0002 Date: May 2020
0003 Contact: Saravana Kannan <saravanak@google.com>
0004 Description:
0005 The /sys/devices/.../state_synced attribute is only present for
0006 devices whose bus types or driver provides the .sync_state()
0007 callback. The number read from it (0 or 1) reflects the value
0008 of the device's 'state_synced' field. A value of 0 means the
0009 .sync_state() callback hasn't been called yet. A value of 1
0010 means the .sync_state() callback has been called.
0011
0012 Generally, if a device has sync_state() support and has some of
0013 the resources it provides enabled at the time the kernel starts
0014 (Eg: enabled by hardware reset or bootloader or anything that
0015 run before the kernel starts), then it'll keep those resources
0016 enabled and in a state that's compatible with the state they
0017 were in at the start of the kernel. The device will stop doing
0018 this only when the sync_state() callback has been called --
0019 which happens only when all its consumer devices are registered
0020 and have probed successfully. Resources that were left disabled
0021 at the time the kernel starts are not affected or limited in
0022 any way by sync_state() callbacks.
0023
0024
