1What: /sys/devices/.../state_synced 2Date: May 2020 3Contact: Saravana Kannan <saravanak@google.com> 4Description: 5 The /sys/devices/.../state_synced attribute is only present for 6 devices whose bus types or driver provides the .sync_state() 7 callback. The number read from it (0 or 1) reflects the value 8 of the device's 'state_synced' field. A value of 0 means the 9 .sync_state() callback hasn't been called yet. A value of 1 10 means the .sync_state() callback has been called. 11 12 Generally, if a device has sync_state() support and has some of 13 the resources it provides enabled at the time the kernel starts 14 (Eg: enabled by hardware reset or bootloader or anything that 15 run before the kernel starts), then it'll keep those resources 16 enabled and in a state that's compatible with the state they 17 were in at the start of the kernel. The device will stop doing 18 this only when the sync_state() callback has been called -- 19 which happens only when all its consumer devices are registered 20 and have probed successfully. Resources that were left disabled 21 at the time the kernel starts are not affected or limited in 22 any way by sync_state() callbacks. 23 24 Writing "1" to this file will force a call to the device's 25 sync_state() function if it hasn't been called already. The 26 sync_state() call happens independent of the state of the 27 consumer devices. 28 29 30