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