| 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. |
| |
| |
