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On Intel Apllo Lake platform, the VBus will drop after the SOC suspended,
hence during the SOS resuming process, there will be a disconnecting event
and a connecting event sent to each native USB device in order.
This patch will use new strategy for S3 resuming emultion.
1. The DM set PORTSC register to 'no device attached' state when S3
suspending started,
2. SOS resuming starts and do nothing for device disconnecting event,
3. 'Cache' device connecting event and don't report it to UOS,
4. UOS believe no device attached due to PORTSC register state and
begin to clear the resource allocated for the device before S3
suspending,
5. DM receives the Disable Slot command from UOS and report the 'cached'
device connecting event to UOS, hence trigger the emulation behavior
for the device.
The purpose of this strategy is to let UOS resuming proceed as quickly as
possible, which means the UI will be turned on quickly to user.
Tracked-On: #1893
Signed-off-by: Xiaoguang Wu <xiaoguang.wu@intel.com>
Reviewed-by: Liang Yang <liang3.yang@intel.com>
Acked-by: Yu Wang <yu1.wang@intel.com>