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The returned status code can provide this information. If the device is still idle, the driver can submit another idle request IRP. Note The idle request IRP completion routine should not block waiting for a D0 power request to complete.
The completion routine can be called in the context of a power IRP by the hub driver, and blocking on another power IRP in the completion routine can lead to a deadlock. The following list indicates how a completion routine for an idle request should interpret some common status codes:.
Indicates that the device should no longer be suspended. However, drivers should verify that their devices are powered, and put them in D0 if they are not already in D0. Indicates that the device driver requested a D3 power state for its device. Indicates that the bus driver already holds an idle request IRP pending for the device.
Only one idle IRP can be pending at a time for a given device. Submitting multiple idle request IRPs is an error on the part of the power policy owner, and should be addressed by the driver writer. The following code example shows a sample implementation for the idle request completion routine. The bus driver either an instance of the hub driver or the generic parent driver determines when it is safe to suspend its device's children.
If it is, it calls the idle notification callback routine supplied by each child's client driver. In Windows XP, a driver must rely on an idle notification callback routine to selectively suspend a device. If a driver running in Windows XP puts a device in a lower power state directly without using an idle notification callback routine, this might prevent other devices in the USB device tree from suspending.
This allows the callback routine to block while it waits for the power state change request to complete. The callback routine is invoked only while the system is in S0 and the device is in D0.
The USB 2. Downstream devices that are not already suspended detect the Idle state on their upstream port and enter the suspend state on their own. Windows does not implement Global Suspend in this manner.
The Windows 7 USB hub driver will selectively suspend any hub where all of its attached devices are in D1 , D2 , or D3 device power state. This diagram illustrates a situation very similar to the one depicted in the section 'Conditions for Global Suspend in Windows XP'. However, in this case Device 3 qualifies as an Idle device. To fix your Drivers problems you will need to know the particular model of the USB device you are having problems with.
Once you have the details you can search the manufacturers website for your drivers and, if available, download and install these drivers.
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