Windows 10 DFx (Directed Power Management Framework) questions for USB Devices

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wm6057

l Q1. The USB fingerprint device, which supports Selective suspend (the device enters suspend after 5 seconds), but we found that the driver of the DFx feature has more power consumption than the unsupported DFx driver .


The situation is as follows: (The Blue words are what we doubt about)


Before Driver

Support DFx Driver

Is there a registered finger

OS send capture data IOCTL

Status

Status

Enrolling fingerprint

Yes

Yes

Power consumption drops after 5 seconds.

Continuous power consumption

No

Yes

Power consumption drops after 5 seconds.

Continuous power consumption

Lock screen

Yes

Yes

Power consumption drops after 5 seconds.

Continuous power consumption

No

No

Power consumption drops after 5 seconds.

Power consumption drops after 5 seconds.

S3

(modern standby)

Yes

Yes

Power consumption drops after 5 seconds.

*Manual enter S3: Power consumption drops after 60 seconds.

*use command enter S3: Power consumption drops after 5 seconds.

No

No

Power consumption drops after 5 seconds.

Power consumption drops after 5 seconds.

l Q2. Why are the power saving behaviors different between *manual enter S3(Start menu -> power -> sleep) and*command (.\pwrtest.exe /directedfx /device”xxxx”)?

l Q3. According to the above, in the specification of power consumption measurement, Which one should be the main one? (Manual enter S3 or use command enter S3)

l Q4. Does Microsoft have a DFx power consumption spec?

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