Windows System Software -- Consulting, Training, Development -- Unique Expertise, Guaranteed Results


More Info on Driver Writing and Debugging

The free OSR Learning Library has more than 50 articles on a wide variety of topics about writing and debugging device drivers and Minifilters. From introductory level to advanced. All the articles have been recently reviewed and updated, and are written using the clear and definitive style you've come to expect from OSR over the years.

Check out The OSR Learning Library at:

Before Posting...

Please check out the Community Guidelines in the Announcements and Administration Category.


frog981frog981 Member Posts: 2

I understand from the documentation that this call can't be made if the driver is not a power policy owner. What (technique) is the equivalent of this call for a rawpdo to prevent
the parent device from entering idle while its processing an ioctl? The parent device is also not a power policy owner


  • Doron_HolanDoron_Holan Member - All Emails Posts: 10,584

    You left out a little bit of relevant information related to roles and state. What type of driver are you writing? From your description, it is a filter driver that enumerates a raw PDO. Is that correct? What is the device class that the filter is installed in? Usually the pattern enumerating a raw PDO from a filter is due to the inability to open the filter directly, where the keyboard and mouse class are the usual classes where a filter does this.

  • frog981frog981 Member Posts: 2

    Hi Doron, yes, fd and its a usb device.

  • Doron_HolanDoron_Holan Member - All Emails Posts: 10,584

    "it is a usb device" is not an answer to the "what device class is the filter driver installed in?" What device class is your filter installed in? To help you out, what does the Class= line look like in the [Version] section of your filter's INF?

  • Muthu_KumarMuthu_Kumar Member Posts: 31

    It is a custom sensor device and we don't own the function driver but have access to device spec etc.

  • Doron_HolanDoron_Holan Member - All Emails Posts: 10,584

    Is it a custom function driver or inbox? Regardless, you need to poke the function driver to power up the device/keep it from idling. Typically this means sending io to the function driver to perform the operation you want to execute. The function driver will then power up (if idle) to process the IO request.

  • Muthu_KumarMuthu_Kumar Member Posts: 31

    Makes sense. Will give it a try. Thx

Sign In or Register to comment.

Howdy, Stranger!

It looks like you're new here. If you want to get involved, click one of these buttons!

Upcoming OSR Seminars
OSR has suspended in-person seminars due to the Covid-19 outbreak. But, don't miss your training! Attend via the internet instead!
Developing Minifilters 24 May 2021 Live, Online
Writing WDF Drivers 14 June 2021 Live, Online
Internals & Software Drivers 2 August 2021 Live, Online
Kernel Debugging 27 Sept 2021 Live, Online