Child Device Driver

Hi,

I've understood that I need to write a child display driver to be able
to access the I2C bus using VIDEO_PORT_I2C_INTERFACE. But I have no
idea how to create Child Driver for Mini Port Driver and the inf file.

It would be great if someone help me in this regard.

Thanks
VK

AlexN
Tue Mar 14 08:46:27 CST 2006

In order to create the inf file u can use the geninf tool supplied with the
ddk.
For the child driver I think you should obtain a videoport's device object
pointer
calling IoGetDeviceObjectPointer passing a symbolic link like
\??\PCI#VEN_XXXX&DEV_XXXXXXXXXXX for your display adapter...(you can get it
calling IoGetDeviceInterfaces for the display adapter guid)
When you attach your own device object to device stack you can pass the
videoport's device object pointer instead of what you get from i/o manager
and your driver will be a child of the display adapter!

I'm sorry to tell you that as soon as you will achieve your goal you will
realize the interface is useless for a child driver of the display adapter
cause you can't successfully call i2c read and write functions unless you
pass them a callback structure filled with 4 function pointers to read/write
i2c data and clock lines implemented by the miniport driver....

if you find a way to get these 4 pointers please let me know...

good luck,

Alex

"VK" wrote:

> Hi,
>
> I've understood that I need to write a child display driver to be able
> to access the I2C bus using VIDEO_PORT_I2C_INTERFACE. But I have no
> idea how to create Child Driver for Mini Port Driver and the inf file.
>
> It would be great if someone help me in this regard.
>
> Thanks
> VK
>
>