I’ve found that any time I’ve had the hdparm: ioctl 0x304 failed: Inappropriate ioctl for device issue, it’s not necessarily a driver issue, though it could very well be one. However, check your PXE file.

Make sure that the web part of the pxe server: does not look like this:

Make sure you add the trailing slash otherwise you’ll see this issue.

On the same note, make sure your FOG Settings Page :
FOG Configuration (? Circle Icon) -> FOG Settings -> Web Server section -> Web Root also has the trailing slash as this is used to create the boot file for the hosts when tasks are setup.

Hopefully this helps.