[wdmaudiodev] Re: GetMapping fails immediately in MappingAvailable
- From: Eugene Muzychenko <emuzychenko@xxxxxxxxx>
- To: Jeff Pages <wdmaudiodev@xxxxxxxxxxxxx>
- Date: Mon, 27 Oct 2008 09:53:16 +0600
Hello Jeff,
> it suggests there might be something suspicious going on in the
> MappingAvailable - GetMapping logic.
It looks like PortCls holds KS_READ/KS_WRITE IRP for some reason. When
IRP arrives, PortCls calls MappingAvailable but doesn't return a
mapping from GetMapping. Some time later or when another IRP arrives,
PortCls calls MappingAvailable again and returns a mapping from
GetMapping.
> I've only ever observed my problem on Vista - all my WavePCI drivers
> on XP have been quite well behaved as far as I'm aware.
I suspect this problem is due to DMA_ADAPTER/DmaOperations emulation
because my driver is virtual and controls no read hardware. For
virtual drivers, DMA logic is emulated by HAL. I implemented my own
emulation for 64-bit systems but it follows the same logic.
Regards,
Eugene
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