Subject: Re: bus_dmamap_sync not enough ?
To: Jason R Thorpe <thorpej@wasabisystems.com>
From: Matthew Jacob <mjacob@feral.com>
List: tech-kern
Date: 02/11/2003 11:49:58
I hope the OpenBSD folks are monitoring this exchange. The exact same
topic (even wrt the same h/w) came up on one of their mailing lists
recently.
On Tue, 11 Feb 2003, Jason R Thorpe wrote:
> On Tue, Feb 11, 2003 at 12:35:01PM -0500, Stephan Uphoff wrote:
>
> > The i82257 driver ignores this problem and just illegally calls
> > bus_dmamap_sync with
> > BUS_DMASYNC_POSTXXXX flags with full knowledge that the DMA might not have
> > completed.
> > ( When it finds out that the DMA did not complete it just calls bus_dmamap_sync
> > again with BUS_DMASYNC_PREXXXX op flags)
>
> This is not illegal... this is an acceptable/intended use of the interface
> (I should know -- I designed the interface and wrote the code that you're
> citing :-)
>
> --
> -- Jason R. Thorpe <thorpej@wasabisystems.com>
>