correct use of bus_dmamap_sync

Singh, Vijay Vijay.Singh at netapp.com
Tue Oct 25 10:02:54 PDT 2005


man  bus_dma(9)

> -----Original Message-----
> From: Dinesh Nair [mailto:dinesh at alphaque.com] 
> Sent: Tuesday, October 25, 2005 7:03 AM
> To: Dinesh Nair
> Cc: freebsd-hackers at freebsd.org
> Subject: Re: correct use of bus_dmamap_sync
> 
> 
> 
> On 10/25/05 21:15 Dinesh Nair said the following:
> > the pseudo code for the read and write, called during an interrupt 
> > cycle, are:
> > 
> > rx_func()
> > {
> >     POSITION A
> > 
> >     while(there_is_some_data) {
> >         memcpy(somebuf, readbuf)
> >     }
> >     POSITION B
> > }
> > 
> > tx_func()
> > {
> >     POSITION C
> > 
> >     while(there_is_some_data) {
> >         memcpy(writebuf, somebuf)
> >     }
> >     POSITION D
> > }
> > 
> > the question is, what op should i use for bus_dmamap_sync 
> in positions 
> > A, B, C and D ?
> 
> responding to my own request, i mean which of 
> BUS_DMASYNC_PREREAD, BUS_DMASYNC_POSTREAD, 
> BUS_DMASYNC_PREWRITE, BUS_DMASYNC_POSTWRITE should i use, and where ?
> 
> -- 
> Regards,                           /\_/\   "All dogs go to heaven."
> dinesh at alphaque.com                (0 0)    http://www.alphaque.com/
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