Re: CVS commit: src/sys/dev/ieee1394

[KIYOHARA Takashi <kiyohara%kk.iij4u.or.jp@localhost>]

Hi! Tsutsui-san,


From: Izumi Tsutsui <tsutsui%ceres.dti.ne.jp@localhost>
Date: Mon, 1 May 2006 21:16:33 +0900

> > The ieee1394 driver's DMA descriptor cannot be operated if it is not a
> > memory of coherent now.  This is because processing that rewrites
> > descriptor without stopping DMA under operation is done. 
> > 
> > In that case, ieee1394 today will not be able to be used.  Is there
> > something any idea?
> 
> I don't think it's an ieee1394 specific problem because
> many other drivers (SCSI, Ethernet) notify DMA xfer completion
> via DMA descriptors. How does BUS_DMA_COHERENT
> (i.e. uncached DMA descriptor) help in your ieee1394 case?

known me too.  i.e. fxp(4), tlp(4)...
Neither fxp(4) nor tlp(4) seem to do sync to the DMA descriptor. 


> i.e. is there any benefits by removing sync ops?

I am expecting that be able to work early by this change.
--
kiyohara