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Date: Mon, 28 Jan 2002 18:13:40 +0100
From: Kristian <kristian.peters@korseby.net>
To: Ed Sweetman <ed.sweetman@wmich.edu>
Cc: akpm@zip.com.au, benh@kernel.crashing.org, linux-kernel@vger.kernel.org
Subject: Re: [CFT] Bus mastering support for IDE CDROM audio
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Ed Sweetman <ed.sweetman@wmich.edu> wrote:
> I've always been able to get it back to dma for packet by forcing the
> drive to sleep mode and then letting the kernel wake it.   I guess I'll
> try this 3rd version patch when I get back from class today and see if
> that still works.   
> 
> hdparm -Y /dev/cdrom    
> 
> then go and set dma again with hdparm.   
> 
> Although this could just be fickleness of my cdrom.  

It works for the second one (the HP writer). But the kernel completely hangs for 2 seconds trying to wake up the drive (with 2.4.18-pre3-ac2).

My log shows:
 hdd: DMA disabled
 hdd: drive not ready for command
 hdd: ATAPI reset complete

But preemption does help in that case.

The first cd-rom drive does not support sleep or standby commands. ;-(

*Kristian

  :... [snd.science] ...:
 ::
 :: http://www.korseby.net
 :: http://gsmp.sf.net
  :.........................:: ~/$ kristian@korseby.net :
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