Re: [CFT] Bus mastering support for IDE CDROM audio

From: Kristian (
Date: Mon Jan 28 2002 - 12:13:40 EST

Ed Sweetman <> 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. ;-(


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