hdparm -Y /dev/cdrom
then go and set dma again with hdparm.
Although this could just be fickleness of my cdrom.
On Mon, 2002-01-28 at 04:51, Andrew Morton wrote:
> firstname.lastname@example.org wrote:
> > >At no stage does a packet-mode DMA error turn off drive-level
> > >DMA. This is because some devices seem to perform ordinary
> > >ATA DMA OK, but screw up packet DMA.
> > >
> > >The kernel internally retries the requests when it performs fallback,
> > >so userspace shouldn't see any disruption as the kernel works
> > >out what to do.
> > >
> > >Once the drive has fallen back to single-frame (or PIO mode) for
> > >packet reads, the only way to get it back to a higher level is
> > >a reboot.
> > Doesn that mean that a bad media (typically a scratched CDROM) will
> > cause the drive to revert to PIO until next reboot ?
> Nope. This error handling is specifically for busmastering
> errors, not for media errors.
> I've tested media errors (whiteboard marker scribblings on the
> CD do this nicely). DMA errors (bad return value from
> HWIF->dmaproc) I can only simulate.
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