Yup. Rob was looking for regression - I'm not set up to test
SCSI CDROMs here.
The second patch goes back to reading a bunch of frames all
inside the same request, rather than one frame at a time. This
is because the cdparanoia guys tell me that it can prevent
single-request overruns and underruns and other data loss which
occurs around the start and end of the request. So with a walking-window
read algorithm from userspace they can pick up data which would
otherwise be lost.
Also it seems that some devices aren't happy with the larger transfers,
so it looks like the algorithm needs to become:
- Try multiple frames, DMA
- If that fails, try single frames, DMA
- If that fails, fall back to PIO
While all the time not altering the DMA status of the drive for
block-based filesystem I/O.
> not a whole lot of pio aic7xxx adapters out there :-)
>
Thank heavens for that (I _knew_ I shouldn't have stuck my
nose in drivers/ide/).
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