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

Jens Axboe
2002-01-27T21:26:21Z

On Sun, Jan 27 2002, Robert Love wrote:
> On Fri, 2002-01-25 at 03:40, Andrew Morton wrote:
> > Reading audio from IDE CDROMs always uses PIO. This patch
> > teaches the kernel to use DMA for the CDROMREADAUDIO ioctl.
> > [...]
> > This code has not been tested for its effects upon SCSI-based
> > CDROM readers. It needs to be.
>
> Andrew,
>
> I wanted to confirm success of testing the patch with a SCSI CD-ROM
> (Plextor UltraPlex Wide on aic7xxx). I used your updated patch off your
> website.
>
> Audio rip completed without error. Performance seems the same, which I
> assume is to be expected with SCSI readers.

sr already uses DMA for all transfers, so no performance gain was to be
expected there. problem is ide-cd using pio for all packet command data
transfers currently (modulo fs read write requests, of course)

not a whole lot of pio aic7xxx adapters out there :-)

--
Jens Axboe