From: Bartlomiej Zolnierkiewicz <bzolnier@gmail.com>
To: Jeff Garzik <jgarzik@pobox.com>
Cc: Linux IDE <linux-ide@vger.kernel.org>, Jens Axboe <axboe@suse.de>
Subject: Re: libata vs ATAPI
Date: Tue, 12 Oct 2004 23:36:22 +0200 [thread overview]
Message-ID: <58cb370e0410121436749e2bfb@mail.gmail.com> (raw)
In-Reply-To: <20041012212225.GA2625@havoc.gtf.org>
On Tue, 12 Oct 2004 17:22:25 -0400, Jeff Garzik <jgarzik@pobox.com> wrote:
> On Tue, Oct 12, 2004 at 11:17:38PM +0200, Bartlomiej Zolnierkiewicz wrote:
> > On Tue, 12 Oct 2004 16:50:20 -0400, Jeff Garzik <jgarzik@pobox.com> wrote:
> > > Bartlomiej Zolnierkiewicz wrote:
> > > > Hi Jeff,
> > > >
> > > > Is libata currently supposed to work with ATAPI
> > > > (I know about lack of REQUEST_SENSE support)?
> > > >
> > > > With ATA_ENABLE_ATAPI defined INQUIRY seems to succeed for my
> > > > TOSHIBA ODD-DVD SD-R6372 but empty info is printed by SCSI layer.
> > >
> > > I get this too
> >
> > OTOH ide-scsi gets correct INQUIRY output
>
> I spoke incorrect, I meant to say the exact opposite...!
>
> I get correct INQUIRY output.
damn ;-)
> > > libata enables DMA at the maximum level supported by both the device and
> > > host controller. I definitely want to do this by default.
> >
> > Me too but I suppose that there are many devices which don't like it
> > (otherwise restrictions in ide-cd and ide-scsi make no sense).
> >
> > Jens?
>
> The IDE layer currently figures that all my test CD-ROMs support DMA, so
> I would like libata to do that too ;-)
INQUIRY is done in PIO in ide-scsi and it works for this device
> > > > Unfortunately it doesn't help because atapi_pio_sector() assumes
> > > > transfer length to be % SECTOR_SIZE and transfer length for INQUIRY
> > > > is mere 36 bytes so this fails.
> > >
> > > Yes, you are welcome to fix this assumption. :)
> >
> > Another bug in this area: bcount is set to 64 * 1024 (0xFFFF) but
> > ATA/ATAPI spec defines max bcount as 0xFFFE and there must
> > be some reason why ide-scsi limits it to 63 * 1024 and ide-cd to
> > 32 * 1024.
>
> bcount should be set to 8K (one SATA FIS) for PIO,
> and 0xFFFF for DMA. It's not used for DMA.
According to ATA/ATAPI-5 spec bcount is ignored for
non-PIO transfers.
It sets bcount also for no-data which seems wrong.
> Where is this code in libata?
atapi_xlat() in libata-scsi.c
Bartlomiej
next prev parent reply other threads:[~2004-10-12 21:36 UTC|newest]
Thread overview: 16+ messages / expand[flat|nested] mbox.gz Atom feed top
2004-10-12 20:21 libata vs ATAPI Bartlomiej Zolnierkiewicz
2004-10-12 20:50 ` Jeff Garzik
2004-10-12 21:17 ` Bartlomiej Zolnierkiewicz
2004-10-12 21:22 ` Jeff Garzik
2004-10-12 21:36 ` Bartlomiej Zolnierkiewicz [this message]
2004-10-12 21:45 ` Jeff Garzik
2004-10-12 23:03 ` Bartlomiej Zolnierkiewicz
2004-10-15 13:13 ` Jens Axboe
2004-10-15 17:17 ` Jeff Garzik
2004-10-12 21:30 ` Jeff Garzik
2004-10-12 21:39 ` Bartlomiej Zolnierkiewicz
2004-10-12 21:46 ` Jeff Garzik
2004-10-14 7:13 ` Jens Axboe
2004-10-14 19:19 ` Bartlomiej Zolnierkiewicz
2004-10-14 21:15 ` Bartlomiej Zolnierkiewicz
2004-10-15 5:00 ` Jeff Garzik
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