From: Jeff Garzik <jgarzik@pobox.com>
To: Bartlomiej Zolnierkiewicz <bzolnier@gmail.com>
Cc: Linux IDE <linux-ide@vger.kernel.org>
Subject: Re: libata vs ATAPI
Date: Tue, 12 Oct 2004 16:50:20 -0400 [thread overview]
Message-ID: <416C438C.4010902@pobox.com> (raw)
In-Reply-To: <58cb370e04101213215ce9a23c@mail.gmail.com>
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
> Then REPORT_LUNS errors out (dev_stat = 0x51)...
This doesn't surprise me, I bet that many ATAPI devices might not like
REPORT LUNS
> I've noticed that DMA is used by default for all packet commands
> which doesn't seem to be wise thing to do so I disabled it.
DMA is _never_ used for packet commands, only for packet data.
libata enables DMA at the maximum level supported by both the device and
host controller. I definitely want to do this by default.
> 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. :)
> Also ATAPI-SCSI emulation is still missing in libata-scsi.c.
I wish to minimize the emulation. That means no read/write emulation,
just modify INQUIRY to report MMC, and do auto-sense (as it is presented
to the SCSI layer).
> I'm sure you know more about what needs to be done.
> Could you make some nice, detailed TODO? :-)
Pat LaVarre had IOmega ATAPI devices working, once he hand-hacked
REQUEST SENSE. As for to-do list, I think this email covers it. Here's
a summary...
* possibly avoid REPORT LUNS for ATAPI devices
* when check condition occurs, automatically request sense inside
driver, and put that data into the sense buffer
* make INQUIRY report SCSI version MMC-3 (or later...)
* support strange sector sizes
Jeff
next prev parent reply other threads:[~2004-10-12 20:50 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 [this message]
2004-10-12 21:17 ` Bartlomiej Zolnierkiewicz
2004-10-12 21:22 ` Jeff Garzik
2004-10-12 21:36 ` Bartlomiej Zolnierkiewicz
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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