http://mail-index.netbsd.org/tech-kern/2003/09/25/0006.html
This adds a device (atabus) between IDE controllers and wd or atapibus, to
have each ATA channel show up in the device tree. Later there will be atabus
devices in /dev, so that we can do IOCTL on them.
Each atabus has its own kernel thread, to handle operations that needs polling,
e.g. reset and others.
Device probing on each bus it defered to the atabus thread creation.
This allows to do the reset and basic device probes in parallel, which reduce
boot time on systems with several pciide controllers.
most polling.
2) Clean up some goofiness in pciide -- get rid of the whole "candisable" path
(it's gratuitous) and simplify the code by calling pciide_map_compat_intr(),
*_set_modes() and wdc_print_modes() from central locations.
3) Add a register writability and register ghost test to eliminate phantom
drives more quickly.
another function, always doing a page 0 MODE SENSE to get the block
descriptor if we use READ CAPACITY, and use SMS_DBD on the page 4/5 MODE
SENSE. This does one extra command in some cases, but it separates and
simplifies the code a little.
Why do we prefer READ CAPACITY over READ FORMAT CAPACITIES? Two reasons:
1) It's much older and is much less likely to have had its command code
abused, and is thus "safer" to try first. 2) ALL of my USB flash readers
and pen drives screw up their capacity descriptors -- mostly off-by-one
errors in the size (they return the maximum LBA number instead, a la READ
CAPACITY, which has *never* been how READ FORMAT CAPACITIES was documented
in the MMC spec), and one returns the "no media" code on slots that have
media inserted (despite returning almost-correct data otherwise)!
F*** me with a chainsaw.
ready. This avoids gratuitously starting the motor on floppy and CD-ROM
drives, and eliminates the need for the audio playing test in cdopen().
Therefore, also remove PQUIRK_NOSTARTUNIT.
allocation length a little more precisely -- add the space for the header in
cd_mode_sense(). Also delete the XS_CTL_SILENT, since we really do want to
see errors.
Lastly, add a similar wrapper for mode select, simplifying the callers
slightly.
if our other MODE SENSEs fail. Use this code for the optical device case,
at least for now. (We could query the optical media type and do a table
lookup for the geometry, but why bother? Actually, why bother with geometry
at all, but I digress...)
the "bus type" for this.
Merge all the code in the SCSI and ATAPI backends for "cd" devices. All of
the mode page handling and whatnot is general to SCSI MMC devices, and should
never have been separated to begin with. This fixes a variety of problems,
and adds load/unload support for SCSI-attached devices.
wiz