need to downgrade, downgrade to PIO, as it has been shown if we got CRC errors
in Ultra-DMA mode, we will have silent data corruption in multiword DMA mode
(isn't IDE wonderfull ? :).
Set timeout to 1s for "normal" ata I/O, to minimise the effects of missed
interrupts.
In wdc_probe_caps() add code to guess the ATA revision supported (if
ATA4 if Ultra-DMA, ATA2 if PIO mode > 2). We can't rely on param.atap_ata_major
here, at last one Ultra-DMA drive claims to support only ATA-3.
Use the ATA version in ata_perror(), and to try a flush cache command
in a shutdown hook for IDE drives.
the capacity based on the c/h/s numbers. In fact, don't use the c/h/s
numbers for much of anything.
For ATA-4 drives or later, always use LBA mode, since it's now required.
Collectively, this allows >8GB disks (like the 12GB Bigfoot) to work.
* Fix bug in wdc that would overflow ATAPI transfer length.
* Improve wdc probe code so that 'wdc' is probed in if present
even if there are no drives attached, and so that it works
properly even if the only device is an ATAPI slave.
* bus_space-ify.
* split the ISA attachment from the wdc driver, and remove
ISA dependencies from non-ISA files.
* claim that wd and wdc are now machine-independent (probably not
completely true, but mostly so; they at least work on arm32 and
i386).
* Various other minor fixups and cleanups, some of which were pointed
out by Kazuki Sakamoto.
(currently only CD-ROM drives on i386). The sys/dev/scsipi system provides 2
busses to which devices can attach (scsibus and atapibus). This needed to
change some include files and structure names in the low level scsi drivers.
