Hello, I wrote:
supported. I couldn't track down where that bit was actually
defined in the first place, all the way back to ATA-1 it seems to
be indicated as reserved. Actually, I'm not sure why the drive
cares in the first place, it would seem like a pure host
controller issue..
It goes back before IDE into the depths of the original compaq
spec. When
you have a device wired basically directly to the ISA bus
(original IDE)
ISA has only 8/16-bit data bus, so it could not have mattered
there...
Depends what a 32bit I/O looks like on the 16bit bus - timing wise.
Two 16-bit reads at addresses 0x1x0 and 0x1x2 with the programmed
recovery time, IIRC... It's just occured to me that in case of the
16-bit bus it should be how the drive treated the accesses at address
0x1x2 with IOCS16 asserted that could have mattered. If it honored
them, 32-bit I/O could have worked even on a dumb ISA "controller",
if not -- no way (unless you really had *something* between the ISA
and the IDE cable).
Oh, -IOCS16 is driven by device, not host. I give up then. :-)
OTOH, it definitely could work if the drive asserted it for the I/O
port 0x1x2 at least for the data transfer phase (and probably even if it
always asserted -IOCS16 for this address).
That pre-historic word indeed could have made sense then...
MBR, Sergei
--
To unsubscribe from this list: send the line "unsubscribe linux-ide" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
