Hello, again. Forgot one thing. Alan Cox wrote: >> all we can use is how the BIOS configured it. I suppose BIOS does it by >> issuing trial commands which I don't think adding to libata is a good idea. > > The BIOS does it by asking the hardware somehow. I traced one or two > BIOSes that far. The info is there but its not documented in the > slightest so only ACPI makes it visible via the BIOS. > >> Can you please lemme know what you don't like about the current >> implementation or what other approach you have in mind? I don't like >> Nvidia PATA either but there are a lot of people using it out there. > > We seem to be able to trust the drives and BIOS ACPI data for Nvidia (at > least what I have seen), so I guess we should simply declare the cable > type unknown, 80 wire if ACPI says it is and then do the drive detect > side ? The drive side can't be trusted. For the drive side detection work properly, there should be a capacitor attached to PDIAG-:CBLID- line so that the drive can tell 40C cable which connects CBLID- to the host connector by sampling while the capacitor is still discharging. If there's no capacitor on the line, 40C and 80C cables behave identically. Voltage rises as soon as CBLID- is disasserted and drive always reports 80C and that's what happens on my A8N-E. Hell of a way to save cost for one capacitor, I guess. :-( -- tejun - 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
