Re: [Xen-devel] [PATCH 2 of 5] rombios/ata: Do not wait for BSY to be set

[Alan Cox <alan@xxxxxxxxxxxxxxxxxxx>]

> Does this actually do anything useful?  I'd guess that on qemu the extra
> outb has no effect and on real hardware that needed a delay here, one
> I/O cycle would not be enough.

It ought to be plenty - the time before the response is valid from an ATA
command is very short but in the real hardware world most definitely
present and important.

However you also need to think about the state of the device registers
after the second outb. If you don't wait for BSY and for some reason it's
delayed in the emulation or on a multiprocessor what occurs.

Might be safer to do

        outb(0x80,0x00)
        await_ide(...)

at which point the await_ide would run once in the usual case.

Alan

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