On Mon, 28 Jul 2003, Andries Brouwer wrote:
> > Well, are timeouts needed at all?
>
> Yes. We send a command to the keyboard. It may react, or it may not.
But we need not wait for that actively. If we are unsure about a result
of a command, then we may send a command in question followed with an echo
request. This assures an IRQ will finally arrive and if no command
response arrives before an echo response, then the keyboard ignored the
command. I used this approach many years ago to differ between PS/2
keyboards (which respond with 0xfa,0xab,0x83 to a request for ID) and
genuine PC/AT ones (which respond with lone 0xfa). It worked.
-- + Maciej W. Rozycki, Technical University of Gdansk, Poland + +--------------------------------------------------------------+ + e-mail: macro@ds2.pg.gda.pl, PGP key available +- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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