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From: "Maciej W. Rozycki" <macro@ds2.pg.gda.pl>
To: Andries Brouwer <aebr@win.tue.nl>
Cc: Alan Cox <alan@lxorguk.ukuu.org.uk>,
	Pete Zaitcev <zaitcev@redhat.com>,
	Chris Heath <chris@heathens.co.nz>,
	Linux Kernel Mailing List <linux-kernel@vger.kernel.org>
Subject: Re: i8042 problem
Date: Mon, 28 Jul 2003 17:43:51 +0200 (MET DST)	[thread overview]
Message-ID: <Pine.GSO.3.96.1030728173054.15233C-100000@delta.ds2.pg.gda.pl> (raw)
In-Reply-To: <20030728145452.GA1753@win.tue.nl>

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        +


  reply	other threads:[~2003-07-28 15:31 UTC|newest]

Thread overview: 19+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2003-07-26  6:11 i8042 problem Pete Zaitcev
2003-07-26  9:36 ` Andries Brouwer
2003-07-27  1:41   ` Chris Heath
2003-07-27  6:06     ` Pete Zaitcev
2003-07-27 10:47       ` Andries Brouwer
2003-07-28  1:55         ` Pete Zaitcev
2003-07-28 11:25           ` Alan Cox
2003-07-28 11:59             ` Andries Brouwer
2003-07-28 14:01               ` Maciej W. Rozycki
2003-07-28 14:54                 ` Andries Brouwer
2003-07-28 15:43                   ` Maciej W. Rozycki [this message]
2003-07-28 15:51                     ` Andries Brouwer
2003-07-29 18:29                       ` Maciej W. Rozycki
2003-08-12 20:46                         ` Vojtech Pavlik
2003-08-13 13:44                           ` Maciej W. Rozycki
2003-07-28 16:07             ` Pete Zaitcev
2003-08-12 20:47               ` Vojtech Pavlik
2003-08-12 20:42         ` Vojtech Pavlik
2003-08-12 23:06           ` Andries Brouwer

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