From: Dmitry Torokhov <dtor_core@ameritech.net>
To: Andries Brouwer <aebr@win.tue.nl>
Cc: Vojtech Pavlik <vojtech@suze.cz>,
torvalds@osdl.org, vojtech@ucw.cz, linux-kernel@vger.kernel.org
Subject: Re: [PATCH 24/44] Workaround i8042 chips with broken MUX mode
Date: Sat, 27 Mar 2004 22:11:09 -0500 [thread overview]
Message-ID: <200403272211.09229.dtor_core@ameritech.net> (raw)
In-Reply-To: <20040328012507.GA11840@wsdw14.win.tue.nl>
On Saturday 27 March 2004 08:25 pm, Andries Brouwer wrote:
> On Sat, Mar 27, 2004 at 07:40:39PM -0500, Dmitry Torokhov wrote:
>
> > > The Synaptics multiplexing proposal uses 0xf0, 0x56, 0xa4
> > > to activate and 0xf0, 0x56, 0xa5 to deactivate.
> > > In both cases the replies must be 0xf0, 0x56, version.
> > >
> > > Thus, I suppose one might get a more robust detection
> > > by checking that both the activation and deactivation
> > > sequences yield the same version.
> > >
> >
> > Unfortunately in this particular case it looks like something flips
> > 4th bit on some (but not all, like every 3rd) bytes, so it may very
> > well respond with 0xAC to both queries.
>
> If one flips that bit on 0xa5 the result is 0xad, not 0xac.
Yes, you are right.
>
> That the bit is set is not strange.
> The standard PS/2 protocol requires bit 3 in the first word of
> every 3-byte packet to be 1.
If it did it in every 3rd byte and not in response to loopback requiest
but to real data stream coming from a device I would agree...
--
Dmitry
next prev parent reply other threads:[~2004-03-28 3:11 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2004-03-16 18:24 [PATCH 24/44] Workaround i8042 chips with broken MUX mode Dmitry Torokhov
2004-03-18 20:37 ` Vojtech Pavlik
[not found] ` <200403190005.36956.dtor_core@ameritech.net>
2004-03-19 13:58 ` Vojtech Pavlik
2004-03-19 14:21 ` Stefan Smietanowski
2004-03-19 14:30 ` Vojtech Pavlik
2004-03-19 13:56 ` Vojtech Pavlik
2004-03-28 0:29 ` Andries Brouwer
2004-03-28 0:40 ` Dmitry Torokhov
2004-03-28 1:25 ` Andries Brouwer
2004-03-28 3:11 ` Dmitry Torokhov [this message]
2004-03-28 7:45 ` Stefan Smietanowski
-- strict thread matches above, loose matches on Subject: below --
2004-03-16 14:19 [PATCH 23/44] Use __obsolete_setup() in input drivers to warn about obsolete kernel params Vojtech Pavlik
2004-03-16 14:19 ` [PATCH 24/44] Workaround i8042 chips with broken MUX mode Vojtech Pavlik
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