Re: [PATCH 24/44] Workaround i8042 chips with broken MUX mode

From: Andries Brouwer
Date: Sat Mar 27 2004 - 19:31:50 EST

On Tue, Mar 16, 2004 at 10:24:09AM -0800, Dmitry Torokhov wrote:
> Vojtech Pavlik wrote:

> > + /* Workaround for broken chips which seem to
> support MUX, but in reality don't. */

Why call them "broken"? Better to delete that word.

> > + /* They all report version 12.10 */
> > + if (mux_version == 0xCA)
> > + return -1;
> I think it should be 0xAC (0xA4 with 4th bit flipped)
> as the version reported is 10.12.

Yes. I have seen one such report. Have there been more?

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.

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