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From: dturvene <dturvene@dahetral.com>
To: linux-input@vger.kernel.org
Subject: ACPI and the psmouse alps driver
Date: Fri, 25 Jan 2013 11:07:49 -0500	[thread overview]
Message-ID: <5102ADD5.1020900@dahetral.com> (raw)

While I'm thinking of it, in the my last alps driver dkms, I put in an 
ACPI interface to uniquely detect the touchpad type.  After spending a 
good couple of days figuring out the ACPI spec and this mysterious _HID 
(hardware id) and _CID (compatibility id) as it relates to how ALPS 
identifies its touchpads, I can confirm Linus' quote "ACPI is a complete 
design disaster in every way. But we're kind of stuck with it."   Some 
ALPS touchpads have different _HID values.  Some have the same _HID but 
different behavior.

As far as I can tell ACPI has varying degrees of usefulness based on the 
h/w manufacturer.  The ALPS MS Windows drivers appear to use ACPI to 
figure out if the touchpad is, in fact, from ALPS and then a complicated 
series of proprietary retrievals to figure out the behavior.



                 reply	other threads:[~2013-01-25 16:07 UTC|newest]

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