From mboxrd@z Thu Jan 1 00:00:00 1970 From: Henrik Rydberg Subject: Re: [PATCH 0/4] Alternative approach to MT_TOOL_ENVELOPE Date: Thu, 16 Dec 2010 15:41:33 +0100 Message-ID: <4D0A251D.8060803@bitmath.org> References: <4D0897F3.7040500@bitmath.org> <4D08FD74.4060403@canonical.com> <4D0918A8.6080207@bitmath.org> <4D092F61.7000405@canonical.com> Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit Return-path: Received: from csmtp1.one.com ([195.47.247.21]:49271 "EHLO csmtp1.one.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755765Ab0LPOle (ORCPT ); Thu, 16 Dec 2010 09:41:34 -0500 In-Reply-To: <4D092F61.7000405@canonical.com> Sender: linux-input-owner@vger.kernel.org List-Id: linux-input@vger.kernel.org To: Chase Douglas Cc: Dmitry Torokhov , Chris Bagwell , Peter Hutterer , linux-input , "linux-kernel@vger.kernel.org" >>> >>> With regards to partial MT devices, if the device provides a single >>> valued property, such as pressure and tool type for synaptics, it may >>> only be provided through the traditional property semantics, i.e. >>> ABS_PRESSURE and BTN_TOOL_*. If the device provides multiple values for >>> a property, then ABS_MT_* types may be used as well to provide up to two >>> values, though the client should understand there's no direct >>> correlation between the slot's coordinates and the property. I could see >>> this being used to provide info on multiple tool types or a high and low >>> pressure. >>> >>> Enforcing the above behaviour provides even more information about the >>> capabilities of the device based solely on the evdev codes published. >> >> >> Looks good, but I do not think we need to formalize all possibilities here, only >> the usage of MT data for bounding rectangle and ST data for finger count. >> Referring to the patch just sent: whenever INPUT_PROP_SEMI_MT is true, this >> behavior is expected. In the event of new odd hardware, the combination of a new >> property quirk and a documented recipe should do the trick. > > Would you feel comfortable stating the above in less concrete terms, as > sort of a best practices guide? I'd like to know for this specific case > if you agree beyond ST finger count data, or if you feel we should do > something else like always provide as much data as possible in MT > properties? It's a real corner case, and I don't care too much one way > or another. I just don't want synaptics implemented one way, elantech > another, etc. A driver can still choose to report ABS_MT_PRESSURE for instance, in which case it is assumed to make sense for individual fingers/corners. For semi-mt devices, it seems reasonable to go to the ST variants to collect information not provided via the MT protocol. I see no immediate reason to specify beyond that point. Thanks, Henrik