[PATCH evdev 2/3] Add the new valuators for multitouch (rev3)

Stéphane Chatty chatty at enac.fr
Wed Jun 2 10:42:27 PDT 2010

Le 2 juin 10 à 17:51, Benjamin Tissoires a écrit :
>> There seems to be a misunderstanding here. The range of  
>> should ideally be very large, much larger than the number of  
>> supported fingers.
>> What you would want here is the maximum number of slots, according  
>> to the type B
>> protocol. Until then, one should probably support as many fingers  
>> as the
>> valuators can handle.
> Well, I know that ABS_MT_TRACKING_ID shouldn't have anything to do  
> with the number of touchpoints the device can support. However,  
> currently, and for all devices that won't support protocol B (if  
> there are any), this is the only one parameter I know to retrieve  
> this max count. For instance, I thought some drivers of dual  
> touchscreen sends Tracking_id between 1 and 2 (hid-egalax I think).  
> But at least, if the max tracking id is 16, there is no point of  
> creating 24 touches for example.
> I had in mind these dual touch devices in order not polluting their  
> valuators.
> If you have any other suggestion (appart from slots, as this patch  
> does not handle them at all, and a later one will come when it will  
> be upstream), feel free to tell.
> A solution would be to remove this test as dual touch devices could  
> easily use slots I think.

Most devices have low max values of ContactID, similar to the max  
number of touches. But this is not a requirement, and Stantum panels  
have IDs between 0 and 255 (used to be 0-65535 in old firmware  
versions)... If, as is currently done, we direclty map ContactID onto  
ABS_MT_TRACKING_ID, this could a problem couldn't it?


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