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Bug 3583

Summary: X11 touch device can be permanently lost [Patch]
Product: SDL Reporter: Volumetric <demlow>
Component: videoAssignee: Sam Lantinga <slouken>
Status: RESOLVED FIXED QA Contact: Sam Lantinga <slouken>
Severity: major    
Priority: P2    
Version: 2.0.5   
Hardware: x86_64   
OS: Linux   
Attachments: Adds a reset of the X11 touch devices when they are lost

Description Volumetric 2017-02-10 21:56:03 UTC 
Created attachment 2697 [details]
Adds a reset of the X11 touch devices when they are lost

In X11 the SDL error "Unknown touch device" can occur after which the application stops recognizing touch events. For a kiosk-type application this results in a hang as far as the user is concerned. This is reproducible on HP Z220/Z230/Z240 workstations by swapping USB cables for a while and it also occurs with no physical changes, probably due to USB device power management. A workaround is to make SDL re-enumerate the touch devices like it does at startup. A patch is attached.
Comment 1 Sam Lantinga 2017-02-11 19:15:37 UTC 
Workaround has been applied:
https://hg.libsdl.org/SDL/rev/5a77f977ad95

I wonder if there is an X11 event that is sent when the touch device goes away and needs to be re-enumerated?