Openmoko Bug #2328: touschreen sometimes stops generating events

[Openmoko Public Trac]

#2328: touschreen sometimes stops generating events
-----------------------------+----------------------------------------------
 Reporter:  lindi            |          Owner:  openmoko-kernel
     Type:  defect           |         Status:  new            
 Priority:  normal           |      Milestone:                 
Component:  System Software  |        Version:                 
 Severity:  normal           |       Keywords:  touchscreen    
 Haspatch:  0                |      Blockedby:                 
Estimated:                   |    Patchreview:                 
 Blocking:                   |   Reproducible:  rarely         
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 Steps to reproduce:
 1) hexdump -C /dev/input/event1
 2) touch the touchscreen

 Expected results:
 2) some events are generated

 Actual results:
 2) nothing is generated

 More info:
 1) This started to happen when I upgraded from andy-tracking
 a3587e4ed77974ad to andy-tracking a15608f241a40b41 and disabled
 CONFIG_DEBUG_KERNEL and CONFIG_PREEMPT.
 2) sudo lsof | grep event1 shows that only Xorg keeps the device open =>
 there is nothing running EVIOGRAB that could disable events.
 3) open files of Xorg:
 {{{
 lindi at ginger:~$ sudo ls -l /proc/$(pidof X)/fd
 total 0
 l-wx------ 1 root root 64 Jan 15 10:38 0 -> /var/log/Xorg.0.log
 lrwx------ 1 root root 64 Jan 15 10:38 1 -> socket:[1745]
 lrwx------ 1 root root 64 Jan 15 10:38 10 -> socket:[1781]
 lrwx------ 1 root root 64 Jan 15 10:38 11 -> socket:[1965]
 lrwx------ 1 root root 64 Jan 15 10:38 12 -> socket:[3064]
 lrwx------ 1 root root 64 Jan 15 10:38 13 -> socket:[49650]
 lrwx------ 1 root root 64 Jan 15 10:38 14 -> socket:[3082]
 lrwx------ 1 root root 64 Jan 15 10:38 15 -> socket:[51145]
 lrwx------ 1 root root 64 Jan 15 10:38 17 -> socket:[62017]
 lrwx------ 1 root root 64 Jan 15 10:38 18 -> socket:[43528]
 lrwx------ 1 root root 64 Jan 15 10:38 19 -> socket:[64051]
 l-wx------ 1 root root 64 Jan 15 10:38 2 -> /var/log/xdm.log
 lrwx------ 1 root root 64 Jan 15 10:38 20 -> socket:[64120]
 lrwx------ 1 root root 64 Jan 15 10:38 23 -> socket:[64206]
 lrwx------ 1 root root 64 Jan 15 10:38 3 -> socket:[1746]
 lr-x------ 1 root root 64 Jan 15 10:38 4 -> /usr/lib/xorg/protocol.txt
 lrwx------ 1 root root 64 Jan 15 10:38 5 -> /dev/tty2
 lrwx------ 1 root root 64 Jan 15 10:38 6 -> /dev/apm_bios
 lrwx------ 1 root root 64 Jan 15 10:38 7 -> /dev/fb0
 lr-x------ 1 root root 64 Jan 15 10:38 8 -> /dev/input/event1
 lrwx------ 1 root root 64 Jan 15 10:38 9 -> socket:[1778]
 }}}
 3) strace shows that Xorg does

 {{{
 select(256, [1 3 5 6 8 9 10 11 12 13 14 15 16 17 18 19 20 23], NULL, NULL,
 NULL) = 1 (in [11])
 }}}

 every second but it never returns that there is something to read from fd
 8 (the event1 device).
 4) This happened immediately after resume so suspend/resume code might
 have something to do with this.
 5) Stopping Xorg did not fix this
 6) Starting Xorg did not fix this
 7) Suspending/resuming again did not fix this
 8) the interrupt count of s3c2410_action in /proc/interrupts does increase
 every time I touch the screen so the hardware is not totally dead

 9) Just in case this happens next, what extra information should I gather
 to make this easier to fix?

-- 
Ticket URL: <https://docs.openmoko.org/trac/ticket/2328>
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