Debugging touch input problem
neal at nic-stix.com
Thu Sep 26 17:29:22 UTC 2013
On 09/26/2013 09:32 AM, Daniel d'Andrada wrote:
> On 26/09/13 02:52, Neal Peacock wrote:
>> I'm running down a touch screen input problem and I'm trying to
>> figure out the right place to look. I am porting ubuntu touch and
>> the using mir. My last issue is the touch screen input. I was
>> getting some very erratic results and I'm trying to figure out where
>> it breaks. The screen will react a little to touches but not
>> accurately and most of the gestures do not work, the few that will
>> are sporadic. I have dumped out the touch results from the kernel
>> and all the x,y and id values looks correct as far as I can tell.
>> This driver works under LXDE and Android. lsof seems to show unity
>> is the only process watching these events and it looks like the mir
>> library might be what actually handles input.
>> Is the mir server what handles touch input?
> Yes, it has android-input inside it.
>> I've been checking through the source and I see a references to the
>> Android touch input code. I tried to enable the input report log but
>> I don't seem to see any output with the upstart logs or in logcat.
>> Where does that report go?
>> Does the Android container need to have some touch input service
>> running for it to work? I can't see a service an obvious name.
>> Any help or thoughts appreciated, thank you.
> So, if I understood you correctly you're trying it out on a new
> device? If that's the case it might be that you didn't provide a .idc
> file for your touchscreen (I guess idc stands for "input device
> configuration"). Take a look at InputDevice.cpp and its log messages.
This was exactly the problem. Thank you, I had spent a day and a half
at this and you gave me a 2 minute fix. I wasn't anywhere near figuring
I started by making a port for an eval board with a serial debug port,
the same processor but no touch screen. Once I had resolved all the
boot up issues I moved this to a new port for the actual tablet. The
touch screen config never got brought back from the original android
build but as soon as you mentioned it, there it was.
Touch is working perfectly now.
> Running mir_demo_standalone_inputfilter as root is the best way to
> diagnose input issues. If you're using the latest mir (from bzr repo),
> to get log messages from android-input you will also have to set a
> ANDROID_LOG_TAGS environment variable appropriately. Set it to "*:v"
> to get the most verbose log.
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