layer1: crash after receiving TX data

Andreas.Eversberg Andreas.Eversberg at
Mon Aug 16 11:08:27 UTC 2010

me and maybe some of you experiences sudden freeze of the layer1 firmware. it happens sometimes when sending L1CTL_DATA_REQ from layer2 to layer1. i found a way to reproduce it. see for testing it. just apply this patch and uncomment the "´#define" line.
this patch will transmit idle frames, if there is no frame in the tx-queue of lapdm. (DCCH) even if there is a frame to be sent, the lapdm process will wait until the data is confirmed by layer1 until sendig the next frame. this confirm is sent when the data has been transmitted by layer1 (i think). this is why the queue inside layer1 cannot overflow.
this patch does not work correctly somehow. when sending the idle frame, the location update seems not to work. the lapdm fails. but this doesn't matter for the crash-test. until then, more than 20 frames are transmitted. if the mobile application is restarted, more frames will be transmitted. between 45 and 60 frames later the layer1 freezes. the display gets a little darker also.
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