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Re: Timecritical interrupt-debuging ... printf in DSR's ...Cyg_Scheduler_Implementation::rem_thread() ... cyg_assert_fail()


Oliver Munz wrote:

Hi

To debug an USB-driver, I used diag_printf(). Unfortunatly this function blocks my DSR longer then the USB-specifications allowed to. So I tryed to send the debug-output over the standard at91-serial-driver, configurated with a 2kByte buffer.

This works fine a short time and fail:

CYG_ASSERT( ((queue_map & (1<<pri))!=0) == ((!run_queue[pri].empty())!=0), "Map and queue disagree");
in:


7 cyg_assert_fail() at e:\ecos\packages\infra\current\src\buffer.cxx:737
6 Cyg_Scheduler_Implementation::rem_thread() at e:\ecos\packages\kernel\current\src\sched\mlqueue.cxx:323
5 Cyg_Condition_Variable::wait_inner() at e:\ecos\packages\kernel\current\src\sync\mutex.cxx:636
4 serial_write() at e:\ecos\packages\io\serial\current\src\common\serial.c:362
3 cyg_io_write() at e:\ecos\packages\io\common\current\src\iosys.c:178



I don't know if it's allowed to use the buffered IO from ISR and DSR's. If everybody know's if it should work or not in threory, let me know.... Im also intressted in other hints how to debug driveres...


Thanks
Oliver Munz

Another thing you can consider is make a first pass at the driver using a high-priority thread to service the device, instead of the DSR. Just have the DSR signal the thread using a semaphore or similar. Than you can then send a fair amount of debug output to a hardware-driven serial port (from the thread context) and still remain within the timing constraints of USB. You may just need to try responding to the USB host before doing your printf()'s in certain time-constrained situations, such as when you get a SET_ADDRESS.

This will obviously effect your throughput (not to mention all the serial output slowing things down) but you'll be able to get through a USB enumeration no problem. Once it's all working you can bring the code back into the DSR and remove the printing. Or even better, leave a configuration option to switch between the "debug" and "release" options.

Frank Pagliughi


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