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

[Frank Pagliughi <fpagliughi@mindspring.com>]

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


-- 
Before posting, please read the FAQ: http://ecos.sourceware.org/fom/ecos
and search the list archive: http://ecos.sourceware.org/ml/ecos-discuss