gio_write in swi

Ru48071

Hi, All,

We are using c6747 DSP for our development. I have a question about gio_write in a SWI.

According to the BIOS manual, gio_write cannot be called from a SWI. I accidentally used it and it worked with a timing issue. gio_write is one of the last few instructions executed in the SWI. When I stepped through the code from the emulator, the data was transferred out correctly. However, if I let the code free run, the data was not sent out correctly. Then I added some delays after the gio_write and before the exit from SWI, everything worked.

Has anyone used gio_write in a SWI? What is your experience? Why do I need the delay?

Thanks,

over 16 years ago

0 Karl Wechsler over 16 years ago

TI__Mastermind 20805 points

You cannot call GIO_write() from a SWI since GIO_write internally calls SEM_pend() to wait for the I/O to complete. Calling SEM_pend() from SWI or HWI level is not allowed.

0 Peter Myerscough-Jackopson over 16 years ago in reply to Karl Wechsler

Intellectual 500 points

SEM_pend is allowed with a timeout of zero.....

Peter (feeling pedantic....)

0 Karl Wechsler over 16 years ago in reply to Peter Myerscough-Jackopson

TI__Mastermind 20805 points

That's true, but GIO with '0' timeout has problems.

If you don't want to wait on the I/O, you might be able to use 'GIO_submit' API. The man page for that API shows a brief example.

Also, we provide source to GIO module in the product for reference which might help. Look in the <installdir>\packages\ti\bios\src\gio directory.

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gio_write in swi