Some clarification on VICP

Abhishek Singh Sisodia

I am experiencing an interesting problem in VICP. I am calling a VICP lib function which is taking two input buffers(Through DMA) and is producing an output buffer. I am also doing some operation on DSP which is also reading( remember just reading not updating) the same two buffres and updating the third buffer.

The VICP and DSP are on the same set of buffers in parallel. My ques is: " Is this possible?" I mean reading the same set of buffers by DSP and VICP is possible or not. I have doubt since my output is not proper in such a case and when i am executing the two sequentially then everything works fine.

Well can anyone have any idea why this strange behaviour is seen?

Do Reply

Thanks and Regards

Abhishek Singh

over 15 years ago

0 RandyP over 15 years ago

TI__Guru* 84110 points

Which DSP are you using? And it may be helpful to be more specific on the VICP lib funciton you are calling.

If you are using one of the DM or OMAP parts, then Digial Media Processors forum may be a better place to seek help. But we will see.

0 Gagan Maur over 15 years ago in reply to RandyP

TI__Expert 8150 points

Abhishek, if you are using the shared buffers as read only, there shouldn't be any problem. But note, once the DSP reads these buffers, they will be in the DSP cache. If the shared buffers were later updated by the VICP, the DSP won't see them till the time the buffers are in its cache. Similarly, if the DSP updates the shared buffers later and VICP tries to read them, the VICP won't see the updates as the updates done by the DSP may still be in its cache.
Try introducing cache flush on the DSP after the operation on the shared buffer is finished
Gagan