HDL OPenCL issue (Avalon ST Interface Issues)

Hi,

Please can someone did work with HDL and OpenCL (Avalon ST interface).

I did a very simple project with HDL-kernel Co-design like the first advanced example in altera design examples. And my question is about valid and ready signal in Avalon interface ? I force valid signal to 0. When valid signal is 0 it suppose no valid data is being to be transfered.

What I did, I tried to print with printf fonction the data transfered from HDL module to kernel when valid is 0 and the problem I have exactly the same data transfered.

My data is always transfered from HDL to Kernel and it doesn't matter when valid signal is 0 (invalid data) or 1 (valid data) !!!

I don't know how to fix it ? What happens with Avalon interface when valid Signal is 0 ?

Thank you.