Alpha blending mixer's alpha blending port.

Hi,

I would suggest checking that you implemented the Avalon-ST specs (and Avalon-ST Video specs) correctly for all four inputs (din_* and alpha_*). There are independent ready signals for the sources and for the alpha sources and there is no guarantee that the inputs will be ready simultaneously. You should also avoid making any assumptions on their behaviour. For instance it could be possible, in theory, that the alpha channel is not ready until you have fed a dozen of pixels into the corresponding din input, It is easy to create a deadlock if trying to feed all inputs from a single source module.

One of the ready signal probably goes low at column 6 because there is a small FIFO at each input of the core and it can contain about that many samples. This is expected and the core will go ready again once it is actually processing the data it buffered.

One of the four ready signals going down at column 300 seems a bit unusual if you have valid data available on all four mixer inputs. It may be due to another core downstream applying back-pressure but this could also be the time when a spec violation has already happened.

vgs