Linux/TMS320DM8148: DMA by external event: how to fix crossbar in Linux 2.6.37?

Part Number:TMS320DM8148

Tool/software: Linux

Hello.

I have to do DMA transfers triggered by EDMA_EVT1 pin. 
I see the DMA1 channel reserved in the linux kernel devices.c file, so in my understanding, I need to use the crossbar.

But the crossbar configuration is also defined in this devices.c file as static and the API functions do not provide a way to change it.

So, the question is:
If I ask edma_alloc_channel () function for a channel, I may be given an arbitrary DMA channel - how can I set the crossbar with the correct value for the received channel?

Thanks a lot ahead.