few question about vpfe driver on dm368

Hi,all 

     1  what's the diffrence of vpfe_isr and vpfe_imp_dma_isr?

     2 vpfe_imp_dma_isr call vpfe_shedule_next_buffer, and it will call update_output_address,who will put the data to this address and how(i mean which function will put data into this address)?

regards

yangchar