As I said before, our pipeline is transparent and opaque to the cpu. To implement vblank, all I have is the xilinx vdma frame counter interrupt. I was wondering why it was not used in xilinx_drm_crtc_enable_vblank and rather a specific method for vtc and dp was used.

Wouldn't it be possible to call xilinx_drm_crtc_vblank_handler from the DMA completion callback (callback member of dma_async_tx_descriptor)?

It would then work regardless of the pipeline (vtc, dp, or custom) wouldn't it?