Hi all,
Currently I am trying to develop a DRM driver that will use Xilinx VDMA to transfer video data to a HDMI TX Phy and I am facing a difficulty regarding the understanding of the DRM DMA Engine. I looked at several sources and at the DRM core source but the flow of creating and interfacing with the DMA controller is still not clear to me.
At DRI web page the X server is mentioned. Does it mean that the channel creation and handling is done by the X server? If so, what is the DRM driver responsible to do then and what exactly does the DRM core do? As I am using Xilinx VDMA do you foresee any special implementation details?
Just for reference here is the description of the Xilinx VDMA: "The Advanced eXtensible Interface Video Direct Memory Access (AXI VDMA) core is a soft Xilinx Intellectual Property (IP) core providing high-bandwidth direct memory access between memory and AXI4-Stream video type target peripherals including peripherals which support AXI4-Stream Video Protocol." The driver is available at "drivers/dma/xilinx/xilinx_vdma.c".
Another important point: I am using PCI Express connected to a FPGA which has all the necessary components (Xilinx VDMA, I2S, ...) and the HDMI TX Phy.
Looking forward to you help.
Best regards, Jose Miguel Abreu