Category Archives: AXI

Linux Kernel 4.4 DTS node for Xilinx AXI-DMA IP.

I recently switch to Linux Kernel 4.4 (from 4.0) for some of my projects and to my no surprise found Xilinx AXI-DMA not working again. This time it complained that it can't find DMA channel: "unable to read dma-channels property" and as result "Probing channels failed." So, looks like Xilinx added support for "multi-channel mode" for kernel driver and this is a big deal! And I waited for this forever!

But, as a result of this - DTS node were changed again, braking compatibility. Also, if you using the only one DMA-channel either MM2S or S2MM channel index in your custom DTS node must be 0 in either case, unlike before if you were using only s2mm index was 1 and if only mm2s index was 0.

So, below example of DTS node for AXI DMA and modified xilinx_dmatest(single channel) which works for me for Linux 4.4

axidma0: axidma@40400000 {
        compatible = "xlnx,axi-dma-1.00.a";
        #dma-cells = <1>;
        reg = <0x40400000 0x10000>;
        interrupt-parent = <&intc>;
        dma-channel@40400030 {
                compatible = "xlnx,axi-dma-s2mm-channel";
                dma-channels = <1>;
                interrupts = <0 29 4>;
                xlnx,datawidth = <32>;
                xlnx,include-dre = <0>;
} ;

dmatest0: dmatest@0 {
	compatible ="xlnx,axi-dma-test-1.00.a";
	dmas = <&axidma0 0>;
	dma-names = "axidma1";

Very useful Zynq and AXI bus tutorials.


Spent couple of my evenings watching this tutorials and found them painfully slow, but very very useful. Unfortunately for me, I'm already passed that point on my "learning curve" of Zynq and AXI4 bus, but still learned quite a few new tricks and got some ideas, especially on creation of AXI peripheral using HLS and RTL design flows. Hope, Mohammadsadegh Sadri will soon move from trivial examples to advanced topics as he promised in his videos.

Anyway, I suggest this tutorials for everyone. Very nice work Mohammadsadegh Sadri !

You can find full list of tutorials here: