Trouble setting up libiio dma buffer and xilinx dma

I'm trying to use libiio in my platform driver to facilitate data egress from the PL to the process subsystem via Xilinx AXI DMA, but I am getting an error with devm_iio_dmaengine_buffer_setup()

I followed some of the examples in the adi-linux project and in my tree. It seems fairly straightforward? My procedure is as follows:

1. get dma name from a device tree property of with my device, in my case it is 'axi_dma_psd'
2. allocate iio device
3. allocate iio channel specification (1 channel)
4. populate iio channel spec
5. setup dmaengine buffer, returns errno -19 (ENODEV)
6. register iio device

Here's my DMA symbol definition in the dts:

axi_dma_psd = "/amba_pl@0/dma@20180000000";

here's the Xilinx DMA node:

               dma@20180000000 {                          
                        xlnx,include-sg;                
                        clock-names = "s_axi_lite_aclk\0m_axi_sg_aclk\0m_axi_s2mm_aclk";
                        interrupts = <0x00 0x5e 0x04>;
                        clocks = <0x10 0x11 0x11>;                      
                        interrupt-parent = <0x05>;
                        xlnx,addrwidth = <0x20>;
                        compatible = "xlnx,axi-dma-7.1\0xlnx,axi-dma-1.00.a";       
                        interrupt-names = "s2mm_introut";
                        xlnx,sg-length-width = <0x16>;    
                        reg = <0x201 0x80000000 0x00 0x10000>;
                        phandle = <0x58>;           
                        #dma-cells = <0x01>;
                                                              
                        dma-channel@20180000030 {
                                xlnx,device-id = <0x00>;
                                interrupts = <0x00 0x5e 0x04>;
                                compatible = "xlnx,axi-dma-s2mm-channel";
                                dma-channels = <0x01>;
                                xlnx,datawidth = <0x20>;
                        };                        
                };   

If I disable the buffer setup I can register the iio device and the channel appears in sysfs with the name I gave it: psd_magsq0:

root@xilinx-vck190-20221:/sys/bus/iio/devices# ls -latr
total 0
lrwxrwxrwx 1 root root 0 Sep 23 20:37 iio:device1 -> ../../../devices/platform/amba_pl@0/20200000000.psd_wrapper/iio:device1
drwxr-xr-x 4 root root 0 Jan 19 2038 ..
lrwxrwxrwx 1 root root 0 Jan 19 2038 iio:device0 -> ../../../devices/platform/axi/f1270000.sysmon/iio:device0
drwxr-xr-x 2 root root 0 Jan 19 2038 .

fwiw looks like this kernel (xilinx fork) has libiio 0.21:

root@xilinx-vck190-20221:~# ls /usr/lib/libiio.so.0* -la
lrwxrwxrwx 1 root root 14 Mar 9 2018 /usr/lib/libiio.so.0 -> libiio.so.0.21
-rwxr-xr-x 1 root root 137112 Mar 9 2018 /usr/lib/libiio.so.0.21

I suspect IIO or the dmaengine can't find the dma device or I need to modify my dts somehow. I'm not sure how to troubleshoot from here. Any advice is much appreciated.