Does the driver support single channel DMA?

[jimenaCabrejas]

Hello!

I'm working on a design where I will be receiving data in the PL and I'm using a DMA to pass it to the PS. The DMA only has the write channel activated. This is my Vivado design:

I'm using Petalinux 2020.2 and my pl.dtsi looks like this

/ {
	amba_pl: amba_pl {
		#address-cells = <1>;
		#size-cells = <1>;
		compatible = "simple-bus";
		ranges ;
		axi_dma_0: dma@40400000 {
			#dma-cells = <1>;
			clock-names = "s_axi_lite_aclk", "m_axi_sg_aclk", "m_axi_s2mm_aclk";
			clocks = <&clkc 15>, <&clkc 15>, <&clkc 15>;
			compatible = "xlnx,axi-dma-7.1", "xlnx,axi-dma-1.00.a";
			interrupt-names = "s2mm_introut";
			interrupt-parent = <&intc>;
			interrupts = <0 29 4>;
			reg = <0x40400000 0x10000>;
			xlnx,addrwidth = <0x20>;
			xlnx,include-sg ;
			xlnx,sg-length-width = <0xe>;
			dma-channel@40400030 {
				compatible = "xlnx,axi-dma-s2mm-channel";
				dma-channels = <0x1>;
				interrupts = <0 29 4>;
				xlnx,datawidth = <0x20>;
				xlnx,device-id = <0x0>;
			};
		};
	};
};

In my system-user.dtsi I have

&amba_pl{
    axidma_chrdev: axidma_chrdev@0 {
            compatible = "xlnx,axidma-chrdev";
            dmas = <&axi_dma_0 0>;
            dma-names = "rx_channel";
    };
};

When I try to load the driver in petalinux using insmod I get the following error

xilinx_axidma: loading out-of-tree module taints kernel.
axidma: axidma_dma.c: axidma_request_channels: 651: Unable to get slave channel 0: rx_channel.
axidma: probe of amba_pl:axidma_chrdev@0 failed with error -38

I'm I missing something in my projecto? Does the driver support one channel DMAs? Do I need to change something to make it work?

Thank you and best regards

[dahunt]

Hi,

Did you ever get a solution to your problem above? I am running into the same issue under 2022.1.
Thanks!

[Timgrau]

Hey @dahunt @jimenaCabrejas, due to this issue #24 (comment) have you tried to change the device id for the dma channel in the axidma_chrdev node, in system-user.dtsi to 1? i.e. dmas = <&axi_dma_0 1>;

[dahunt]

Hey @Timgrau,

Yup! that was exactly the problem. I also had to provide an device id. I'm still a newbie at this... but here is my working user dt entry for the Rx only streaming DMA project for your reference.

/include/ "system-conf.dtsi"
/ {
};

&amba_pl {
dma_proxy {
compatible = "xlnx,dma_proxy";
dmas = <&hier_DataGen_axi_dma_0 1>;
dma-names = "dma_proxy_rx";
dma-coherent;
};

    hier_DataGen_axi_dma_0: dma@80020000 {
            dma-channel@80020030 {
                    xlnx,device-id = <0x1>;
            };
    };

};

[Timgrau]

Thank you @dahunt for the reference. Did you use the dma-proxy driver: https://github.com/Xilinx-Wiki-Projects/software-prototypes/tree/master/linux-user-space-dma?

You did not attached this devie-tree-nodes into your system-user.dtsi right? Where did you add them? Did you enabled the fpga-manager in your petalinux config file?

In your PetaLinux project:
cat project-spec/configs/config | grep FPGA

[dantepayne]

Hey @Timgrau,

Yup! that was exactly the problem. I also had to provide an device id. I'm still a newbie at this... but here is my working user dt entry for the Rx only streaming DMA project for your reference.

/include/ "system-conf.dtsi" / { };

&amba_pl { dma_proxy { compatible = "xlnx,dma_proxy"; dmas = <&hier_DataGen_axi_dma_0 1>; dma-names = "dma_proxy_rx"; dma-coherent; };

    hier_DataGen_axi_dma_0: dma@80020000 {
            dma-channel@80020030 {
                    xlnx,device-id = <0x1>;
            };
    };

};

Hey @dahunt ，I meet the same problem，Have you solve it ？

[dantepayne]

When I change DT Like this：
&amba_pl {
axidma_chrdev: axidma_chrdev@0 {
compatible = "xlnx,axidma-chrdev";
dmas = <&axi_dma_0 1>;
dma-names = "rx_channel";
};
};

&axi_dma_0 {
dma-channel@a0000030 {
xlnx,device-id = <0x1>;
};
};

The Driver collapse.Segment fault occur.
But I use this DT：
&amba_pl {
axidma_chrdev: axidma_chrdev@0 {
compatible = "xlnx,axidma-chrdev";
dmas = <&axi_dma_0 0>;
dma-names = "rx_channel";
};
};

&axi_dma_0 {
dma-channel@a0000030 {
xlnx,device-id = <0x1>;
};
};
The Problem is the same.
xilinx_axidma: loading out-of-tree module taints kernel.
axidma: axidma_dma.c: axidma_request_channels: 651: Unable to get slave channel 0: rx_channel.
axidma: probe of amba_pl:axidma_chrdev@0 failed with error -38
Here is my pl.dtsi:
amba_pl: amba_pl@0 {
#address-cells = <2>;
#size-cells = <2>;
compatible = "simple-bus";
ranges ;
axi_dma_0: dma@a0000000 {
#dma-cells = <1>;
clock-names = "s_axi_lite_aclk", "m_axi_s2mm_aclk";
clocks = <&zynqmp_clk 71>, <&zynqmp_clk 71>;
compatible = "xlnx,axi-dma-7.1", "xlnx,axi-dma-1.00.a";
interrupt-names = "s2mm_introut";
interrupt-parent = <&gic>;
interrupts = <0 89 4>;
reg = <0x0 0xa0000000 0x0 0x10000>;
xlnx,addrwidth = <0x20>;
xlnx,sg-length-width = <0x17>;
dma-channel@a0000030 {
compatible = "xlnx,axi-dma-s2mm-channel";
dma-channels = <0x1>;
interrupts = <0 89 4>;
xlnx,datawidth = <0x20>;
xlnx,device-id = <0x0>;
};
};
axi_gpio_dma_rstn: gpio@a0010000 {
#gpio-cells = <3>;
clock-names = "s_axi_aclk";
clocks = <&zynqmp_clk 71>;
compatible = "xlnx,axi-gpio-2.0", "xlnx,xps-gpio-1.00.a";
gpio-controller ;
reg = <0x0 0xa0010000 0x0 0x80>;
xlnx,all-inputs = <0x0>;
xlnx,all-inputs-2 = <0x0>;
xlnx,all-outputs = <0x1>;
xlnx,all-outputs-2 = <0x0>;
xlnx,dout-default = <0x00000000>;
xlnx,dout-default-2 = <0x00000000>;
xlnx,gpio-width = <0x1>;
xlnx,gpio2-width = <0x20>;
xlnx,interrupt-present = <0x0>;
xlnx,is-dual = <0x0>;
xlnx,tri-default = <0xFFFFFFFF>;
xlnx,tri-default-2 = <0xFFFFFFFF>;
};
axi_gpio_dma_start: gpio@a0020000 {
#gpio-cells = <3>;
clock-names = "s_axi_aclk";
clocks = <&zynqmp_clk 71>;
compatible = "xlnx,axi-gpio-2.0", "xlnx,xps-gpio-1.00.a";
gpio-controller ;
reg = <0x0 0xa0020000 0x0 0x80>;
xlnx,all-inputs = <0x0>;
xlnx,all-inputs-2 = <0x0>;
xlnx,all-outputs = <0x1>;
xlnx,all-outputs-2 = <0x0>;
xlnx,dout-default = <0x00000000>;
xlnx,dout-default-2 = <0x00000000>;
xlnx,gpio-width = <0x1>;
xlnx,gpio2-width = <0x20>;
xlnx,interrupt-present = <0x0>;
xlnx,is-dual = <0x0>;
xlnx,tri-default = <0xFFFFFFFF>;
xlnx,tri-default-2 = <0xFFFFFFFF>;
};
};

[HongHanPT]

Hey @dantepayne ，I meet the same problem，Have you solve it？

[dantepayne]

Hey @dantepayne ，I meet the same problem，Have you solve it？
I have solve it,it is wired because the number in "dmas" is not the number of devicetree node for axi_dma_0, you can find in xilinx_dma.c -> mm2s:0 s2mm:1,if you use rx channel,it should be 1 like this :

&amba_pl {
axidma_chrdev: axidma_chrdev@0 {
compatible = "xlnx,axidma-chrdev";
dmas = <&axi_dma_0 1>;
dma-names = "rx_channel";
};
}
&axi_dma_0 {
dma-channel@a0000030 {
xlnx,device-id = <0x0>;
};
};