Linux hang

["Siegmund, Jan" <jan.siegmund0@hm.edu>]

Hi all,
does anybody have an idea for the following problem.

* FPGA is programmed using an overlay
* FPGA writes to SDRAM via the FPGA2SDRAM-bridge
* Linux hangs and the watchdog resets the board (the FPGA stays programmed)
* After the reset and boot the FPGA is reprogrammed using the same overlay
* Now, the FPGA can write to the SDRAM without a problem

The environment:

*Board:   DE0-NANO-SoC
*U-Boot: 2017.11
*Kernel:  4.14.0-rc7 (review-v4.14-rc7-non-dt-support-v5.1 branch)

The overlay:

/dts-v1/;
/plugin/;

/ {
	fragment@0 {
		target-path = "/soc/base_fpga_region";
		#address-cells = <1>;
		#size-cells = <1>;
		__overlay__ {
			#address-cells = <1>;
			#size-cells = <1>;
			fpga-bridges = <&fpga_bridge0 &fpga_bridge1>;
			firmware-name = "foo_base.rbf";

			fpga-bridge@ffc25080 {
				compatible = "altr,socfpga-fpga2sdram-bridge";
				reg = <0xffc25080 0x4>;
				bridge-enable = <1>;
			};

			foo@ff200000 {
				compatible= "altr,bar";
				interrupt-parent = <&intc>;
				interrupts = <0 40 4>;
			};

		};
	};
};

Thanks