W5500 - Reading RTR Register Value FFFF while loading w5500 SPI ethernet driver

Question

Hi Team, We try to interface W5500 SPI Ethernet module to 32-bit SPI interface with our RISC-V development board, We’ve enabled driver support for W5500, But during the kernel boot time, while driver initialisation “w5100_hw_reset” function calling “w5100_read16” function in that function seeing 65535 (FFFF) when tried to print it. But its expecting 2000. Checked MISO and CLK signal in oscilloscope but the MISO value we are seeing other then FFFF but the same value is not reflecting in the driver, please find the logs below for reference. [ 0.000000] Linux version 5.10.41-soc (riscv@riscv) (riscv64-unknown-linux-gnu-gcc (crosstool-NG 1.24.0) 8.3.0, GNU ld (crosstool-NG 1.24.0) 2.32) #4 SMP Wed May 24 14:48:10 IST 2023 [ 3.429923] riscv : priv value 36075584 [ 3.440282] riscv : w5100_read16 65535 My SPI controller only supports 32 Bit slave devices, and do not support 8 & 16 Bit slaves. Please do help me on this. Screenshot from 2023-05-24 18-01-211106×606 75.2 KB Screenshot from 2023-05-24 18-02-17983×533 61 KB Regards, Kavya.

Eugeny · Answer

Kavya1: calling “w5100_read16” function in that function seeing 65535 (FFFF) What register it reads? Did W5500 finish initialization at this time? Kavya1: But its expecting 2000 Why? Kavya1: Checked MISO and CLK signal in oscilloscope but the MISO value we are seeing other then FFFF but the same value is not reflecting in the driver Do you check value at that exactly moment when kernel reads wrong value? What is on the MISO/MOSI wires?

Kavya1 · Answer

Reading rtr register, Its not initialising. In driver code defined rtr register value 2000(0x07D0). In driver code defined spi_read16 function, when we print that function we are observing 65535 (FFFF) value, when we probe MISO and MOSI we’ve observing other then FFFF in oscilloscope, above attached images for CLK and MISO signal. Regards, Kavya.

Kavya1 · Answer

Hi, Currently we are not using any library, enabled driver support for wiznet in 5.10.41 kernel, configured wiznet in device tree node. while booting wiznet driver is not loading it stopping in w5100_read16 () function. is it mandatory to add ioLibrary? Regards, Kavya.

rena · Answer

Hi, What did you write for the device tree code? I was using the dts overlay file provided by version 5.10.x in the Raspberry Pi environment. The code can be found in the link below. Raspberry Pi linux dts overlay - w5500-overlay.dts

Kavya1 · Answer

Hi, Below dts node used : eth1@0 { compatible = “wiznet,w5500”; reg = <0>; interrupt-parent = <&porta>; pinctrl-names = “default”; interrupts = <21 IRQ_TYPE_EDGE_FALLING>; irq-gpios = <&porta 21 GPIO_ACTIVE_HIGH>; mac-address = [00 08 DC 01 02 03]; spi-max-frequency = <35000000>; status = “okay”; } Tested w5100 using spidev_test getting rtr value 07D0, when we try to load Wiznet driver getting 65535(ffff), please find the attached logs below. spidev_test logs: spidev_test -D /dev/spidev0.0 -v -p “\x00\x19\x00\x00\x00” [ 906.293490] cnds_runtime_resume @ 1143 spi mode: 0x0 bits per word: 8 max speed: 500000 Hz (500 kHz) [ 906.314953] kavya : spi phase [ 906.334881] kavya : spi polarity [ 906.355262] kavya : spi mode 0 [ 906.355268] kavya : select the slave TX | 00 19 00 00 00 __ __ __ __ __ __ __ __ __ __ __ __ __ __ __ __ __ __ __ __ __ __ __ __ __ __ __ |…| RX | 01 02 03 07 D0 __ __ __ __ __ __ __ __ __ __ __ __ __ __ __ __ __ __ __ __ __ __ __ __ __ __ __ |…| wiznet driver logs: [ 206.463853] WIZNET : data is 65535 Please do help me on this. Regards, Kavya .

Eugeny · Answer

Kavya1: TX | 00 19 00 00 00 __ __ __ __ __ __ __ __ __ __ __ __ __ __ __ __ __ __ __ __ __ __ __ __ __ __ __ |…| RX | 01 02 03 07 D0 __ __ __ __ __ __ __ __ __ __ __ __ __ __ __ __ __ __ __ __ __ __ __ __ __ __ __ |…| Does it mean that SPI is functioning correctly? Track how data is being passed till it displays Kavya1: [ 206.463853] WIZNET : data is 65535

Kavya1 · Answer

As per our observation spidev_test reading the actual value from the slave device, we will think like spi is functioning correctly. When i probe the data line (MISO), getting FFFF find the attached oscilloscope signal below. IMG202306121629291920×1083 200 KB Please share the compilation procedure for ioLibrary .