AM4376: PRU Ethernet solution

Hello Walter,

Apologies for the delayed response, just returned from vacation. The PRU Firmware for generic PRU Ethernet should be bundled in the RT Linux Processor SDK 7.3, which you can download here: https://www.ti.com/tool/PROCESSOR-SDK-AM437X

Regards,

Nick

Please note that there might be some issues with AM335x / AM437x PRU Ethernet on Linux 5.10 that were not on Linux 4.19, see thread https://e2e.ti.com/support/processors-group/processors/f/processors-forum/1021715/am3359-pru-dual-emac-same-packet-repeated-several-times-randomly . If you observe anything strange, let us know so we can work with you on it.

Regards,

Nick

Hello Nick,

many thanks for SDK location.

I've analyzed the device tree for am437x-idk-evm, which contains two PRUETH ports:

 /* Dual-MAC Ethernet application node on PRU-ICSS1 */
 pruss1_eth {
  compatible = "ti,am4376-prueth";
  prus = <&pru1_0>, <&pru1_1>;
  sram = <&ocmcram>;
  interrupt-parent = <&pruss1_intc>;
  mii-rt = <&pruss1_mii_rt>;
  iep = <&pruss1_iep>;
  ecap = <&pruss1_ecap>;

  pinctrl-0 = <&pruss1_eth_default>;
  pinctrl-names = "default";
  interrupts = <20>, <21>;
  interrupt-names = "rx_lre_hp", "rx_lre_lp";

  pruss1_emac0: ethernet-mii0 {
   phy-handle = <&pruss1_eth0_phy>;
   phy-mode = "mii";
   interrupts = <20>;
   interrupt-names = "rx";
   ti,no-half-duplex;
   /* Filled in by bootloader */
   local-mac-address = [00 00 00 00 00 00];
  };

  pruss1_emac1: ethernet-mii1 {
   phy-handle = <&pruss1_eth1_phy>;
   phy-mode = "mii";
   interrupts = <21>;
   interrupt-names = "rx";
   ti,no-half-duplex;
   /* Filled in by bootloader */
   local-mac-address = [00 00 00 00 00 00];
  };
 };

My questions:

* kernel 5.10 uses interrupts like: interrupts = <20 4 4>; with host and channel number. How can I change the device tree ? Which

host & chan numbers have interrupts 20 & 21 ?

* I have only one ICCS1 core: pru1_0 and would like us only mii0. Is it possible without second core: pru1_1 ?

* Do you know about cpsw-switchdev too ? I have some questions to the switch functionality.

Hello Walter,

I just realized I misinterpreted your request. Linux Processor SDK 7.3 uses Linux kernel 5.4. We just released Linux Processor SDK 8.0 (Which uses Linux kernel 5.10) for AM64x today. We will release an AM335x and AM437x version of Linux Processor SDK 8.x (with Linux kernel 5.10) at some point, but it will not be for a while.

Regards,

Nick

Hello Nick,

no problem. We will wait for complete SDK 8.x for AM437x.

To my questions before:

Only this: I have only one ICCS1 core: pru1_0 and would like us only mii0. Is it possible without second core: pru1_1 ?

Other questions are resolved.

Best Regards

Walter

Hello Walter,

I missed your last question, apologies for the delayed response.

Yes, we added the possibility of using a single PRU Ethernet port in Linux 4.14, and I would expect it to still work in Linux 5.4 / Linux 5.10.

These threads document how to get single PRU Ethernet working on Linux 4.14 & Linux 4.19:
https://e2e.ti.com/support/processors-group/processors/f/processors-forum/802388/linux-am5726-single-pru-ethernet-mii
https://e2e.ti.com/support/processors-group/processors/f/processors-forum/852126/am5728-pru-ethernet-driver-error (discusses how to modify device tree).

Note that TI has not tested running PRU applications on the PRU that is not controlling an Ethernet port. 

Regards,

Nick