Could not allocate rx buffer error with Ethernet samples using ENC424J600 with nRF52840

Question

Hi,

I've got a custom board with an ENC424J600 connected to an nRF52840. I started with nRF Connect v2.0.0 but I've since upgraded to the latest (v2.3.0-rc1) to see if it fixed my problem - which it didn't.

I made a custom zephyr "board" based on the nRF52840 devkit files and modified it as needed to add a the enc424j600 to SPI0. I got the http_client demo to connect to a simple unsecure server running on my PC (the TCPIP_Demo.jar app from Microchip) - so the hardware and the basics of adding the mac/phy to my project seems to be good.

My next step is to get it working with something out in the real world - like doing an http get from google or bouncing something off the tcpbin.com echo server. The problem is that when I try to do a DNS lookup with getaddrinfo() I get a "Could not allocate rx buffer" error. I've tried the http_get and the http_client examples with the same result. Fulll RTT output below:

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00> [00:00:00.314,422] <inf> ethdrv: Link down
00> [00:00:00.314,483] <inf> ethdrv: ENC424J600 Initialized
00> [00:00:00.314,758] <inf> ethdrv: Not suspended
00> *** Booting Zephyr OS build v3.2.99-ncs2-rc1 ***
00> [00:00:00.315,032] <inf> net_config: Initializing network
00> [00:00:00.315,063] <inf> net_config: Waiting interface 1 (0x20001338) to be up...
00> [00:00:01.838,989] <inf> ethdrv: Link up
00> [00:00:01.839,233] <inf> ethdrv: 100Mbps
00> [00:00:01.839,233] <inf> ethdrv: full duplex
00> [00:00:01.840,179] <inf> net_config: Interface 1 (0x20001338) coming up
00> [00:00:01.846,527] <inf> net_config: IPv4 address: 192.168.137.2
00> [00:00:07.770,538] <err> ethdrv: Could not allocate rx buffer

It seems like the error is coming from a memory allocation attempt in mem_slab.c.

I've been trying to increase all of the memory sizes I can but either I haven't found the right one to increase, or maybe I'm just not setting them high enough. Here's what I've added so far - with no change in results:

CONFIG_ETH_ENC424J600_RX_THREAD_STACK_SIZE=1536

CONFIG_MEM_SLAB_TRACE_MAX_UTILIZATION=y

CONFIG_HEAP_MEM_POOL_SIZE=1024

CONFIG_MAIN_STACK_SIZE=1536

Please help! This is quite urgent as we need to determine if this hardware solution is solid before we fully commit to this path for manufacturing.

Thanks,

Glen

Glen M · Accepted Answer

I've managed to get this working. Here's what I learned in case someone else is trying to get the Zephyr Ethernet socket samples (specifically http_get) working. 
 
 1) I've been using my Segger J-Link+ with RTT viewer 7.66a to see the debug output, and I found that it stops printing data well before the program was dying. 
 I bought a cheap tp-link managed switch with port mirroring so that I can direct all of the traffic to-from my test board to my work computer and I can see all of the packets with Wireshark. That immediately showed me that I was getting farther in the sample code than I thought I was based on the RTT output. 
 I also changed the code which calls getaddrinfo to look up the IP address to call it in a loop until it's successful rather than bailing out and stopping the sample program at the first failure. 
 I added the following lines to my prj.conf to get the debug info to come out of my debug UART instead:

CONFIG_LOG =y 
 CONFIG_LOG_BACKEND_UART =y

2) The http_get sample to Google by default, but Google no longer supports insecure connections so it fails. So turning TLS on by putting the stuff from overlay-tls.conf into my main prj.conf file got me to the point where I got a response from google. Also, the sample goes to "google.com" which gets you a "permanently moved" response - changing it to "www.google.com" got me a real HTTP GET of the page.

Could not allocate rx buffer error with Ethernet samples using ENC424J600 with nRF52840

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