NULL pointer passed to sync_rx issue

[AurelienS]

Hello everyone,

I am using the great BladeRF x115 with OpenAirInterface (https://gitlab.eurecom.fr/oai/openairin ... wikis/home), a software to implement LTE networks in SDR.

Before I post this topic, I already have overrun issues with it, but resolved them by decreasing the bandwith (5 MHz to 1.4 MHz).

But now, when I am running the software part responsible of the radio frontend, I get these errors :

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[DEBUG @ sync.c:292] NULL pointer passed to sync_rx
RX failed: Invalid operation or parameter

Can someone explain me what can be the cause ? And, if possible, can someone help me to resolve this issue ?

Here is some informations about my setup, hope it will be sufficient :

- The host : a old (~4 years old) computer (Lenovo X230 tablet) with 4 (real) cores Intel(R) Core(TM) i7-3520M CPU @ 2.90GHz, running Ubuntu 14.04.4 LTS with a low-latency 3.19 (x86_64) kernel. The USB contoller is an Intel Corporation 7 Series/C210 Series Chipset Family USB xHCI Host Controller (rev 04) (prog-if 30 [XHCI]), and according to my researches is not blacklisted.

- The BladeRF hardware version and configuration :

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bladeRF> info

  Serial #:                 4f4e1acb5e1e45ab348665752172cc1f
  VCTCXO DAC calibration:   0x9261
  FPGA size:                115 KLE
  FPGA loaded:              yes
  USB bus:                  2
  USB address:              2
  USB speed:                SuperSpeed
  Backend:                  libusb
  Instance:                 0

bladeRF> version

  bladeRF-cli version:        1.4.0-git-d7b7eb3
  libbladeRF version:         1.7.1-git-d7b7eb3

  Firmware version:           1.9.0
  FPGA version:               0.5.0

The firmware and FPGA are updated by OAI build script using the bladerf ppa.

I use the following configuration for LTE :

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                 downlink_frequency      			      = 2680000000L; // L is ok but I don't know why
                           uplink_frequency_offset 			      = -120000000;
                           N_RB_DL                 			      = 6; // bandwith : 1.4 MHz
                           nb_antennas_tx          			      = 1;
                           nb_antennas_rx          			      = 1; 
			   tx_gain                                                = 60;
			   rx_gain                                                = 120;

- Complete setup : two antennas (they look like a fir or a pine, sorry I don't know a lot about antennas) with a range from 900 MHz to 2600 MHz we can find here (https://www.ettus.com/product/details/LP0965) plugged in the RX and TX port, the bladeRF is connected to the host by a USB 3 cable in a SuperSpeed port (verified using lsusb and the bladerf-cli). Note : the bladeRF is not powered by external power supply (does it need that ?)


I remain at your disposal for other informations,
Thank you a lot,

Aurélien Surier <[email protected]>

[AurelienS]

Hello jinyk,

Thank you for your fast reply.

I think it's more the code callling bladerf_sync_rx passing NULL buffer as you said (I take a look at the code, and found that bladerf_sync_config is called earlier).

I'm about to do a backtrace (but I think It will take some time). Moreover, I will talk about that to OAI developers.

Also, thank you to have confirmed that the USB configuration seems inadequate.

Have a nice day,
Best Regards