RTCan missing frames

[Johannes Holtz]

Am 11.02.19 um 12:26 schrieb Wolfgang Grandegger:
> Hello,
>
> Am 11.02.19 um 10:16 schrieb Johannes Holtz via Xenomai:
>> Hi,
>>
>> In my application i set up a RTCAN socket and a pair of rt-threads. One
>> to read and one to write. Writing works perfectly and I receive answers
>> in the initial phase of the program.
>>
>> In particular I send CANopen NMT messages out and receive the responses
>> from the other Nodes in the Network.
>>
>> 2019-02-11 09:52:13.309[       500][    CAN TX] > NMT Node 0:0:
>> CAN ID 0x000 FC 0x0 DLC 2
>>          0       82 00
>> 2019-02-11 09:52:13.310[       503][    CAN RX] > NMT Error Control Node
>> 0:8:
>> CAN ID 0x708 FC 0xe DLC 1
>>          0       00
>> 2019-02-11 09:52:13.311[       503][    CAN RX] > NMT Error Control Node
>> 0:9:
>> CAN ID 0x709 FC 0xe DLC 1
>>          0       00
>> 2019-02-11 09:52:13.317[       509][    CAN RX] > NMT Error Control Node
>> 0:3:
>> CAN ID 0x703 FC 0xe DLC 1
>>          0       00
>> 2019-02-11 09:52:13.317[       509][    CAN RX] > NMT Error Control Node
>> 0:4:
>> CAN ID 0x704 FC 0xe DLC 1
>>          0       00
>> 2019-02-11 09:52:13.317[       509][    CAN RX] > NMT Error Control Node
>> 0:5:
>> CAN ID 0x705 FC 0xe DLC 7
>>          0       00 06 07 00
>>          4       00 01 01
>> 2019-02-11 09:52:13.317[       509][    CAN RX] > NMT Node 0:0:
>> CAN ID 0x000 FC 0x0 DLC 3
>>          0       07 00 00
>> 2019-02-11 09:52:13.326[       519][    CAN RX] > TIME Node 0:1:
>> CAN ID 0x101 FC 0x2 DLC 0
>>
>> As you can see, I capture 7 frames. However, the RX count from
>> /proc/rtcan/devices is 10.
>>
>> If I send specific SDO requests to one of the node which have answered I
>> don't capture a response but the RX count increases and rtcanrecv
>> program captures the correct response. Only my application's read
>> doesn't return.
> Then there seem to be a problem with the read in you application. Can
> you show use the related code?
>
> Wolfgang.

Here is the main function of the rx thread. This will be executed every 1ms.

void can_rx_run(rt_thread_data_t *rt_data) {
     can_thread_data_t *data = (can_thread_data_t *) rt_data->data;
     data->time++;
     static can_frame_t frame_buffer[RX_BUF_SZ];
     static can_frame_t *frame   = NULL;
     static can_bus_t *bus       = NULL;
     int bytes = 1, ret, buf_i = 0;
     uint32_t bus_idx = 0;
     if ((data->time > 10)&& (data->time%2)) {
         bytes       = 1;
         for (bus_idx = 0; bus_idx < data->n_buses; bus_idx++) {
             bus     = &data->buses[bus_idx];
             if(!bus->ready) continue;
             while (bytes > 0 && (buf_i<2)) {
                 frame   = &frame_buffer[buf_i];
                 memset(frame, 0, sizeof (*frame));
                 bytes   = rt_dev_recv(bus->socket, frame, sizeof 
(*frame), MSG_DONTWAIT);
                 if (bytes < 0) {
                     if ((bytes != -ETIMEDOUT) && (bytes != -EAGAIN)) {
                         rtlog(data->log, data->time, LOG_TAG_ERROR, 
"Connection ended unexpected ret %d errno %d", bytes);
                     }else{
                         bytes = 1;
                     }
                     break;
                 } else if (bytes == 0) {
                     rtlog(data->log, data->time, LOG_TAG_ERROR, "CAN 
Bus Connection closed by peer");
                     break;
                 }
                 // move pointer forward for the next frame
                 buf_i = (buf_i + 1) % RX_BUF_SZ;

                 log_frame(data->log, data->time, frame, bus_idx);
                 ret = check_frame_integrity(data->log, data->time, frame);
                 if (ret) {
                     rtlog(data->log, data->time, LOG_TAG_ERROR,
                           "Frame didn't pass integrity check %d", ret);
                     continue;
                 }
                 ret = process_frame(data->ipc_socket, frame, bus_idx);
                 if (ret < 0) {
                     rtlog(data->log, data->time, LOG_TAG_ERROR,
                           "failed to accept RX CAN frame %d from Node %u",
                           ret);
                 }
             }
         }
     }
}