4. QserialPortInfo::availablePorts() do not give information about „/dev/ttyGS0“

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QserialPortInfo::availablePorts() do not give information about „/dev/ttyGS0“


  • Dear Developers,

    On my embedded platform (Beaglebone black) USB port is emulated as Serial port „/dev/ttyGS0“.

    But when I try to scan available serial ports on my embedded platform using „QserialPortInfo::availablePorts()“.

    Then in output I do not get any information about emulated Serial Port „/dev/ttyGS0“. Whereas

    „QserialPortInfo::availablePorts()“ was successful in detecting other serial port „ttyS0“ (not emulated from USB) on my embedded platform.

    So please inform me why „QserialPortInfo::availablePorts()“ do not give any information about /dev/ttyGS0“ port ?

    Kindly inform me if you need any other information from me.

    Many thanks..

    0
  • Lifetime Qt Champion

    Hi,

    That might be dependent on what version of Qt you are using. Which is it ? And what Linux distribution are you running ?

    0

  • Hello @SGaist

    Thank you very much for fast reply.

    Version of Qt is : 5.7.1 and linux distribution I am using is given below.

    root@beaglebone:/home/root# uname -a
Linux beaglebone 4.14.71-ti-r80 #1 SMP PREEMPT Fri Oct 5 23:50:11 UTC 2018 armvx
root@beaglebone:/home/root# cat /etc/os-release
PRETTY_NAME="Debian GNU/Linux 9 (stretch)"
NAME="Debian GNU/Linux"
VERSION_ID="9"
VERSION="9 (stretch)"
ID=debian
HOME_URL="https://www.debian.org/"
SUPPORT_URL="https://www.debian.org/support"
BUG_REPORT_URL="https://bugs.debian.org/"

    Please inform me if you need any other information from me.

    Thanks :)

    0
  • Lifetime Qt Champion

    It's a bit an old version but IIRC, it should be good to access the device...

    Can you check if it is a symlink ?

    0 1 Reply
  • Lifetime Qt Champion

    @kuzulis can you help here?

    0

  • @saurabh162 said in QserialPortInfo::availablePorts() do not give information about „/dev/ttyGS0“:

    /dev/ttyGS0

    Try latest version of Qt as 5.7.1 is too old (at least try v 5.9). And then we be investigate an issue.

    UPD:

    1. do you have the /dev/ttyGS0 in a filesystem in reality?
    2. try this comamnd: udevadm info --name=/dev/ttyGS0 and paste an output here.
    3. try compile and run the following code (what is it return? true/false?):
    #include <linux/serial.h> 

bool foo()
{
    const mode_t flags = O_RDWR | O_NONBLOCK | O_NOCTTY;
    const int fd = ::open("/dev/ttyGS0", flags);
    if (fd != -1) {
        struct serial_struct serinfo;
        const int retval = ::ioctl(fd, TIOCGSERIAL, &serinfo);
        ::close(fd);
        if (retval != -1 && serinfo.type != PORT_UNKNOWN)
            return true;
    }
    return false;
}
    2

  • Hello @SGaist , @aha_1980, @kuzulis

    Thank you very much for your help

    I will surely install Qt5.9 on my Beaglebone black and compile cross tool chain on host machine corresponding to it but at this moment I cannot do it due to other priorities.

    Following are the answers to questions asked by @kuzulis

    1. do you have the /dev/ttyGS0 in a filesystem in reality?

    Ans) Yes, I have it and I am manually opening this port using following code in Beagebone black and doing communication which is also working perfectly.

    isBBBSerialOpened = co2SerialPortobject.OpenConfigureCO2HW("/dev/ttyGS0" ,
                                         co2SerialPortobject.ReadWrite,
                                         co2SerialPortobject.Baud9600,
                                         co2SerialPortobject.Data8,
                                         co2SerialPortobject.NoParity,
                                         co2SerialPortobject.OneStop,
                                         co2SerialPortobject.NoFlowControl);
    1. try this comamnd: udevadm info --name=/dev/ttyGS0 and paste an output here ?

    Ans)

    
udevadm info --name=/dev/ttyGS0
P: /devices/virtual/tty/ttyGS0
N: ttyGS0
E: DEVNAME=/dev/ttyGS0
E: DEVPATH=/devices/virtual/tty/ttyGS0
E: MAJOR=243
E: MINOR=0
E: SUBSYSTEM=tty
E: TAGS=:systemd:
E: USEC_INITIALIZED=32563390
E: net.ifnames=0

    Q) try compile and run the following code (what is it return? true/false?): ?

    #include <linux/serial.h> 

bool foo()
{
    const mode_t flags = O_RDWR | O_NONBLOCK | O_NOCTTY;
    const int fd = ::open("/dev/ttyGS0", flags);
    if (fd != -1) {
        struct serial_struct serinfo;
        const int retval = ::ioctl(fd, TIOCGSERIAL, &serinfo);
        ::close(fd);
        if (retval != -1 && serinfo.type != PORT_UNKNOWN)
            return true;
    }
    return false;
}

    Ans) After compiling above code I got following errors

    test.c:3:1: error: unknown type name ��‘bool��’
 bool foo()
 ^~~~
test.c: In function ��‘foo��’:
test.c:5:11: error: unknown type name ��‘mode_t��’
     const mode_t flags = O_RDWR | O_NONBLOCK | O_NOCTTY;
           ^~~~~~
test.c:5:26: error: ��‘O_RDWR��’ undeclared (first use in this function)
     const mode_t flags = O_RDWR | O_NONBLOCK | O_NOCTTY;
                          ^~~~~~
test.c:5:26: note: each undeclared identifier is reported only once for each function it appears in
test.c:5:35: error: ��‘O_NONBLOCK��’ undeclared (first use in this function)
     const mode_t flags = O_RDWR | O_NONBLOCK | O_NOCTTY;
                                   ^~~~~~~~~~
test.c:5:48: error: ��‘O_NOCTTY��’ undeclared (first use in this function)
     const mode_t flags = O_RDWR | O_NONBLOCK | O_NOCTTY;
                                                ^~~~~~~~
test.c:6:20: error: expected expression before ��‘:��’ token
     const int fd = ::open("/dev/ttyGS0", flags);
                    ^
test.c:9:28: error: expected expression before ��‘:��’ token
         const int retval = ::ioctl(fd, TIOCGSERIAL, &serinfo);
                            ^
test.c:10:9: error: expected expression before ��‘:��’ token
         ::close(fd);
         ^
test.c:12:20: error: ��‘true��’ undeclared (first use in this function)
             return true;
                    ^~~~
test.c:14:12: error: ��‘false��’ undeclared (first use in this function)
     return false;

    Please inform me if you need any other information from me.

    many thanks :)

    0 1 Reply

  • @SGaist said in QserialPortInfo::availablePorts() do not give information about „/dev/ttyGS0“:

    IIRC

    Hello @SGaist, Thank you very much. I checked but "ttyGS0" is not symlink following the command I used to check it.

    root@beaglebone:/dev# ls -l ttyGS0
crw--w---- 1 root tty 243, 0 Apr 17 10:08 ttyGS0
    0
  • Lifetime Qt Champion

    @saurabh162

    For your code: replace bool with int and true with 1 resp. false with 0. Or simply use a C++ instead a C file.

    For the other errors you will need some more includes, Google should help you there.

    1

  • Hello @aha_1980

    Thank you very much for the help ..I will try to compile it again and will update you

    0

  • Hello @aha_1980,

    I have run above function foo() and got

    retval = -1 from following statement

    const int retval = ::ioctl(fd, TIOCGSERIAL, &serinfo);

    Additionally when I print value of variable errno after calling above statement, then it comes out to be 25.

    Moreover value of serinfo.type variable is 2(#define PORT_16450 2)

    can you please inform me what can be reasons for it and how can I solve it ?

    I am also trying to solve this problem at my side and will update you if I get any progress.

    Many thanks :)

    0

  • @saurabh162 ,

    Hmm.. Seems, need to debug the QSerialPortInfo class to see what happens there.

    0

  • Please see a fix: https://codereview.qt-project.org/#/c/260832/

    2

  • Hello @kuzulis

    Thank you very much..Can you please inform me how can I apply this fix to my Qt.

    Regards

    Saurabh

    0

  • @saurabh162 said in QserialPortInfo::availablePorts() do not give information about „/dev/ttyGS0“:

    Can you please inform me how can I apply this fix to my Qt.

    Just modify that file in a qtserialport sources and rebuild it. Or, just wait for a next Qt release (seems to 5.12.4).

    2

  • Hello Kuzulis,

    Thanks a lot for your update ...

    I think using latest fixed version of Qt release (seems to 5.12.4) will be better choice. Please inform me, what should I do with this query should I close it or leave it open till I test it with Qt release (seems to 5.12.4).

    Regards Saurabh

    0
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