[lkml]   [2007]   [Jul]   [27]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
Messages in this thread
    SubjectRe: serial flow control appears broken
    Maciej W. Rozycki wrote:

    >On Thu, 26 Jul 2007, Lee Howard wrote:
    >>If the application were to use TIOCM_RTS how would it know when to apply it or
    >>not? Is there some approach that the application could take to manage flow
    >>control on the serial port? What about software flow control? Does the
    > Well, an application could negate RTS when it receives a character and
    >is running out of resources for further processing of incoming data.
    > Smarter UARTs may be able to negate RTS themselves based on the amount of
    >data in their receive FIFO. The threshold may be configurable.

    Okay, so let's say we've got a loop around a blocking read on the modem
    file descriptor...

    for (;;) {
    read some data from modem
    process data from modem
    if (end-of-data detected) break;

    Are you suggesting that the application should be using deasserting RTS
    after the read and asserting it before?

    I had previously thought that the control of RTS was something that the
    serial/tty driver was supposed to do independently based on the buffer
    fill. Was I wrong?


    To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
    the body of a message to
    More majordomo info at
    Please read the FAQ at

     \ /
      Last update: 2007-07-27 19:15    [W:0.021 / U:115.756 seconds]
    ©2003-2016 Jasper Spaans. hosted at Digital OceanAdvertise on this site