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    SubjectRe: imx: RS-485 problems during TX, maybe DMA related
    Hi Clemens,

    On Wed, Jan 4, 2017 at 2:00 PM, Clemens Gruber
    <clemens.gruber@pqgruber.com> wrote:
    > Hi,
    >
    > I observed odd behavior of the current tty/serial/imx.c driver in RS-485
    > mode.
    >
    > RX works fine, but TX does not: When sending data, it arrives multiple

    I am also trying to get rs485 in half-duplex mode to work on mx6dl
    with kernel 4.9.

    RX also works for me, but TX does not.

    On my board it is the MX6QDL_PAD_CSI0_DAT16__UART4_RTS_B pin that
    controls the rs485 transceiver flow, but I do not
    see RTS to toggle to 1 during transmit. It stays always at 0.

    I see you use CTS pin instead, but I thought RTS pin should be used.

    On my userspace application I have:

    /* enable RS485 mode: */
    rs485conf.flags |= SER_RS485_ENABLED;

    /* set logical level for RTS pin equal to 1 when sending: */
    rs485conf.flags |= SER_RS485_RTS_ON_SEND;

    /* set logical level for RTS pin equal to 0 after sending: */
    rs485conf.flags &= ~(SER_RS485_RTS_AFTER_SEND);

    Any ideas as to how to make RTS go to one so that the data can go
    through the rs485 transceiver?

    Thanks

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