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    SubjectRe: [PATCH] serial: serial_txx9 driver update
    >>>>> On Mon, 23 Jan 2006 09:57:00 +0000, Russell King <> said:
    >> - if (disr & TXX9_SIDISR_UOER)
    >> + if (disr & TXX9_SIDISR_UOER) {
    >> up-> port.icount.overrun++;
    >> + /*
    >> + * The receiver read buffer still hold
    >> + * a char which caused overrun.
    >> + * Ignore next char by adding RFDN_MASK
    >> + * to ignore_status_mask temporarily.
    >> + */
    >> + next_ignore_status_mask |=
    >> + }

    rmk> I'm not sure what you mean here.

    rmk> If we successfully received the string ABCDEFGH, and the next character
    rmk> to be received (I) causes an overrun condition, what happens in the
    rmk> case that overruns are not ignored?

    In this case, I will read ABCDEFG without errors, and then I with an overrun

    rmk> Will you read ABCDEFG without any errors from the UART, and then H with
    rmk> an overrun error? If so, you should pass to the TTY layer ABCDEFGH and
    rmk> then a NUL character with TTY_OVERRUN set. Note that uart_insert_char()
    rmk> does this for you.

    Yes, in this case I will read ABCDEFG without error, and then H with
    an overrun error. But the UART still hold "I" in its "read buffer".
    The "read buffer" is exist outside the receiver FIFO. So if 'J' comes
    in later, I will read "IJ". There is no way to clear the "read
    buffer" except resetting the UART.

    Resetting the whole UART is too intrusive, so I chose a way in the
    patch (Ignore just next one char after an overrun error.)

    Atsushi Nemoto
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