[PATCH 2.4] serial closing_wait and close_delay

From: Ian Abbott (abbotti_at_mev.co.uk)
Date: 11/30/04

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    Date:	Tue, 30 Nov 2004 19:06:02 +0000
To: Marcelo Tosatti <marcelo.tosatti@cyclades.com>

    Dear Marcelo,

    This patch should fix various problems with the closing_wait and
    close_delay serial parameters, but I can only test the standard serial
    driver.

    There are various scaling problems when HZ != 100:

    * In several drivers, the values set by TIOCSSERIAL are scaled by
    HZ/100, but the values got by TIOCGSERIAL are not scaled back.

    * Invariably, the scaled closing_wait value is compared with an unscaled
    constant ASYNC_CLOSING_WAIT_NONE or the same value by another name
    (depending on the specific driver).

    My patch stores the values set by TIOCSSERIAL without scaling and scales
    the values by HZ/100 at the point of use. (This is not as bad as it
    sounds, as each value is scaled once per 'close'.) There seems to be a
    general consensus amongst the serial drivers that the closing_wait and
    close_delay values from the user are in units of .01 seconds.

    There is another problem, not related to HZ scaling:

    * In several drivers, the closing_wait and close_delay values are
    written to a struct serial_state by TIOCSSERIAL, but the values used in
    the close routine are read from a struct async_struct, with no code to
    transfer of values between the two structures. My patch ignores the
    members in struct async_struct and uses the values from struct serial_state.

    -- Ian.

    Signed-off-by: Ian Abbott <abbotti@mev.co.uk>

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