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01fd45f676
TIOCSSERIAL is a horrid, underspecified, legacy interface which for most serial devices is only useful for setting the close_delay and closing_wait parameters. The closing_wait parameter determines how long to wait for the transfer buffers to drain during close and the default timeout of 30 seconds may not be sufficient at low line speeds. In other cases, when for example flow is stopped, the default timeout may instead be too long. Add generic support for TIOCSSERIAL and TIOCGSERIAL with handling of the three common parameters close_delay, closing_wait and line for the benefit of all USB serial drivers while still allowing drivers to implement further functionality through the existing callbacks. This currently includes a few drivers that report their base baud clock rate even if that is really only of interest when setting custom divisors through the deprecated ASYNC_SPD_CUST interface; an interface which only the FTDI driver actually implements. Some drivers have also been reporting back a fake UART type, something which should no longer be needed and will be dropped by a follow-on patch. Reviewed-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Signed-off-by: Johan Hovold <johan@kernel.org>
Linux kernel
============
There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.
In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``. The formatted documentation can also be read online at:
https://www.kernel.org/doc/html/latest/
There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.
Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.