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The low-level uart driver may modify termios settings to override settings that are not compatible with the uart, such as CRTSCTS. Thus, callers of the low-level uart driver's set_termios() method must hold termios_rwsem write lock to prevent concurrent access to termios, in case such override occurs. The termios_rwsem lock requirement does not extend to console setup (ie., uart_set_options), as console setup cannot race with tty operations. Nor does this lock requirement extend to functions which cannot be concurrent with tty ioctls (ie., uart_port_startup() and uart_resume_port()). Further, always claim the port mutex to protect hardware re-reprogramming in the set_termios() uart driver method. Note this is unnecessary for console initialization in uart_set_options() which cannot be concurrent with other uart operations. Signed-off-by: Peter Hurley <peter@hurleysoftware.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> |
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00-INDEX | ||
driver | ||
moxa-smartio | ||
n_gsm.txt | ||
README.cycladesZ | ||
rocket.txt | ||
serial-rs485.txt | ||
tty.txt |
The Cyclades-Z must have firmware loaded onto the card before it will operate. This operation should be performed during system startup, The firmware, loader program and the latest device driver code are available from Cyclades at ftp://ftp.cyclades.com/pub/cyclades/cyclades-z/linux/