parport_yield(9) [suse man page]

PARPORT_YIELD(9)					       Parallel Port Devices						  PARPORT_YIELD(9)

NAME

       parport_yield - relinquish a parallel port temporarily

SYNOPSIS

       int parport_yield(struct pardevice * dev);

ARGUMENTS

       dev
	   a device on the parallel port

DESCRIPTION

       This function relinquishes the port if it would be helpful to other drivers to do so. Afterwards it tries to reclaim the port using
       parport_claim, and the return value is the same as for parport_claim. If it fails, the port is left unclaimed and it is the driver's
       responsibility to reclaim the port.

       The parport_yield and parport_yield_blocking functions are for marking points in the driver at which other drivers may claim the port and
       use their devices. Yielding the port is similar to releasing it and reclaiming it, but is more efficient because no action is taken if
       there are no other devices needing the port. In fact, nothing is done even if there are other devices waiting but the current device is
       still within its "timeslice". The default timeslice is half a second, but it can be adjusted via the /proc interface.

COPYRIGHT

Kernel Hackers Manual 2.6.					     July 2010							  PARPORT_YIELD(9)

LPT(4)							   BSD Kernel Interfaces Manual 						    LPT(4)

NAME

     lpt -- generic printer device driver

SYNOPSIS

     device ppc
     device ppbus
     device lpt

DESCRIPTION

     The current lpt driver is the port of the original lpt driver to the ppbus(4) system.

     One purpose of this port was to allow parallel port sharing with other parallel devices.  Secondly, inb()/outb() calls have been replaced by
     ppbus function calls.  lpt is now arch-independent thanks to the ppbus interface.	See ppbus(4) for more info about the ppbus system.

     The parallel port bus is allocated by lpt when the printer device is opened and released only when the transfer is completed: either when the
     device is closed or when the entire buffer is sent in interrupt driven mode.

     The driver can be configured to be either interrupt-driven, or to poll the printer.  Ports that are configured to be interrupt-driven can be
     switched to polled mode by using the lptcontrol(8) command.

     Depending on your hardware, extended capabilities may be configured with the lptcontrol(8) command.  With an ECP/ISA port, you can take
     advantage of FIFO and DMA.

     In order to retrieve printer info from /dev/lpt0, just apply the cat command to the device.  If the printer supports IEEE1284 nibble mode and
     has data to send to the host, you will get it.

FILES

     /dev/lpt0			       first parallel port driver

SEE ALSO

     ppbus(4), ppc(4), lptcontrol(8)

HISTORY

     This driver replaces the functionality of the lpa driver, which is now defunct.

BUGS

     There are lots of them, especially in cheap parallel port implementations.

     It is only possible to open a lpt port when a printer is connected and on-line, making it impossible to run lptcontrol(8) when there is no
     printer connected.

     This driver could still stand a rewrite.

BSD
								 February 14, 1999							       BSD