+++ /dev/null
-Parport
-+++++++
-
-The ``parport`` code provides parallel-port support under Linux. This
-includes the ability to share one port between multiple device
-drivers.
-
-You can pass parameters to the ``parport`` code to override its automatic
-detection of your hardware. This is particularly useful if you want
-to use IRQs, since in general these can't be autoprobed successfully.
-By default IRQs are not used even if they **can** be probed. This is
-because there are a lot of people using the same IRQ for their
-parallel port and a sound card or network card.
-
-The ``parport`` code is split into two parts: generic (which deals with
-port-sharing) and architecture-dependent (which deals with actually
-using the port).
-
-
-Parport as modules
-==================
-
-If you load the `parport`` code as a module, say::
-
- # insmod parport
-
-to load the generic ``parport`` code. You then must load the
-architecture-dependent code with (for example)::
-
- # insmod parport_pc io=0x3bc,0x378,0x278 irq=none,7,auto
-
-to tell the ``parport`` code that you want three PC-style ports, one at
-0x3bc with no IRQ, one at 0x378 using IRQ 7, and one at 0x278 with an
-auto-detected IRQ. Currently, PC-style (``parport_pc``), Sun ``bpp``,
-Amiga, Atari, and MFC3 hardware is supported.
-
-PCI parallel I/O card support comes from ``parport_pc``. Base I/O
-addresses should not be specified for supported PCI cards since they
-are automatically detected.
-
-
-modprobe
---------
-
-If you use modprobe , you will find it useful to add lines as below to a
-configuration file in /etc/modprobe.d/ directory::
-
- alias parport_lowlevel parport_pc
- options parport_pc io=0x378,0x278 irq=7,auto
-
-modprobe will load ``parport_pc`` (with the options ``io=0x378,0x278 irq=7,auto``)
-whenever a parallel port device driver (such as ``lp``) is loaded.
-
-Note that these are example lines only! You shouldn't in general need
-to specify any options to ``parport_pc`` in order to be able to use a
-parallel port.
-
-
-Parport probe [optional]
-------------------------
-
-In 2.2 kernels there was a module called ``parport_probe``, which was used
-for collecting IEEE 1284 device ID information. This has now been
-enhanced and now lives with the IEEE 1284 support. When a parallel
-port is detected, the devices that are connected to it are analysed,
-and information is logged like this::
-
- parport0: Printer, BJC-210 (Canon)
-
-The probe information is available from files in ``/proc/sys/dev/parport/``.
-
-
-Parport linked into the kernel statically
-=========================================
-
-If you compile the ``parport`` code into the kernel, then you can use
-kernel boot parameters to get the same effect. Add something like the
-following to your LILO command line::
-
- parport=0x3bc parport=0x378,7 parport=0x278,auto,nofifo
-
-You can have many ``parport=...`` statements, one for each port you want
-to add. Adding ``parport=0`` to the kernel command-line will disable
-parport support entirely. Adding ``parport=auto`` to the kernel
-command-line will make ``parport`` use any IRQ lines or DMA channels that
-it auto-detects.
-
-
-Files in /proc
-==============
-
-If you have configured the ``/proc`` filesystem into your kernel, you will
-see a new directory entry: ``/proc/sys/dev/parport``. In there will be a
-directory entry for each parallel port for which parport is
-configured. In each of those directories are a collection of files
-describing that parallel port.
-
-The ``/proc/sys/dev/parport`` directory tree looks like::
-
- parport
- |-- default
- | |-- spintime
- | `-- timeslice
- |-- parport0
- | |-- autoprobe
- | |-- autoprobe0
- | |-- autoprobe1
- | |-- autoprobe2
- | |-- autoprobe3
- | |-- devices
- | | |-- active
- | | `-- lp
- | | `-- timeslice
- | |-- base-addr
- | |-- irq
- | |-- dma
- | |-- modes
- | `-- spintime
- `-- parport1
- |-- autoprobe
- |-- autoprobe0
- |-- autoprobe1
- |-- autoprobe2
- |-- autoprobe3
- |-- devices
- | |-- active
- | `-- ppa
- | `-- timeslice
- |-- base-addr
- |-- irq
- |-- dma
- |-- modes
- `-- spintime
-
-.. tabularcolumns:: |p{4.0cm}|p{13.5cm}|
-
-======================= =======================================================
-File Contents
-======================= =======================================================
-``devices/active`` A list of the device drivers using that port. A "+"
- will appear by the name of the device currently using
- the port (it might not appear against any). The
- string "none" means that there are no device drivers
- using that port.
-
-``base-addr`` Parallel port's base address, or addresses if the port
- has more than one in which case they are separated
- with tabs. These values might not have any sensible
- meaning for some ports.
-
-``irq`` Parallel port's IRQ, or -1 if none is being used.
-
-``dma`` Parallel port's DMA channel, or -1 if none is being
- used.
-
-``modes`` Parallel port's hardware modes, comma-separated,
- meaning:
-
- - PCSPP
- PC-style SPP registers are available.
-
- - TRISTATE
- Port is bidirectional.
-
- - COMPAT
- Hardware acceleration for printers is
- available and will be used.
-
- - EPP
- Hardware acceleration for EPP protocol
- is available and will be used.
-
- - ECP
- Hardware acceleration for ECP protocol
- is available and will be used.
-
- - DMA
- DMA is available and will be used.
-
- Note that the current implementation will only take
- advantage of COMPAT and ECP modes if it has an IRQ
- line to use.
-
-``autoprobe`` Any IEEE-1284 device ID information that has been
- acquired from the (non-IEEE 1284.3) device.
-
-``autoprobe[0-3]`` IEEE 1284 device ID information retrieved from
- daisy-chain devices that conform to IEEE 1284.3.
-
-``spintime`` The number of microseconds to busy-loop while waiting
- for the peripheral to respond. You might find that
- adjusting this improves performance, depending on your
- peripherals. This is a port-wide setting, i.e. it
- applies to all devices on a particular port.
-
-``timeslice`` The number of milliseconds that a device driver is
- allowed to keep a port claimed for. This is advisory,
- and driver can ignore it if it must.
-
-``default/*`` The defaults for spintime and timeslice. When a new
- port is registered, it picks up the default spintime.
- When a new device is registered, it picks up the
- default timeslice.
-======================= =======================================================
-
-Device drivers
-==============
-
-Once the parport code is initialised, you can attach device drivers to
-specific ports. Normally this happens automatically; if the lp driver
-is loaded it will create one lp device for each port found. You can
-override this, though, by using parameters either when you load the lp
-driver::
-
- # insmod lp parport=0,2
-
-or on the LILO command line::
-
- lp=parport0 lp=parport2
-
-Both the above examples would inform lp that you want ``/dev/lp0`` to be
-the first parallel port, and /dev/lp1 to be the **third** parallel port,
-with no lp device associated with the second port (parport1). Note
-that this is different to the way older kernels worked; there used to
-be a static association between the I/O port address and the device
-name, so ``/dev/lp0`` was always the port at 0x3bc. This is no longer the
-case - if you only have one port, it will default to being ``/dev/lp0``,
-regardless of base address.
-
-Also:
-
- * If you selected the IEEE 1284 support at compile time, you can say
- ``lp=auto`` on the kernel command line, and lp will create devices
- only for those ports that seem to have printers attached.
-
- * If you give PLIP the ``timid`` parameter, either with ``plip=timid`` on
- the command line, or with ``insmod plip timid=1`` when using modules,
- it will avoid any ports that seem to be in use by other devices.
-
- * IRQ autoprobing works only for a few port types at the moment.
-
-Reporting printer problems with parport
-=======================================
-
-If you are having problems printing, please go through these steps to
-try to narrow down where the problem area is.
-
-When reporting problems with parport, really you need to give all of
-the messages that ``parport_pc`` spits out when it initialises. There are
-several code paths:
-
-- polling
-- interrupt-driven, protocol in software
-- interrupt-driven, protocol in hardware using PIO
-- interrupt-driven, protocol in hardware using DMA
-
-The kernel messages that ``parport_pc`` logs give an indication of which
-code path is being used. (They could be a lot better actually..)
-
-For normal printer protocol, having IEEE 1284 modes enabled or not
-should not make a difference.
-
-To turn off the 'protocol in hardware' code paths, disable
-``CONFIG_PARPORT_PC_FIFO``. Note that when they are enabled they are not
-necessarily **used**; it depends on whether the hardware is available,
-enabled by the BIOS, and detected by the driver.
-
-So, to start with, disable ``CONFIG_PARPORT_PC_FIFO``, and load ``parport_pc``
-with ``irq=none``. See if printing works then. It really should,
-because this is the simplest code path.
-
-If that works fine, try with ``io=0x378 irq=7`` (adjust for your
-hardware), to make it use interrupt-driven in-software protocol.
-
-If **that** works fine, then one of the hardware modes isn't working
-right. Enable ``CONFIG_FIFO`` (no, it isn't a module option,
-and yes, it should be), set the port to ECP mode in the BIOS and note
-the DMA channel, and try with::
-
- io=0x378 irq=7 dma=none (for PIO)
- io=0x378 irq=7 dma=3 (for DMA)
-
-----------
-
-philb@gnu.org
-tim@cyberelk.net
projects / linux-2.6-block.git / blobdiff