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`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","","\t# insmod parport","","to load the generic parport code. You then must load the","architecture-dependent code with (for example):","","\t# 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.","","","KMod","----","","If you use kmod, you will find it useful to edit /etc/modprobe.conf.","Here is an example of the lines that need to be added:","","\talias parport_lowlevel parport_pc","\toptions parport_pc io=0x378,0x278 irq=7,auto","","KMod will then automatically 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:","","\tparport0: 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:","","\tparport=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","","","File:\t\tContents:","","devices/active\tA list of the device drivers using that port. A \"+\"","\t\twill appear by the name of the device currently using","\t\tthe port (it might not appear against any). The","\t\tstring \"none\" means that there are no device drivers","\t\tusing that port.","","base-addr\tParallel port's base address, or addresses if the port","\t\thas more than one in which case they are separated","\t\twith tabs. These values might not have any sensible","\t\tmeaning for some ports.","","irq\t\tParallel port's IRQ, or -1 if none is being used.","","dma\t\tParallel port's DMA channel, or -1 if none is being","\t\tused.","","modes\t\tParallel port's hardware modes, comma-separated,","\t\tmeaning:","","\t\tPCSPP\t\tPC-style SPP registers are available.","\t\tTRISTATE\tPort is bidirectional.","\t\tCOMPAT\t\tHardware acceleration for printers is","\t\t\t\tavailable and will be used.","\t\tEPP\t\tHardware acceleration for EPP protocol","\t\t\t\tis available and will be used.","\t\tECP\t\tHardware acceleration for ECP protocol","\t\t\t\tis available and will be used.","\t\tDMA\t\tDMA is available and will be used.","","\t\tNote that the current implementation will only take","\t\tadvantage of COMPAT and ECP modes if it has an IRQ","\t\tline to use.","","autoprobe\tAny IEEE-1284 device ID information that has been","\t\tacquired from the (non-IEEE 1284.3) device.","","autoprobe[0-3]\tIEEE 1284 device ID information retrieved from","\t\tdaisy-chain devices that conform to IEEE 1284.3.","","spintime\tThe number of microseconds to busy-loop while waiting","\t\tfor the peripheral to respond. You might find that","\t\tadjusting this improves performance, depending on your","\t\tperipherals. This is a port-wide setting, i.e. it","\t\tapplies to all devices on a particular port.","","timeslice\tThe number of milliseconds that a device driver is","\t\tallowed to keep a port claimed for. This is advisory,","\t\tand driver can ignore it if it must.","","default/*\tThe defaults for spintime and timeslice. When a new","\t\tport is\tregistered, it picks up the default spintime.","\t\tWhen a new device is registered, it picks up the","\t\tdefault 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:","","\t# insmod lp parport=0,2","","or on the LILO command line:","","\tlp=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:","","o polling","o interrupt-driven, protocol in software","o interrupt-driven, protocol in hardware using PIO","o 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_PARPORT_PC_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"],"stylingDirectives":[[],[],[],[],[],[],[],[],[],[],[],[],[],[],[],[],[],[],[],[],[],[],[],[],[],[],[],[],[],[],[],[],[],[],[],[],[],[],[],[],[],[],[],[],[],[],[],[],[],[],[],[],[],[],[],[],[],[],[],[],[],[],[],[],[],[],[],[],[],[],[],[],[],[],[],[],[],[],[],[],[],[],[],[],[],[],[],[],[],[],[],[],[],[],[],[],[],[],[],[],[],[],[],[],[],[],[],[],[],[],[],[],[],[],[],[],[],[],[],[],[],[],[],[],[],[],[],[],[],[],[],[],[],[],[],[],[],[],[],[],[],[],[],[],[],[],[],[],[],[],[],[],[],[],[],[],[],[],[],[],[],[],[],[],[],[],[],[],[],[],[],[],[],[],[],[],[],[],[],[],[],[],[],[],[],[],[],[],[],[],[],[],[],[],[],[],[],[],[],[],[],[],[],[],[],[],[],[],[],[],[],[],[],[],[],[],[],[],[],[],[],[],[],[],[],[],[],[],[],[],[],[],[],[],[],[],[],[],[],[],[],[],[],[],[],[],[],[],[],[],[],[],[],[],[],[],[],[],[],[],[],[],[],[],[],[],[],[]],"colorizedLines":null,"csv":null,"csvError":null,"dependabotInfo":{"showConfigurationBanner":false,"configFilePath":null,"networkDependabotPath":"/torvalds/linux/network/updates","dismissConfigurationNoticePath":"/settings/dismiss-notice/dependabot_configuration_notice","configurationNoticeDismissed":null},"displayName":"parport.txt","displayUrl":"https://github.com/torvalds/linux/blob/v2.6.36-rc4/Documentation/parport.txt?raw=true","headerInfo":{"blobSize":"8.76 KB","deleteTooltip":"You must be signed in to make or propose changes","editTooltip":"You must be signed in to make or propose changes","ghDesktopPath":null,"isGitLfs":false,"onBranch":false,"shortPath":"93a7cee","siteNavLoginPath":"/login?return_to=https%3A%2F%2Fgithub.com%2Ftorvalds%2Flinux%2Fblob%2Fv2.6.36-rc4%2FDocumentation%2Fparport.txt","isCSV":false,"isRichtext":false,"toc":null,"lineInfo":{"truncatedLoc":"268","truncatedSloc":"202"},"mode":"file"},"image":false,"isCodeownersFile":null,"isPlain":false,"isValidLegacyIssueTemplate":false,"issueTemplate":null,"discussionTemplate":null,"language":"Text","languageID":372,"large":false,"planSupportInfo":{"repoIsFork":null,"repoOwnedByCurrentUser":null,"requestFullPath":"/torvalds/linux/blob/v2.6.36-rc4/Documentation/parport.txt","showFreeOrgGatedFeatureMessage":null,"showPlanSupportBanner":null,"upgradeDataAttributes":null,"upgradePath":null},"publishBannersInfo":{"dismissActionNoticePath":"/settings/dismiss-notice/publish_action_from_dockerfile","releasePath":"/torvalds/linux/releases/new?marketplace=true","showPublishActionBanner":false},"rawBlobUrl":"https://github.com/torvalds/linux/raw/v2.6.36-rc4/Documentation/parport.txt","renderImageOrRaw":false,"richText":null,"renderedFileInfo":null,"shortPath":null,"symbolsEnabled":true,"tabSize":8,"topBannersInfo":{"overridingGlobalFundingFile":false,"globalPreferredFundingPath":null,"showInvalidCitationWarning":false,"citationHelpUrl":"https://docs.github.com/github/creating-cloning-and-archiving-repositories/creating-a-repository-on-github/about-citation-files","actionsOnboardingTip":null},"truncated":false,"viewable":true,"workflowRedirectUrl":null,"symbols":{"timed_out":false,"not_analyzed":true,"symbols":[]}},"copilotInfo":null,"copilotAccessAllowed":false,"csrf_tokens":{"/torvalds/linux/branches":{"post":"MzCDM-iBh4W0xymOT4BuJk_5cuNcnviDL-s6JWsxqd3zvKnAVmKevmUs1JxR-NgA9gjJ3PCFVBKEjKoGz3QmWQ"},"/repos/preferences":{"post":"6EVdhhMeUUlslNa6qsJtVeXIKCKj08j-lDujwWSKOxp3d0id6PoTZStJLhh0o29PFxpUSSFN7c5DkppWG1S1SA"}}},"title":"linux/Documentation/parport.txt at v2.6.36-rc4 ยท torvalds/linux"}