Revision 474095e46cd14421821da3201a9fd6a4c070996b authored by Linus Torvalds on 24 April 2015, 16:28:01 UTC, committed by Linus Torvalds on 24 April 2015, 16:28:01 UTC
Pull md updates from Neil Brown: "More updates that usual this time. A few have performance impacts which hould mostly be positive, but RAID5 (in particular) can be very work-load ensitive... We'll have to wait and see. Highlights: - "experimental" code for managing md/raid1 across a cluster using DLM. Code is not ready for general use and triggers a WARNING if used. However it is looking good and mostly done and having in mainline will help co-ordinate development. - RAID5/6 can now batch multiple (4K wide) stripe_heads so as to handle a full (chunk wide) stripe as a single unit. - RAID6 can now perform read-modify-write cycles which should help performance on larger arrays: 6 or more devices. - RAID5/6 stripe cache now grows and shrinks dynamically. The value set is used as a minimum. - Resync is now allowed to go a little faster than the 'mininum' when there is competing IO. How much faster depends on the speed of the devices, so the effective minimum should scale with device speed to some extent" * tag 'md/4.1' of git://neil.brown.name/md: (58 commits) md/raid5: don't do chunk aligned read on degraded array. md/raid5: allow the stripe_cache to grow and shrink. md/raid5: change ->inactive_blocked to a bit-flag. md/raid5: move max_nr_stripes management into grow_one_stripe and drop_one_stripe md/raid5: pass gfp_t arg to grow_one_stripe() md/raid5: introduce configuration option rmw_level md/raid5: activate raid6 rmw feature md/raid6 algorithms: xor_syndrome() for SSE2 md/raid6 algorithms: xor_syndrome() for generic int md/raid6 algorithms: improve test program md/raid6 algorithms: delta syndrome functions raid5: handle expansion/resync case with stripe batching raid5: handle io error of batch list RAID5: batch adjacent full stripe write raid5: track overwrite disk count raid5: add a new flag to track if a stripe can be batched raid5: use flex_array for scribble data md raid0: access mddev->queue (request queue member) conditionally because it is not set when accessed from dm-raid md: allow resync to go faster when there is competing IO. md: remove 'go_faster' option from ->sync_request() ...
parport.txt
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
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:
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
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