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Signed-off-by: Charis Kouzinopoulos <kouzinopoulos@gmail.com>
Signed-off-by: Thibault Le Meur <Thibault.LeMeur@supelec.fr>
Signed-off-by: Takashi Iwai <tiwai@suse.de>
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Signed-off-by: Miklos Szeredi <miklos@szeredi.hu>
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* 'for-linus' of git://brick.kernel.dk/data/git/linux-2.6-block:
[PATCH] block/elevator.c: remove unused exports
[PATCH] splice: fix smaller sized splice reads
[PATCH] Don't inherit ->splice_pipe across forks
[patch] cleanup: use blk_queue_stopped
[PATCH] Document online io scheduler switching
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Update the schedule for the removal of drivers depending on
OBSOLETE_OSS_DRIVER as follows:
- adjust OBSOLETE_OSS_DRIVER dependencie
- from the release of 2.6.16 till the release of 2.6.17:
approx. two months for users to report problems with the ALSA
drivers for the same hardware
- after the release of 2.6.17 (and before 2.6.18):
remove the subset of drivers marked at OBSOLETE_OSS_DRIVER without
known regressions in the ALSA drivers for the same hardware
Additionally, correct some OBSOLETE_OSS_DRIVER dependencies.
A rationale of the changes is in
http://lkml.org/lkml/2006/1/28/135
Signed-off-by: Adrian Bunk <bunk@stusta.de>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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We added the ability to change a block device's IO elevator scheduler both
at kernel boot and on-the-fly, but we only documented the elevator= boot
parameter. Add a quick how-to on doing it on the fly.
Signed-off-by: Valdis Kletnieks <valdis.kletnieks@vt.edu>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Jens Axboe <axboe@suse.de>
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Add new line of /proc/meminfo output.
Explain the HugePage_ lines in /proc/meminfo (from Bill Irwin).
Change KB to kB since the latter is what is used in the kernel.
Signed-off-by: Randy Dunlap <rdunlap@xenotime.net>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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Improve serial driver documentation:
- Remove CVS id.
- Update pointer to reference driver documentation.
- Add comments about new uart_write_console function.
- Add TIOCM_LOOP modem control bit description.
- Add commentry about enable_ms method being called multiple times.
- Add commentry about startup/shutdown method calling.
- Mention that dereferencing port->info after shutdown is invalid.
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
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* master.kernel.org:/pub/scm/linux/kernel/git/davem/net-2.6: (170 commits)
commit 3d9dd7564d5d7c28eb87b14c13a23806484667f3
Author: Zach Brown <zach.brown@oracle.com>
Date: Fri Apr 14 16:04:18 2006 -0700
[PATCH] ip_output: account for fraggap when checking to add trailer_len
During other work I noticed that ip_append_data() seemed to be forgetting to
include the frag gap in its calculation of a fragment that consumes the rest of
the payload. Herbert confirmed that this was a bug that snuck in during a
previous rework.
Signed-off-by: Zach Brown <zach.brown@oracle.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
commit 08d099974a09faf4cb11ffc46da87073fa132fc0
Author: Linus Walleij <triad@df.lth.se>
Date: Fri Apr 14 16:03:33 2006 -0700
[IRDA]: smsc-ircc2, smcinit support for ALi ISA bridges
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* master.kernel.org:/pub/scm/linux/kernel/git/gregkh/i2c-2.6: (78 commits)
commit e97b81ddbb8b8c72b85330ac4a454a4513dcba8a
Author: Mark M. Hoffman <mhoffman@lightlink.com>
Date: Thu Mar 23 16:50:25 2006 +0100
[PATCH] i2c-parport: Make type parameter mandatory
This patch forces the user to specify what type of adapter is present when
loading i2c-parport or i2c-parport-light. If none is specified, the driver
init simply fails - instead of assuming adapter type 0.
This alleviates the sometimes lengthy boot time delays which can be caused
by accidentally building one of these into a kernel along with several i2c
slave drivers that have lengthy probe routines (e.g. hwmon drivers).
Kconfig and documentation updated accordingly.
Signed-off-by: Mark M. Hoffman <mhoffman@lightlink.com>
Signed-off-by: Jean Delvare <khali@linux-fr.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
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Documentation to describe asynchronous xfrm events to help people
writting HA code in user space.
Signed-off-by: Jamal Hadi Salim <hadi@cyberus.ca>
Signed-off-by: David S. Miller <davem@davemloft.net>
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This updates the DMA API documentation to address a few issues:
- The dma_map_sg() call results are used like pci_map_sg() results:
using sg_dma_address() and sg_dma_len(). That's not wholly obvious
to folk reading _only_ the "new" DMA-API.txt writeup.
- Buffers allocated by dma_alloc_coherent() may not be completely
free of coherency concerns ... some CPUs also have write buffers
that may need to be flushed.
- Cacheline coherence issues are now mentioned as being among issues
which affect dma buffers, and complicate/prevent using of static and
(especially) stack based buffers with the DMA calls.
I don't think many drivers currently need to worry about flushing write
buffers, but I did hit it with one SOC using external SDRAM for DMA
descriptors: without explicit writebuffer flushing, the on-chip DMA
controller accessed descriptors before the CPU completed the writes.
Signed-off-by: David Brownell <dbrownell@users.sourceforge.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
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This patch forces the user to specify what type of adapter is present when
loading i2c-parport or i2c-parport-light. If none is specified, the driver
init simply fails - instead of assuming adapter type 0.
This alleviates the sometimes lengthy boot time delays which can be caused
by accidentally building one of these into a kernel along with several i2c
slave drivers that have lengthy probe routines (e.g. hwmon drivers).
Kconfig and documentation updated accordingly.
Signed-off-by: Mark M. Hoffman <mhoffman@lightlink.com>
Signed-off-by: Jean Delvare <khali@linux-fr.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
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* git://git.kernel.org/pub/scm/linux/kernel/git/sam/kbuild:
kconfig: fix typo in change count initialization
kconfig: recenter menuconfig
kconfig: revert conf behaviour change
kconfig: fix default value for choice input
kbuild: fix NULL dereference in scripts/mod/modpost.c
kbuild: fix mode of checkstack.pl and other files.
kbuild: rebuild initramfs if content of initramfs changes
kbuild: properly pass options to hostcc when doing make O=..
kbuild: modules_install for external modules must not remove existing modules
kbuild: fix make dir/
ver_linux: don't print reiser4progs version if none found
kbuild: mips: fix sed regexp to generate asm-offset.h
kbuild: fix building single targets with make O=.. single-target
kbuild: use relative path to -I
kbuild: fix unneeded rebuilds in drivers/net/chelsio after moving source tree
kbuild: fix unneeded rebuilds in drivers/media/video after moving source tree
kbuild: fix garbled text in modules.txt
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* 'splice' of git://brick.kernel.dk/data/git/linux-2.6-block:
[PATCH] vfs: add splice_write and splice_read to documentation
[PATCH] Remove sys_ prefix of new syscalls from __NR_sys_*
[PATCH] splice: warning fix
[PATCH] another round of fs/pipe.c cleanups
[PATCH] splice: comment styles
[PATCH] splice: add Ingo as addition copyright holder
[PATCH] splice: unlikely() optimizations
[PATCH] splice: speedups and optimizations
[PATCH] pipe.c/fifo.c code cleanups
[PATCH] get rid of the PIPE_*() macros
[PATCH] splice: speedup __generic_file_splice_read
[PATCH] splice: add direct fd <-> fd splicing support
[PATCH] splice: add optional input and output offsets
[PATCH] introduce a "kernel-internal pipe object" abstraction
[PATCH] splice: be smarter about calling do_page_cache_readahead()
[PATCH] splice: optimize the splice buffer mapping
[PATCH] splice: cleanup __generic_file_splice_read()
[PATCH] splice: only call wake_up_interruptible() when we really have to
[PATCH] splice: potential !page dereference
[PATCH] splice: mark the io page as accessed
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With Hansjoerg Lipp <hjlipp@web.de>
Add a README file for the Siemens Gigaset drivers to the Documentation/isdn
directory.
Signed-off-by: Hansjoerg Lipp <hjlipp@web.de>
Signed-off-by: Tilman Schmidt <tilman@imap.cc>
Cc: Karsten Keil <kkeil@suse.de>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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In the memory barrier document, improve the example of the data dependency
barrier situation by:
(1) showing the initial values of the variables involved; and
(2) repeating the instruction sequence description, this time with the data
dependency barrier actually shown to make it clear what the revised
sequence actually is.
Signed-off-by: David Howells <dhowells@redhat.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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Fix the memory barrier documentation to attempt to describe atomic ops
correctly.
atomic_t ops that return a value _do_ imply smp_mb() either side, and so
don't actually require smp_mb__*_atomic_*() special barriers.
Also explains why special barriers exist in addition to normal barriers.
Further fix the memory barrier documents to portray bitwise operation
memory barrier effects correctly following Nick Piggin's comments.
It makes the point that any atomic op that both modifies some state in
memory and returns information on that state implies memory barriers on
both sides.
Signed-off-by: David Howells <dhowells@redhat.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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Fix mtrr-add.c and mtrr-show.c in Doc/mtrr.txt to build cleanly.
Signed-off-by: Randy Dunlap <rdunlap@xenotime.net>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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Fix C source file in Doc/laptop-mode.txt to compile.
Signed-off-by: Randy Dunlap <rdunlap@xenotime.net>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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These are the last conversions of pci_set_dma_mask(),
pci_set_consistent_dma_mask() and pci_dma_supported() to use DMA_xBIT_MASK
constants from linux/dma-mapping.h
Signed-off-by: Tobias Klauser <tklauser@nuerscht.ch>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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Implement the scheduled unexport of panic_timeout.
Signed-off-by: Adrian Bunk <bunk@stusta.de>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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Fix typos, spelling, etc., in Doc/vm/hugetlbpage.txt.
Signed-off-by: Randy Dunlap <rdunlap@xenotime.net>
Cc: David Gibson <david@gibson.dropbear.id.au>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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This patch adds the new splice_write and splice_read file operations to
Documentation/filesystems/vfs.txt.
Signed-off-by: Pekka Enberg <penberg@cs.helsinki.fi>
Signed-off-by: Jens Axboe <axboe@suse.de>
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Overriding the whole EH code is a per-transport, not per-host thing.
Move ->eh_strategy_handler to the transport class, same as
->eh_timed_out.
Downside is that scsi_host_alloc can't check for the total lack of EH
anymore, but the transition period from old EH where we needed it is
long gone already.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Jeff Garzik <jeff@garzik.org>
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From: Keith Mannthey, Andi Kleen
Implement memory hotadd without sparsemem. The memory in the SRAT
hotadd area is just preserved instead and can be activated later.
There are a few restrictions:
- Only one continuous hotadd area allowed per node
The main problem is dealing with the many buggy SRAT tables
that are out there. The strategy here is to reject anything
suspicious.
Originally from Keith Mannthey, with several hacks and changes by AK
and also contributions from Andrew Morton
[ TBD: Problems pointed out by KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>:
1) Goto's rebuild_zonelist patch will not work if CONFIG_MEMORY_HOTPLUG=n.
Rebuilding zonelist is necessary when the system has just memory <
4G at boot, and hot add memory > 4G. because x86_64 has DMA32,
ZONE_NORAML is not included into zonelist at boot time if system
doesn't have memory >4G at boot.
[AK: should just force the higher zones at boot time when SRAT tells us]
2) zone and node's spanned_pages and present_pages are not incremented.
They should be.
For example, our server (ia64/Fujitsu PrimeQuest) can equip memory
from 4G to 1T(maybe 2T in future), and SRAT will *always* say we have
possible 1T +memory. (Microsoft requires "write all possible memory
in SRAT") When we reserve memmap for possible 1T memory, Linux will
not work well in +minimum 4G configuraion ;)
[AK: needs limiting to 5-10% of max memory]
]
Signed-off-by: Andi Kleen <ak@suse.de>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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Signed-off-by: Brian Gerst <bgerst@didntduck.org>
Signed-off-by: Sam Ravnborg <sam@ravnborg.org>
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Update LART site URL.
The LART website moved to http://www.lartmaker.nl/. This patch
updates the URL in CpuFreq specific files.
Signed-off-by: Erik Mouw <erik@bitwizard.nl>
Signed-off-by: Dave Jones <davej@redhat.com>
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* master.kernel.org:/pub/scm/linux/kernel/git/perex/alsa: (28 commits)
[ALSA] Kconfig SND_SEQUENCER_OSS help text fix
[ALSA] Add Aux input switch control for Aureon Universe
[ALSA] pcxhr - Fix the crash with REV01 board
[ALSA] sound/pci/hda: use create_singlethread_workqueue()
[ALSA] hda-intel - Add support of ATI SB600
[ALSA] cs4281 - Fix the check of timeout in probe
[ALSA] cs4281 - Fix the check of right channel
[ALSA] Test volume resolution of usb audio at initialization
[ALSA] maestro3.c: fix BUG, optimization
[ALSA] HDA/Realtek: multiple input mux definitions and pin mode additions
[ALSA] AdLib FM card driver
[ALSA] Fix / clean up PCM-OSS setup hooks
[ALSA] Clean up PCM codes (take 2)
[ALSA] Tiny clean up of PCM codes
[ALSA] ISA drivers bailing on first !enable[i]
[ALSA] Remove obsolete kfree_nocheck call
[ALSA] Remove obsolete kfree_nocheck call
[ALSA] Add snd-als300 driver for Avance Logic ALS300/ALS300+ soundcards
[ALSA] Add snd-riptide driver for Conexant Riptide chip
[ALSA] hda-codec - Fix noisy output wtih AD1986A 3stack model
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* git://git.kernel.org/pub/scm/linux/kernel/git/bunk/trivial: (48 commits)
Documentation: fix minor kernel-doc warnings
BUG_ON() Conversion in drivers/net/
BUG_ON() Conversion in drivers/s390/net/lcs.c
BUG_ON() Conversion in mm/slab.c
BUG_ON() Conversion in mm/highmem.c
BUG_ON() Conversion in kernel/signal.c
BUG_ON() Conversion in kernel/signal.c
BUG_ON() Conversion in kernel/ptrace.c
BUG_ON() Conversion in ipc/shm.c
BUG_ON() Conversion in fs/freevxfs/
BUG_ON() Conversion in fs/udf/
BUG_ON() Conversion in fs/sysv/
BUG_ON() Conversion in fs/inode.c
BUG_ON() Conversion in fs/fcntl.c
BUG_ON() Conversion in fs/dquot.c
BUG_ON() Conversion in md/raid10.c
BUG_ON() Conversion in md/raid6main.c
BUG_ON() Conversion in md/raid5.c
Fix minor documentation typo
BFP->BPF in Documentation/networking/tuntap.txt
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* master.kernel.org:/pub/scm/linux/kernel/git/mchehab/v4l-dvb: (49 commits)
V4L/DVB (3667b): cpia2: fix function prototype
V4L/DVB (3702): Make msp3400 routing defines more consistent
V4L/DVB (3700): Remove obsolete commands from tvp5150.c
V4L/DVB (3697): More msp3400 and bttv fixes
V4L/DVB (3696): Previous change for cx2341X boards broke the remote support
V4L/DVB (3693): Fix msp3400c and bttv stereo/mono/bilingual detection/handling
V4L/DVB (3692): Keep experimental SLICED_VBI defines under an #if 0
V4L/DVB (3689): Kconfig: fix VP-3054 Secondary I2C Bus build configuration menu dependencies
V4L/DVB (3673): Fix budget-av CAM reset
V4L/DVB (3672): Fix memory leak in dvr open
V4L/DVB (3671): New module parameter 'tv_standard' (dvb-ttpci driver)
V4L/DVB (3670): Fix typo in comment
V4L/DVB (3669): Configurable dma buffer size for saa7146-based budget dvb cards
V4L/DVB (3653h): Move usb v4l docs into Documentation/video4linux
V4L/DVB (3667a): Fix SAP + stereo mode at msp3400
V4L/DVB (3666): Remove trailing newlines
V4L/DVB (3665): Add new NEC uPD64031A and uPD64083 i2c drivers
V4L/DVB (3663): Fix msp3400c wait time and better audio mode fallbacks
V4L/DVB (3662): Don't set msp3400c-non-existent register
V4L/DVB (3661): Add wm8739 stereo audio ADC i2c driver
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* master.kernel.org:/pub/scm/linux/kernel/git/brodo/pcmcia-2.6: (33 commits)
[PATCH] pcmcia: declare pccard_iodyn_ops (fix m8xx_pcmcia.c compilation error)
[PATCH] pcmcia: fix pcmcia_device_remove oops
[PATCH] pcmcia: Add support for Possio GCC AKA PCMCIA Siemens MC45
[PATCH] pcmcia: pseudo device handling update
[PATCH] pcmcia: convert DEV_OK to pcmcia_dev_present
[PATCH] pcmcia: use bitfield instead of p_state and state
[PATCH] pcmcia: remove unused p_dev->state flags
[PATCH] pcmcia: make pcmcia_release_{io,irq} static
[PATCH] pcmcia: add return value to _config() functions
[PATCH] pcmcia: remove dev_link_t and client_handle_t indirection
[PATCH] pcmcia: embed dev_link_t into struct pcmcia_device
[PATCH] pcmcia: rename pcmcia_device.state
[PATCH] pcmcia: remove unneeded Vcc pseudo setting
[PATCH] pcmcia: remove export of pcmcia_release_configuration
[PATCH] pcmcia: default suspend and resume handling
[PATCH] pcmcia: convert remaining users of pcmcia_release_io and _irq
[PATCH] pcmcia: add pcmcia_disable_device
[PATCH] serial_cs: add Merlin U630 IDs
[PATCH] pcmcia: AT91RM9200 Compact Flash driver
[PATCH] pcmcia: socket.functions starts with 1
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This patch updates the comments to match the actual code.
Signed-off-by: Martin Waitz <tali@admingilde.org>
Signed-off-by: Adrian Bunk <bunk@stusta.de>
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- Move documentation for usb v4l devices from
Documentation/usb to Documentation/video4linux.
- Removed trailing whitespace.
- Update Kconfig help text links to reflect the new file locations.
Signed-off-by: Michael Krufky <mkrufky@linuxtv.org>
Signed-off-by: Mauro Carvalho Chehab <mchehab@infradead.org>
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There seem to be many variants of this cards with different
feature sets. This entry supports
analog TV, CVBS and s-video input, FM radio and DVB-T
if they are supported by the hardware.
Signed-off-by: Hartmut Hackmann <hartmut.hackmann@t-online.de>
Signed-off-by: Mauro Carvalho Chehab <mchehab@infradead.org>
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Added ID entries for the Genius VideoWonder DVB-T
and the LifeView FlyTV Platinum Gold
Signed-off-by: Hartmut Hackmann <hartmut.hackmann@t-online.de>
Signed-off-by: Mauro Carvalho Chehab <mchehab@infradead.org>
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SNES gamepads and mice share the same type of interface so they both can be
connected to the parallel port using a simple interface. Adding mouse
support to a gamepad driver may sound funny at first, but doing so in this
case makes it possible to connect and SNES gamepads and mice at the same
time, on the same port.
Signed-off-by: Raphael Assenat <raph@raphnet.net>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Dmitry Torokhov <dtor@mail.ru>
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This patch fixes a minor typo in Documentation/acpi-hotkey.txt.
Signed-off-by: Adrian Bunk <bunk@stusta.de>
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BFP should be BPF (BSD Packet Filter)
Signed-off-by: Cal Peake <cp@absolutedigital.net>
Signed-off-by: Adrian Bunk <bunk@stusta.de>
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The previous patch somewhat diverted the train of thought.
Here I am trying to bring the valued reader back on track.
Signed-off-by: Stefan Richter <stefanr@s5r6.in-berlin.de>
Signed-off-by: Adrian Bunk <bunk@stusta.de>
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Doc/kernel-parameters.txt: mention modinfo and sysfs
Signed-off-by: Stefan Richter <stefanr@s5r6.in-berlin.de>
Signed-off-by: Adrian Bunk <bunk@stusta.de>
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Doc/kernel-parameters.txt: delete false version information and history
Signed-off-by: Stefan Richter <stefanr@s5r6.in-berlin.de>
Signed-off-by: Adrian Bunk <bunk@stusta.de>
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Documentation: Make kernel-ABI.txt 80 columns wide
Note that this only has line-wrapping and white-space changes.
No text was changed at all.
Signed-Off-By: Horms <horms@verge.net.au>
Signed-off-by: Adrian Bunk <bunk@stusta.de>
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My patch to add brief documentation of the nomca boot parameter
added it out of alphabetical order.
Signed-Off-By: Horms <horms@verge.net.au>
Signed-off-by: Adrian Bunk <bunk@stusta.de>
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Signed-off-by: Uwe Zeisberger <zeisberg@informatik.uni-freiburg.de>
Signed-off-by: Adrian Bunk <bunk@stusta.de>
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s/ducument/document/
Signed-off-by: Adrian Bunk <bunk@stusta.de>
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The attached patch documents the Linux kernel's memory barriers.
I've updated it from the comments I've been given.
The per-arch notes sections are gone because it's clear that there are so many
exceptions, that it's not worth having them.
I've added a list of references to other documents.
I've tried to get rid of the concept of memory accesses appearing on the bus;
what matters is apparent behaviour with respect to other observers in the
system.
Interrupts barrier effects are now considered to be non-existent. They may be
there, but you may not rely on them.
I've added a couple of definition sections at the top of the document: one to
specify the minimum execution model that may be assumed, the other to specify
what this document refers to by the term "memory".
I've made greater mention of the use of mmiowb().
I've adjusted the way in which caches are described, and described the fun
that can be had with cache coherence maintenance being unordered and data
dependency not being necessarily implicit.
I've described (smp_)read_barrier_depends().
I've rearranged the order of the sections, so that memory barriers are
discussed in abstract first, and then described the memory barrier facilities
available on Linux, before going on to more real-world discussions and examples.
I've added information about the lack of memory barriering effects with atomic
ops and bitops.
I've added information about control dependencies.
I've added more diagrams to illustrate caching interactions between CPUs.
Signed-off-by: David Howells <dhowells@redhat.com>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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As announced, lookup_hash() can now become static.
Signed-off-by: Adrian Bunk <bunk@stusta.de>
Cc: Christoph Hellwig <hch@lst.de>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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The LED class/subsystem takes John Lenz's work and extends and alters it to
give what I think should be a fairly universal LED implementation.
The series consists of several logical units:
* LED Core + Class implementation
* LED Trigger Core implementation
* LED timer trigger (example of a complex trigger)
* LED device drivers for corgi, spitz and tosa Zaurus models
* LED device driver for locomo LEDs
* LED device driver for ARM ixp4xx LEDs
* Zaurus charging LED trigger
* IDE disk activity LED trigger
* NAND MTD activity LED trigger
Why?
====
LEDs are really simple devices usually amounting to a GPIO that can be turned
on and off so why do we need all this code? On handheld or embedded devices
they're an important part of an often limited user interface. Both users and
developers want to be able to control and configure what the LED does and the
number of different things they'd potentially want the LED to show is large.
A subsystem is needed to try and provide all this different functionality in
an architecture independent, simple but complete, generic and scalable manner.
The alternative is for everyone to implement just what they need hidden away
in different corners of the kernel source tree and to provide an inconsistent
interface to userspace.
Other Implementations
=====================
I'm aware of the existing arm led implementation. Currently the new subsystem
and the arm code can coexist quite happily. Its up to the arm community to
decide whether this new interface is acceptable to them. As far as I can see,
the new interface can do everything the existing arm implementation can with
the advantage that the new code is architecture independent and much more
generic, configurable and scalable.
I'm prepared to make the conversion to the LED subsystem (or assist with it)
if appropriate.
Implementation Details
======================
I've stripped a lot of code out of John's original LED class. Colours were
removed as LED colour is now part of the device name. Multiple colours are to
be handled as multiple led devices. This means you get full control over each
colour. I also removed the LED hardware timer code as the generic timer isn't
going to add much overhead and is just as useful. I also decided to have the
LED core track the current LED status (to ease suspend/resume handling)
removing the need for brightness_get implementations in the LED drivers.
An underlying design philosophy is simplicity. The aim is to keep a small
amount of code giving as much functionality as possible.
The major new idea is the led "trigger". A trigger is a source of led events.
Triggers can either be simple or complex. A simple trigger isn't
configurable and is designed to slot into existing subsystems with minimal
additional code. Examples are the ide-disk, nand-disk and zaurus-charging
triggers. With leds disabled, the code optimises away. Examples are
nand-disk and ide-disk.
Complex triggers whilst available to all LEDs have LED specific parameters and
work on a per LED basis. The timer trigger is an example.
You can change triggers in a similar manner to the way an IO scheduler is
chosen (via /sys/class/leds/somedevice/trigger).
So far there are only a handful of examples but it should easy to add further
LED triggers without too much interference into other subsystems.
Known Issues
============
The LED Trigger core cannot be a module as the simple trigger functions would
cause nightmare dependency issues. I see this as a minor issue compared to
the benefits the simple trigger functionality brings. The rest of the LED
subsystem can be modular.
Some leds can be programmed to flash in hardware. As this isn't a generic LED
device property, I think this should be exported as a device specific sysfs
attribute rather than part of the class if this functionality is required (eg.
to keep the led flashing whilst the device is suspended).
Future Development
==================
At the moment, a trigger can't be created specifically for a single LED.
There are a number of cases where a trigger might only be mappable to a
particular LED. The addition of triggers provided by the LED driver should
cover this option and be possible to add without breaking the current
interface.
A CPU activity trigger similar to that found in the arm led implementation
should be trivial to add.
This patch:
Add some brief documentation of the design decisions behind the LED class and
how it appears to users.
Signed-off-by: Richard Purdie <rpurdie@rpsys.net>
Cc: Russell King <rmk@arm.linux.org.uk>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
|
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find_trylock_page() is an odd interface in that it doesn't take a reference
like the others. Now that XFS no longer uses it, and its last remaining
caller actually wants an elevated refcount, opencode that callsite and
schedule find_trylock_page() for removal.
Signed-off-by: Nick Piggin <npiggin@suse.de>
Acked-by: Hugh Dickins <hugh@veritas.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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