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Clk_prepare_enable and clk_disable_unprepare combine clk_prepare and
clk_enable, and clk_disable and clk_unprepare. They make the code more
concise, and ensure that clk_unprepare is called when clk_enable fails.
A simplified version of the semantic patch that introduces calls to these
functions is as follows: (http://coccinelle.lip6.fr/)
// <smpl>
@@
expression e;
@@
- clk_prepare(e);
- clk_enable(e);
+ clk_prepare_enable(e);
@@
expression e;
@@
- clk_disable(e);
- clk_unprepare(e);
+ clk_disable_unprepare(e);
// </smpl>
Signed-off-by: Julia Lawall <Julia.Lawall@lip6.fr>
Acked-by: Viresh Kumar <viresh.kumar@linaro.org>
Signed-off-by: Wim Van Sebroeck <wim@iguana.be>
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This makes the code a bit smaller by getting rid of
some boilerplate code.
Signed-off-by: Gabor Juhos <juhosg@openwrt.org>
Signed-off-by: Wim Van Sebroeck <wim@iguana.be>
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Pull Xtensa patchset from Chris Zankel:
"This contains support of device trees, many fixes, and code clean-ups"
* tag 'xtensa-20121218' of git://github.com/czankel/xtensa-linux: (33 commits)
xtensa: don't try to build DTB when OF is disabled
xtensa: set the correct ethernet address for xtfpga
xtensa: clean up files to make them code-style compliant
xtensa: provide endianness macro for sparse
xtensa: fix RASID SR initialization
xtensa: initialize CPENABLE SR when core has one
xtensa: reset all timers on initialization
Use for_each_compatible_node() macro.
xtensa: add XTFPGA DTS
xtensa: add support for the XTFPGA boards
xtensa: add device trees support
xtensa: add IRQ domains support
xtensa: add U-Boot image support (uImage).
xtensa: clean up boot make rules
xtensa: fix mb and wmb definitions
xtensa: add s32c1i-based spinlock implementations
xtensa: add s32c1i-based bitops implementations
xtensa: add s32c1i-based atomic ops implementations
xtensa: add s32c1i sanity check
xtensa: add trap_set_handler function
...
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git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull one final 386 removal patch from Peter Anvin.
IRQ 13 FPU error handling is gone. That was not one of the proudest
moments in PC history.
* 'x86/nuke386' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
x86, 386 removal: Remove support for IRQ 13 FPU error reporting
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git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull small x86 fixes from Peter Anvin:
"A collection of very small fixes, mostly pure documentation."
* 'x86-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
x86, doc: Document that bootloader ID 4 is used also by iPXE
x86, doc: Add a formal bootloader ID for kexec-tools
x86, 8042: Enable A20 using KBC to fix S3 resume on some MSI laptops
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Pull MTD updates from David Woodhouse:
- Various cleanups especially in NAND tests
- Add support for NAND flash on BCMA bus
- DT support for sh_flctl and denali NAND drivers
- Kill obsolete/superceded drivers (fortunet, nomadik_nand)
- Fix JFFS2 locking bug in ENOMEM failure path
- New SPI flash chips, as usual
- Support writing in 'reliable mode' for DiskOnChip G4
- Debugfs support in nandsim
* tag 'for-linus-20121219' of git://git.infradead.org/linux-mtd: (96 commits)
mtd: nand: typo in nand_id_has_period() comments
mtd: nand/gpio: use io{read,write}*_rep accessors
mtd: block2mtd: throttle writes by calling balance_dirty_pages_ratelimited.
mtd: nand: gpmi: reset BCH earlier, too, to avoid NAND startup problems
mtd: nand/docg4: fix and improve read of factory bbt
mtd: nand/docg4: reserve bb marker area in ecclayout
mtd: nand/docg4: add support for writing in reliable mode
mtd: mxc_nand: reorder part_probes to let cmdline override other sources
mtd: mxc_nand: fix unbalanced clk_disable() in error path
mtd: nandsim: Introduce debugfs infrastructure
mtd: physmap_of: error checking to prevent a NULL pointer dereference
mtg: docg3: potential divide by zero in doc_write_oob()
mtd: bcm47xxnflash: writing support
mtd: tests/read: initialize buffer for whole next page
mtd: at91: atmel_nand: return bit flips for the PMECC read_page()
mtd: fix recovery after failed write-buffer operation in cfi_cmdset_0002.c
mtd: nand: onfi need to be probed in 8 bits mode
mtd: nand: add NAND_BUSWIDTH_AUTO to autodetect bus width
mtd: nand: print flash size during detection
mted: nand_wait_ready timeout fix
...
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Commit 8d4516904b39 ("watchdog: Fix CPU hotplug regression") causes an
oops or hard lockup when doing
echo 0 > /proc/sys/kernel/nmi_watchdog
echo 1 > /proc/sys/kernel/nmi_watchdog
and the kernel is booted with nmi_watchdog=1 (default)
Running laptop-mode-tools and disconnecting/connecting AC power will
cause this to trigger, making it a common failure scenario on laptops.
Instead of bailing out of watchdog_disable() when !watchdog_enabled we
can initialize the hrtimer regardless of watchdog_enabled status. This
makes it safe to call watchdog_disable() in the nmi_watchdog=0 case,
without the negative effect on the enabled => disabled => enabled case.
All these tests pass with this patch:
- nmi_watchdog=1
echo 0 > /proc/sys/kernel/nmi_watchdog
echo 1 > /proc/sys/kernel/nmi_watchdog
- nmi_watchdog=0
echo 0 > /sys/devices/system/cpu/cpu1/online
- nmi_watchdog=0
echo mem > /sys/power/state
Bugzilla: https://bugzilla.kernel.org/show_bug.cgi?id=51661
Cc: <stable@vger.kernel.org> # v3.7
Cc: Norbert Warmuth <nwarmuth@t-online.de>
Cc: Joseph Salisbury <joseph.salisbury@canonical.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Bjørn Mork <bjorn@mork.no>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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Pull pwm changes from Thierry Reding:
"A new driver has been added for the SPEAr platform and the
TWL4030/6030 driver has been replaced by two drivers that control the
regular PWMs and the PWM driven LEDs provided by the chips.
The vt8500, tiecap, tiehrpwm, i.MX, LPC32xx and Samsung drivers have
all been improved and the device tree bindings now support the PWM
signal polarity."
Fix up trivial conflicts due to __devinit/exit removal.
* tag 'for-3.8-rc1' of git://gitorious.org/linux-pwm/linux-pwm: (21 commits)
pwm: samsung: add missing s3c->pwm_id assignment
pwm: lpc32xx: Set the chip base for dynamic allocation
pwm: lpc32xx: Properly disable the clock on device removal
pwm: lpc32xx: Fix the PWM polarity
pwm: i.MX: eliminate build warning
pwm: Export of_pwm_xlate_with_flags()
pwm: Remove pwm-twl6030 driver
pwm: New driver to support PWM driven LEDs on TWL4030/6030 series of PMICs
pwm: New driver to support PWMs on TWL4030/6030 series of PMICs
pwm: pwm-tiehrpwm: pinctrl support
pwm: tiehrpwm: Add device-tree binding
pwm: pwm-tiehrpwm: Adding TBCLK gating support.
pwm: pwm-tiecap: pinctrl support
pwm: tiecap: Add device-tree binding
pwm: Add TI PWM subsystem driver
pwm: Device tree support for PWM polarity
pwm: vt8500: Ensure PWM clock is enabled during pwm_config
pwm: vt8500: Fix build error
pwm: spear: Staticize spear_pwm_config()
pwm: Add SPEAr PWM chip driver support
...
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Pull battery update, part 2, from Anton Vorontsov:
"These are left overs that I didn't have time to review/apply before
the merge window opened. I didn't want to "spoil" the first pull
request with these late patches, so they were not included:
- A small patch for the RX51 OMAP board (Nokia N900 phone), the patch
creates a battery monitor device instance, so that it can be
probed. It was acked by the OMAP maintainer;
- A couple of late bug fixes for the charger-manager: corrects corner
cases for the battery full handling."
* tag 'for-v3.8-part2' of git://git.infradead.org/battery-2.6:
charger-manager: Fix bug when check dropped voltage after fullbatt event
charger-manager: Fix bug related to checking fully charged state of battery
ARM: OMAP: rx51: Register platform device for rx51_battery
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git://git.kernel.org/pub/scm/linux/kernel/git/rusty/linux
Pull module update from Rusty Russell:
"Nothing all that exciting; a new module-from-fd syscall for those who
want to verify the source of the module (ChromeOS) and/or use standard
IMA on it or other security hooks."
* tag 'modules-next-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/rusty/linux:
MODSIGN: Fix kbuild output when using default extra_certificates
MODSIGN: Avoid using .incbin in C source
modules: don't hand 0 to vmalloc.
module: Remove a extra null character at the top of module->strtab.
ASN.1: Use the ASN1_LONG_TAG and ASN1_INDEFINITE_LENGTH constants
ASN.1: Define indefinite length marker constant
moduleparam: use __UNIQUE_ID()
__UNIQUE_ID()
MODSIGN: Add modules_sign make target
powerpc: add finit_module syscall.
ima: support new kernel module syscall
add finit_module syscall to asm-generic
ARM: add finit_module syscall to ARM
security: introduce kernel_module_from_file hook
module: add flags arg to sys_finit_module()
module: add syscall to load module from fd
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git://git.infradead.org/users/dwmw2/byteswap
Pull preparatory gcc intrisics bswap patch from David Woodhouse:
"This single patch is effectively a no-op for now. It enables
architectures to opt in to using GCC's __builtin_bswapXX() intrinsics
for byteswapping, and if we merge this now then the architecture
maintainers can enable it for their arch during the next cycle without
dependency issues.
It's worth making it a par-arch opt-in, because although in *theory*
the compiler should never do worse than hand-coded assembler (and of
course it also ought to do a lot better on platforms like Atom and
PowerPC which have load-and-swap or store-and-swap instructions), that
isn't always the case. See
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=46453
for example."
* tag 'byteswap-for-linus-20121219' of git://git.infradead.org/users/dwmw2/byteswap:
byteorder: allow arch to opt to use GCC intrinsics for byteswapping
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Commit 8dd2cb7e880d ("block: discard granularity might not be power of
2") changed a couple of 'binary and' operations into modulus operations.
Which turned the harmless case of a zero discard_granularity into a
possible divide-by-zero.
The code also had a much more subtle bug: it was doing the modulus of a
value in bytes using 'sector_t'. That was always conceptually wrong,
but didn't actually matter back when the code assumed a power-of-two
granularity: we only looked at the low bits anyway.
But with potentially arbitrary sector numbers, using a 'sector_t' to
express bytes is very very wrong: depending on configuration it limits
the starting offset of the device to just 32 bits, and any overflow
would result in a wrong value if the modulus wasn't a power-of-two.
So re-write the code to not only protect against the divide-by-zero, but
to do the starting sector arithmetic in sectors, and using the proper
types.
[ For any mathematicians out there: it also looks monumentally stupid to
do the 'modulo granularity' operation *twice*, never mind having a "+
granularity" in the second modulus op.
But that's the easiest way to avoid negative values or overflow, and
it is how the original code was done. ]
Reported-by: Ingo Molnar <mingo@kernel.org>
Reported-by: Doug Anderson <dianders@chromium.org>
Cc: Neil Brown <neilb@suse.de>
Cc: Shaohua Li <shli@fusionio.com>
Acked-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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Signed-off-by: Max Filippov <jcmvbkbc@gmail.com>
Signed-off-by: Chris Zankel <chris@zankel.net>
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The last byte of the mac address is determined by a DIP switch, so
update the OF property with that address.
Signed-off-by: Chris Zankel <chris@zankel.net>
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Remove heading and trailing spaces, trim trailing lines, and wrap lines
that are longer than 80 characters.
Signed-off-by: Chris Zankel <chris@zankel.net>
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Signed-off-by: Max Filippov <jcmvbkbc@gmail.com>
Signed-off-by: Chris Zankel <chris@zankel.net>
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set_rasid_register accepts new RASID SR value, but ASID_USER_FIRST is
ASID value for the ring 1; RASID value is made by ASID_INSERT macro.
Signed-off-by: Max Filippov <jcmvbkbc@gmail.com>
Signed-off-by: Chris Zankel <chris@zankel.net>
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XCHAL_CP_NUM is defined in variant/tie.h and it is not included by
head.S, leaving CPENABLE register uninitialised. XCHAL_HAVE_CP is
defined in variant/core.h to 1 when core has CPENABLE SR.
Signed-off-by: Max Filippov <jcmvbkbc@gmail.com>
Signed-off-by: Chris Zankel <chris@zankel.net>
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There are XCHAL_NUM_TIMERS, reset them all.
Signed-off-by: Max Filippov <jcmvbkbc@gmail.com>
Signed-off-by: Chris Zankel <chris@zankel.net>
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Signed-off-by: Wei Yongjun <yongjun_wei@trendmicro.com.cn>
Acked-by: Max Filippov <jcmvbkbc@gmail.com>
Signed-off-by: Chris Zankel <chris@zankel.net>
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Add common XTFPGA parts as *.dtsi (base board, flash) and DTS for LX60
and for ML605.
Signed-off-by: Max Filippov <jcmvbkbc@gmail.com>
Signed-off-by: Chris Zankel <chris@zankel.net>
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The Avnet LX60/LX110/LX200 board is an FPGA board that can be configured with
an Xtensa processor and an OpenCores Ethernet device.
Signed-off-by: Chris Zankel <chris@zankel.net>
Signed-off-by: Max Filippov <jcmvbkbc@gmail.com>
Signed-off-by: Chris Zankel <chris@zankel.net>
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Device trees allow specification of hardware topology and device
parameters at runtime instead of hard-coding them in platform setup
code. This allows running single binary kernel on a range of compatible
boards.
New boot parameters tag BP_TAG_FDT is allocated and a pointer to flat
device tree is passed in it.
Note that current interrupt mapping scheme uses single cell for
interrupt identification. That means that IRQ numbers used in DTS must
be CPU internal IRQ numbers, not external. It is possible to extend
interrupt identification to two cells, and use second cell to tell
external IRQ numbers form internal. That would allow to use single DTS
on multiple boards with different mapping of external IRQ numbers.
Signed-off-by: Max Filippov <jcmvbkbc@gmail.com>
Signed-off-by: Chris Zankel <chris@zankel.net>
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IRQ domains provide a mechanism for conversion of linux IRQ numbers to
hardware IRQ numbers and vice versus. It is used by OpenFirmware for
linking device tree objects to their respective interrupt controllers.
Signed-off-by: Max Filippov <jcmvbkbc@gmail.com>
Signed-off-by: Chris Zankel <chris@zankel.net>
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Signed-off-by: Max Filippov <jcmvbkbc@gmail.com>
Signed-off-by: Chris Zankel <chris@zankel.net>
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- remove duplicate rules for binary and packed image
- use predefined macros for ld/objcopy/gzip
- remove build-id section from bootable elf image
Signed-off-by: Max Filippov <jcmvbkbc@gmail.com>
Signed-off-by: Chris Zankel <chris@zankel.net>
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Define mb and wmb as memw to force memory barrier.
Signed-off-by: Max Filippov <jcmvbkbc@gmail.com>
Signed-off-by: Chris Zankel <chris@zankel.net>
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Signed-off-by: Max Filippov <jcmvbkbc@gmail.com>
Signed-off-by: Chris Zankel <chris@zankel.net>
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Signed-off-by: Max Filippov <jcmvbkbc@gmail.com>
Signed-off-by: Chris Zankel <chris@zankel.net>
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Signed-off-by: Max Filippov <jcmvbkbc@gmail.com>
Signed-off-by: Chris Zankel <chris@zankel.net>
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Add a brief sanity test of S32C1I functionality. This instruction
is needed by the kernel and userland as part of the base ABI
(including GCC atomic builtins, certain threading packages, future
atomic support in the C++ standard, etc). However, correct operation
of this instruction requires some cooperation by hardware external to
the processor (such as bus bridge, bus fabric, or memory controller).
Minimally exercising this mechanism and reporting explicit status
early in the boot process is helpful to chip vendors using the Linux
kernel as a benchmark of correctness of hardware.
As it turns out, S32C1I is not exercised by the kernel and by uClibc
based userland as of early June 2008. This is expected to change
soon as both incorporate more recent open source developments.
Signed-off-by: Marc Gauthier <marc@tensilica.com>
Signed-off-by: Max Filippov <jcmvbkbc@gmail.com>
Signed-off-by: Chris Zankel <chris@zankel.net>
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trap_set_handler sets new C-handler in the exception table and returns
previous handler.
Signed-off-by: Max Filippov <jcmvbkbc@gmail.com>
Signed-off-by: Chris Zankel <chris@zankel.net>
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In order to use S32C1I instruction on cores with ATOMCTL SR the register
must be properly initialized.
Signed-off-by: Max Filippov <jcmvbkbc@gmail.com>
Signed-off-by: Chris Zankel <chris@zankel.net>
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Although scompare1 may be saved/restored by xchal_ncp_{load,store}
macros, explicit save/restore of registers manipulated by the kernel
itself is considered more correct.
Signed-off-by: Max Filippov <jcmvbkbc@gmail.com>
Signed-off-by: Chris Zankel <chris@zankel.net>
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Signed-off-by: Max Filippov <jcmvbkbc@gmail.com>
Signed-off-by: Chris Zankel <chris@zankel.net>
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Signed-off-by: Max Filippov <jcmvbkbc@gmail.com>
Signed-off-by: Chris Zankel <chris@zankel.net>
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Signed-off-by: Max Filippov <jcmvbkbc@gmail.com>
Signed-off-by: Chris Zankel <chris@zankel.net>
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Signed-off-by: Max Filippov <jcmvbkbc@gmail.com>
Signed-off-by: Chris Zankel <chris@zankel.net>
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This fixes the following allmodconfig build error:
drivers/uio/uio_dmem_genirq.c:95:18: error: 'DMA_ERROR_CODE' undeclared (first use in this function)
drivers/uio/uio_dmem_genirq.c:238:18: error: 'DMA_ERROR_CODE' undeclared (first use in this function)
make[3]: *** [drivers/uio/uio_dmem_genirq.o] Error 1
Signed-off-by: Max Filippov <jcmvbkbc@gmail.com>
Signed-off-by: Chris Zankel <chris@zankel.net>
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This fixes the following build error in allyesconfig:
drivers/tty/serial/8250/8250_early.c: In function 'parse_options':
drivers/tty/serial/8250/8250_early.c:160:18: error: 'BASE_BAUD' undeclared (first use in this function)
Reported-by: Fengguang Wu <fengguang.wu@intel.com>
Signed-off-by: Max Filippov <jcmvbkbc@gmail.com>
Signed-off-by: Chris Zankel <chris@zankel.net>
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Use ENDPROC() to mark the end of assembler functions.
Signed-off-by: Chris Zankel <chris@zankel.net>
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Manually load references to exc_table from the explicit literal in order
to fit DoubleExceptionVector.literals into the available 16-byte gap
before DoubleExceptionVector.text in the absence of link time
relaxation. Without this fix DoubleExceptionVector.literal section
overlaps DoubleExceptionVector.text section in the linked vmlinux image.
Signed-off-by: Max Filippov <jcmvbkbc@gmail.com>
Signed-off-by: Chris Zankel <chris@zankel.net>
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The default linker behavior is to optimize identical literal values and
remove unnecessary overhead from assembler-generated "longcall" sequences
to reduce code size. Provide an option to disable this behavior to improve
compile time.
Signed-off-by: Chris Zankel <chris@zankel.net>
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Signed-off-by: Nicolas Kaiser <nikai@nikai.net>
Signed-off-by: Chris Zankel <chris@zankel.net>
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Fix the definition of the function ccount_read to be compatible
to the member read of the structure clocksource.
Signed-off-by: Wanlong Gao <wanlong.gao@gmail.com>
Signed-off-by: Chris Zankel <chris@zankel.net>
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Pull i2c-embedded changes from Wolfram Sang:
- CBUS driver (an I2C variant)
- continued rework of the omap driver
- s3c2410 gets lots of fixes and gains pinctrl support
- at91 gains DMA support
- the GPIO muxer gains devicetree probing
- typical fixes and additions all over
* 'i2c-embedded/for-next' of git://git.pengutronix.de/git/wsa/linux: (45 commits)
i2c: omap: Remove the OMAP_I2C_FLAG_RESET_REGS_POSTIDLE flag
i2c: at91: add dma support
i2c: at91: change struct members indentation
i2c: at91: fix compilation warning
i2c: mxs: Do not disable the I2C SMBus quick mode
i2c: mxs: Handle i2c DMA failure properly
i2c: s3c2410: Remove recently introduced performance overheads
i2c: ocores: Move grlib set/get functions into #ifdef CONFIG_OF block
i2c: s3c2410: Add fix for i2c suspend/resume
i2c: s3c2410: Fix code to free gpios
i2c: i2c-cbus-gpio: introduce driver
i2c: ocores: Add support for the GRLIB port of the controller and use function pointers for getreg and setreg functions
i2c: ocores: Add irq support for sparc
i2c: omap: Move the remove constraint
ARM: dts: cfa10049: Add the i2c muxer buses to the CFA-10049
i2c: s3c2410: do not special case HDMIPHY stuck bus detection
i2c: s3c2410: use exponential back off while polling for bus idle
i2c: s3c2410: do not generate STOP for QUIRK_HDMIPHY
i2c: s3c2410: grab adapter lock while changing i2c clock
i2c: s3c2410: Add support for pinctrl
...
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Merge patches from Andrew Morton:
"Most of the rest of MM, plus a few dribs and drabs.
I still have quite a few irritating patches left around: ones with
dubious testing results, lack of review, ones which should have gone
via maintainer trees but the maintainers are slack, etc.
I need to be more activist in getting these things wrapped up outside
the merge window, but they're such a PITA."
* emailed patches from Andrew Morton <akpm@linux-foundation.org>: (48 commits)
mm/vmscan.c: avoid possible deadlock caused by too_many_isolated()
vmscan: comment too_many_isolated()
mm/kmemleak.c: remove obsolete simple_strtoul
mm/memory_hotplug.c: improve comments
mm/hugetlb: create hugetlb cgroup file in hugetlb_init
mm/mprotect.c: coding-style cleanups
Documentation: ABI: /sys/devices/system/node/
slub: drop mutex before deleting sysfs entry
memcg: add comments clarifying aspects of cache attribute propagation
kmem: add slab-specific documentation about the kmem controller
slub: slub-specific propagation changes
slab: propagate tunable values
memcg: aggregate memcg cache values in slabinfo
memcg/sl[au]b: shrink dead caches
memcg/sl[au]b: track all the memcg children of a kmem_cache
memcg: destroy memcg caches
sl[au]b: allocate objects from memcg cache
sl[au]b: always get the cache from its page in kmem_cache_free()
memcg: skip memcg kmem allocations in specified code regions
memcg: infrastructure to match an allocation to the right cache
...
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git://git.kernel.org/pub/scm/linux/kernel/git/groeck/linux-staging
Pull hwmon fixlet from Guenter Roeck:
"Fix fallout from __devexit removal"
* tag 'hwmon-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/groeck/linux-staging:
hwmon: (twl4030-madc-hwmon) Fix warning message caused by removal of __devexit
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Pull tile updates from Chris Metcalf:
"These are a smattering of minor changes from Tilera and other folks,
mostly in the ptrace area."
* git://git.kernel.org/pub/scm/linux/kernel/git/cmetcalf/linux-tile:
arch/tile: set CORE_DUMP_USE_REGSET on tile
arch/tile: implement arch_ptrace using user_regset on tile
arch/tile: implement user_regset interface on tile
arch/tile: clean up tile-specific PTRACE_SETOPTIONS
arch/tile: provide PT_FLAGS_COMPAT value in pt_regs
tile/PCI: use for_each_pci_dev to simplify the code
tilegx: remove __init from pci fixup hook
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Neil found that if too_many_isolated() returns true while performing
direct reclaim we can end up waiting for other threads to complete their
direct reclaim. If those threads are allowed to enter the FS or IO to
free memory, but this thread is not, then it is possible that those
threads will be waiting on this thread and so we get a circular deadlock.
some task enters direct reclaim with GFP_KERNEL
=> too_many_isolated() false
=> vmscan and run into dirty pages
=> pageout()
=> take some FS lock
=> fs/block code does GFP_NOIO allocation
=> enter direct reclaim again
=> too_many_isolated() true
=> waiting for others to progress, however the other
tasks may be circular waiting for the FS lock..
The fix is to let !__GFP_IO and !__GFP_FS direct reclaims enjoy higher
priority than normal ones, by lowering the throttle threshold for the
latter.
Allowing ~1/8 isolated pages in normal is large enough. For example, for
a 1GB LRU list, that's ~128MB isolated pages, or 1k blocked tasks (each
isolates 32 4KB pages), or 64 blocked tasks per logical CPU (assuming 16
logical CPUs per NUMA node). So it's not likely some CPU goes idle
waiting (when it could make progress) because of this limit: there are
much more sleeping reclaim tasks than the number of CPU, so the task may
well be blocked by some low level queue/lock anyway.
Now !GFP_IOFS reclaims won't be waiting for GFP_IOFS reclaims to progress.
They will be blocked only when there are too many concurrent !GFP_IOFS
reclaims, however that's very unlikely because the IO-less direct reclaims
is able to progress much more faster, and they won't deadlock each other.
The threshold is raised high enough for them, so that there can be
sufficient parallel progress of !GFP_IOFS reclaims.
[akpm@linux-foundation.org: tweak comment]
Signed-off-by: Wu Fengguang <fengguang.wu@intel.com>
Cc: Torsten Kaiser <just.for.lkml@googlemail.com>
Tested-by: NeilBrown <neilb@suse.de>
Reviewed-by: Minchan Kim <minchan.kim@gmail.com>
Acked-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Acked-by: Rik van Riel <riel@redhat.com>
Cc: Mel Gorman <mel@csn.ul.ie>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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