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The pasic3-leds driver was never in vanilla kernel. Actual configuration
data for a hypothetical driver does not describe hardware completely, so
remove them.
This patch prepare HTC Magician machine code to pasic3-leds driver
addition.
Signed-off-by: Petr Cvek <petr.cvek@tul.cz>
Acked-by: Philipp Zabel <philipp.zabel@gmail.com>
Signed-off-by: Robert Jarzmik <robert.jarzmik@free.fr>
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A PXA27x SoC supports USB device mode, this patch adds support for that.
Signed-off-by: Petr Cvek <petr.cvek@tul.cz>
Acked-by: Philipp Zabel <philipp.zabel@gmail.com>
Signed-off-by: Robert Jarzmik <robert.jarzmik@free.fr>
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HTC Magician contains a MAX1587A voltage regulator for a Vcore supply.
The Vcore regulation is required for a CPU speed switching. This patch adds
declaration for the max1586 driver.
Notice:
- MAX1587A version does not support the V6 (USIM) output.
- A boost resistor was directly measured for a board_id 0x3a.
Signed-off-by: Petr Cvek <petr.cvek@tul.cz>
Signed-off-by: Robert Jarzmik <robert.jarzmik@free.fr>
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This patch changes the comments in the HTC Magician machine source code
to better describe used devices and interfaces.
Signed-off-by: Petr Cvek <petr.cvek@tul.cz>
Signed-off-by: Robert Jarzmik <robert.jarzmik@free.fr>
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This patch moves platform_add_devices() (standard declaration of devices)
outside of the platform specific device declarations. Moving to the end
of the magician_init() clarifies the source code (standard and specific
declaration are not mixed).
Signed-off-by: Petr Cvek <petr.cvek@tul.cz>
Acked-by: Philipp Zabel <philipp.zabel@gmail.com>
Signed-off-by: Robert Jarzmik <robert.jarzmik@free.fr>
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Add a fake regulator, which is required for the correct initialization
of the PWM backlight driver.
Signed-off-by: Petr Cvek <petr.cvek@tul.cz>
Acked-by: Philipp Zabel <philipp.zabel@gmail.com>
[ added a missing include for fixed regulator ]
Signed-off-by: Robert Jarzmik <robert.jarzmik@free.fr>
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Add a debug message for the backlight brightness function.
Signed-off-by: Petr Cvek <petr.cvek@tul.cz>
Signed-off-by: Robert Jarzmik <robert.jarzmik@free.fr>
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Magician STUART port is connected to the infraport and used by the FICP
driver. The FICP driver uses its own definition.
Required for correct initialization of the pxaficp_ir driver after
planned dmaengine conversion.
Signed-off-by: Petr Cvek <petr.cvek@tul.cz>
Signed-off-by: Robert Jarzmik <robert.jarzmik@free.fr>
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USB host ports on the HTC Magician are wrongly enabled. Port 1 is for
bluetooth and port 2 is for OTG (mux in the charger connector).
Signed-off-by: Petr Cvek <petr.cvek@tul.cz>
Signed-off-by: Robert Jarzmik <robert.jarzmik@free.fr>
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Old definition for the physmap-flash driver is incomplete:
- Use of an EGPIO without previous request
- Missing the MTD partitions
This patch fixes it. Read functionality was tested on the machine with
board_id 0x3a. Writing was not tested.
Signed-off-by: Petr Cvek <petr.cvek@tul.cz>
Signed-off-by: Robert Jarzmik <robert.jarzmik@free.fr>
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The pxaficp_ir driver requests a power GPIO for the transceiver internally,
so a global GPIO allocation in magician_init() is redundant.
Signed-off-by: Petr Cvek <petr.cvek@tul.cz>
Signed-off-by: Robert Jarzmik <robert.jarzmik@free.fr>
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This patch changes fast_mode settings for the normal and power I2C
controller on the HTC Magician machine.
Connected device on the Power I2C:
- MAX1587A: working in the fast mode
Connected devices on the Normal I2C:
- UDA1380: working in the fast mode
- OV9640: bus became stuck in the fast mode
The OV9640 is not using a standard I2C protocol, but an SCCB variant. Maybe
it is not fully compatible in the fast mode. Therefore fast mode for normal
I2C is disabled. If you not using the OV9640 then you can enable the fast
mode for the UDA1380.
Signed-off-by: Petr Cvek <petr.cvek@tul.cz>
[included Philipp Zabel's comment change]
Signed-off-by: Robert Jarzmik <robert.jarzmik@free.fr>
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This patch fixes the charging detection functions for pda_power driver
(according to newly discovered EGPIOs) and add NiCd backup accumulator
charging support.
Signed-off-by: Petr Cvek <petr.cvek@tul.cz>
Signed-off-by: Robert Jarzmik <robert.jarzmik@free.fr>
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Change the default Samsung LCD refresh from an unrealistic 117Hz to 50Hz
as no video applications on the HTC Magician can work that fast.
The optimalization lowers the RAM latency at least by 3%.
Signed-off-by: Petr Cvek <petr.cvek@tul.cz>
Acked-by: Philipp Zabel <philipp.zabel@gmail.com>
Signed-off-by: Robert Jarzmik <robert.jarzmik@free.fr>
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This patch renames EGPIOs, which are used for the charging cable presence
and type detection. Old names did not correspond with an observed
functionality (on board_id 0x3a). The behavior is not:
- AC charger
- USB charger
- Cable detection
, but:
- AC/USB type
- Cable detection1
- Cable detection2
This patch fixes a possible typo in the bit offset for the cable detection
EGPIO declaration, too.
Signed-off-by: Petr Cvek <petr.cvek@tul.cz>
Signed-off-by: Robert Jarzmik <robert.jarzmik@free.fr>
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Delays for the Samsung LCD are greater than needed. These values were
extracted from a datasheet.
Signed-off-by: Petr Cvek <petr.cvek@tul.cz>
Acked-by: Philipp Zabel <philipp.zabel@gmail.com>
Signed-off-by: Robert Jarzmik <robert.jarzmik@free.fr>
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This patch renames GPIOs, which are used to control the power lines to
the LCD screen. New names correspond to a real functionality, which was
measured on the HTC Magician board_id 0x3a.
Signed-off-by: Petr Cvek <petr.cvek@tul.cz>
Acked-by: Philipp Zabel <philipp.zabel@gmail.com>
Signed-off-by: Robert Jarzmik <robert.jarzmik@free.fr>
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This patch adds EGPIO pins: Infra transceiver power, NiCD charging and
inserted charger cable.
Signed-off-by: Petr Cvek <petr.cvek@tul.cz>
Acked-by: Philipp Zabel <philipp.zabel@gmail.com>
Signed-off-by: Robert Jarzmik <robert.jarzmik@free.fr>
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This patch changes the description of the LCD power GPIO to be more
specific.
Signed-off-by: Petr Cvek <petr.cvek@tul.cz>
Acked-by: Philipp Zabel <philipp.zabel@gmail.com>
Signed-off-by: Robert Jarzmik <robert.jarzmik@free.fr>
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Optimize the debug messages for the LCD power.
Signed-off-by: Petr Cvek <petr.cvek@tul.cz>
Acked-by: Philipp Zabel <philipp.zabel@gmail.com>
Signed-off-by: Robert Jarzmik <robert.jarzmik@free.fr>
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Print more specific error message for global GPIOs.
Signed-off-by: Petr Cvek <petr.cvek@tul.cz>
Acked-by: Philipp Zabel <philipp.zabel@gmail.com>
Signed-off-by: Robert Jarzmik <robert.jarzmik@free.fr>
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This patch fixes the indentation for the HTC Magician machine definition.
Signed-off-by: Petr Cvek <petr.cvek@tul.cz>
Acked-by: Philipp Zabel <philipp.zabel@gmail.com>
Signed-off-by: Robert Jarzmik <robert.jarzmik@free.fr>
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Use a PWM lookup table to provide the PWM to the pwm-backlight device.
The driver has a legacy code path that is required only because boards
still use the legacy method of requesting PWMs by global ID. Replacing
these usages allows that legacy fallback to be removed.
Cc: Daniel Mack <daniel@zonque.org>
Cc: Haojian Zhuang <haojian.zhuang@gmail.com>
Cc: Robert Jarzmik <robert.jarzmik@free.fr>
Signed-off-by: Thierry Reding <thierry.reding@gmail.com>
Signed-off-by: Robert Jarzmik <robert.jarzmik@free.fr>
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Use a PWM lookup table to provide the PWM to the pwm-backlight device.
The driver has a legacy code path that is required only because boards
still use the legacy method of requesting PWMs by global ID. Replacing
these usages allows that legacy fallback to be removed.
Cc: Daniel Mack <daniel@zonque.org>
Cc: Haojian Zhuang <haojian.zhuang@gmail.com>
Cc: Robert Jarzmik <robert.jarzmik@free.fr>
Signed-off-by: Thierry Reding <thierry.reding@gmail.com>
Signed-off-by: Robert Jarzmik <robert.jarzmik@free.fr>
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Use a PWM lookup table to provide the PWM to the pwm-backlight device.
The driver has a legacy code path that is required only because boards
still use the legacy method of requesting PWMs by global ID. Replacing
these usages allows that legacy fallback to be removed.
Cc: Daniel Mack <daniel@zonque.org>
Cc: Haojian Zhuang <haojian.zhuang@gmail.com>
Cc: Robert Jarzmik <robert.jarzmik@free.fr>
Signed-off-by: Thierry Reding <thierry.reding@gmail.com>
Signed-off-by: Robert Jarzmik <robert.jarzmik@free.fr>
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Use a PWM lookup table to provide the PWM to the pwm-backlight device.
The driver has a legacy code path that is required only because boards
still use the legacy method of requesting PWMs by global ID. Replacing
these usages allows that legacy fallback to be removed.
Cc: Daniel Mack <daniel@zonque.org>
Cc: Haojian Zhuang <haojian.zhuang@gmail.com>
Cc: Robert Jarzmik <robert.jarzmik@free.fr>
Signed-off-by: Thierry Reding <thierry.reding@gmail.com>
Signed-off-by: Robert Jarzmik <robert.jarzmik@free.fr>
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Use a PWM lookup table to provide the PWM to the pwm-backlight device.
The driver has a legacy code path that is required only because boards
still use the legacy method of requesting PWMs by global ID. Replacing
these usages allows that legacy fallback to be removed.
Cc: Daniel Mack <daniel@zonque.org>
Cc: Haojian Zhuang <haojian.zhuang@gmail.com>
Cc: Robert Jarzmik <robert.jarzmik@free.fr>
Signed-off-by: Thierry Reding <thierry.reding@gmail.com>
Signed-off-by: Robert Jarzmik <robert.jarzmik@free.fr>
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Use a PWM lookup table to provide the PWM to the pwm-backlight device.
The driver has a legacy code path that is required only because boards
still use the legacy method of requesting PWMs by global ID. Replacing
these usages allows that legacy fallback to be removed.
Cc: Daniel Mack <daniel@zonque.org>
Cc: Haojian Zhuang <haojian.zhuang@gmail.com>
Cc: Robert Jarzmik <robert.jarzmik@free.fr>
Signed-off-by: Thierry Reding <thierry.reding@gmail.com>
Signed-off-by: Robert Jarzmik <robert.jarzmik@free.fr>
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Use a PWM lookup table to provide the PWM to the pwm-backlight device.
The driver has a legacy code path that is required only because boards
still use the legacy method of requesting PWMs by global ID. Replacing
these usages allows that legacy fallback to be removed.
Cc: Daniel Mack <daniel@zonque.org>
Cc: Haojian Zhuang <haojian.zhuang@gmail.com>
Cc: Robert Jarzmik <robert.jarzmik@free.fr>
Signed-off-by: Thierry Reding <thierry.reding@gmail.com>
Signed-off-by: Robert Jarzmik <robert.jarzmik@free.fr>
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Use a PWM lookup table to provide the PWM to the pwm-backlight device.
The driver has a legacy code path that is required only because boards
still use the legacy method of requesting PWMs by global ID. Replacing
these usages allows that legacy fallback to be removed.
Cc: Daniel Mack <daniel@zonque.org>
Cc: Haojian Zhuang <haojian.zhuang@gmail.com>
Cc: Robert Jarzmik <robert.jarzmik@free.fr>
Signed-off-by: Thierry Reding <thierry.reding@gmail.com>
Signed-off-by: Robert Jarzmik <robert.jarzmik@free.fr>
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Use a PWM lookup table to provide the PWM to the pwm-backlight device.
The driver has a legacy code path that is required only because boards
still use the legacy method of requesting PWMs by global ID. Replacing
these usages allows that legacy fallback to be removed.
Cc: Daniel Mack <daniel@zonque.org>
Cc: Haojian Zhuang <haojian.zhuang@gmail.com>
Cc: Robert Jarzmik <robert.jarzmik@free.fr>
Signed-off-by: Thierry Reding <thierry.reding@gmail.com>
Signed-off-by: Robert Jarzmik <robert.jarzmik@free.fr>
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Use a PWM lookup table to provide the PWM to the pwm-backlight device.
The driver has a legacy code path that is required only because boards
still use the legacy method of requesting PWMs by global ID. Replacing
these usages allows that legacy fallback to be removed.
Cc: Daniel Mack <daniel@zonque.org>
Cc: Haojian Zhuang <haojian.zhuang@gmail.com>
Cc: Robert Jarzmik <robert.jarzmik@free.fr>
Signed-off-by: Thierry Reding <thierry.reding@gmail.com>
Signed-off-by: Robert Jarzmik <robert.jarzmik@free.fr>
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Use a PWM lookup table to provide the PWM to the pwm-backlight device.
The driver has a legacy code path that is required only because boards
still use the legacy method of requesting PWMs by global ID. Replacing
these usages allows that legacy fallback to be removed.
Cc: Daniel Mack <daniel@zonque.org>
Cc: Haojian Zhuang <haojian.zhuang@gmail.com>
Cc: Robert Jarzmik <robert.jarzmik@free.fr>
Signed-off-by: Thierry Reding <thierry.reding@gmail.com>
Signed-off-by: Robert Jarzmik <robert.jarzmik@free.fr>
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Use a PWM lookup table to provide the PWM to the pwm-backlight device.
The driver has a legacy code path that is required only because boards
still use the legacy method of requesting PWMs by global ID. Replacing
these usages allows that legacy fallback to be removed.
Cc: Daniel Mack <daniel@zonque.org>
Cc: Haojian Zhuang <haojian.zhuang@gmail.com>
Cc: Robert Jarzmik <robert.jarzmik@free.fr>
Signed-off-by: Thierry Reding <thierry.reding@gmail.com>
[ split pwm_remove_table() call on 2 lines ]
Signed-off-by: Robert Jarzmik <robert.jarzmik@free.fr>
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Use a PWM lookup table to provide the PWM to the pwm-backlight device.
The driver has a legacy code path that is required only because boards
still use the legacy method of requesting PWMs by global ID. Replacing
these usages allows that legacy fallback to be removed.
Cc: Daniel Mack <daniel@zonque.org>
Cc: Haojian Zhuang <haojian.zhuang@gmail.com>
Cc: Robert Jarzmik <robert.jarzmik@free.fr>
Signed-off-by: Thierry Reding <thierry.reding@gmail.com>
Acked-by: Philipp Zabel <philipp.zabel@gmail.com>
Signed-off-by: Robert Jarzmik <robert.jarzmik@free.fr>
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Use a PWM lookup table to provide the PWM to the pwm-backlight device.
The driver has a legacy code path that is required only because boards
still use the legacy method of requesting PWMs by global ID. Replacing
these usages allows that legacy fallback to be removed.
Cc: Daniel Mack <daniel@zonque.org>
Cc: Haojian Zhuang <haojian.zhuang@gmail.com>
Cc: Robert Jarzmik <robert.jarzmik@free.fr>
Signed-off-by: Thierry Reding <thierry.reding@gmail.com>
Signed-off-by: Robert Jarzmik <robert.jarzmik@free.fr>
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The ID and period for the backlight PWM are obtained from a PWM lookup
table, so the corresponding values don't need to be duplicated into the
platform data.
Cc: Daniel Mack <daniel@zonque.org>
Cc: Haojian Zhuang <haojian.zhuang@gmail.com>
Cc: Robert Jarzmik <robert.jarzmik@free.fr>
Signed-off-by: Thierry Reding <thierry.reding@gmail.com>
Acked-by: Philipp Zabel <philipp.zabel@gmail.com>
Signed-off-by: Robert Jarzmik <robert.jarzmik@free.fr>
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Use a PWM lookup table to provide the PWM to the pwm-backlight device.
The driver has a legacy code path that is required only because boards
still use the legacy method of requesting PWMs by global ID. Replacing
these usages allows that legacy fallback to be removed.
Cc: Daniel Mack <daniel@zonque.org>
Cc: Haojian Zhuang <haojian.zhuang@gmail.com>
Cc: Robert Jarzmik <robert.jarzmik@free.fr>
Signed-off-by: Thierry Reding <thierry.reding@gmail.com>
Signed-off-by: Robert Jarzmik <robert.jarzmik@free.fr>
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Use a PWM lookup table to provide the PWM to the pwm-backlight device.
The driver has a legacy code path that is required only because boards
still use the legacy method of requesting PWMs by global ID. Replacing
these usages allows that legacy fallback to be removed.
Cc: Daniel Mack <daniel@zonque.org>
Cc: Haojian Zhuang <haojian.zhuang@gmail.com>
Cc: Robert Jarzmik <robert.jarzmik@free.fr>
Signed-off-by: Thierry Reding <thierry.reding@gmail.com>
Signed-off-by: Robert Jarzmik <robert.jarzmik@free.fr>
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The mioa701 is using the wm9713 for audio, battery and touchscreen. Add
the missing audio part, which disappeared.
Signed-off-by: Robert Jarzmik <robert.jarzmik@free.fr>
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Add io memory and dma requestor lines to the irda pxa device. This is
part of the conversion of pxaficp_ir to dmaengine, and to shrink its
adherence to 'mach' includes.
Signed-off-by: Robert Jarzmik <robert.jarzmik@free.fr>
Tested-by: Petr Cvek <petr.cvek@tul.cz>
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Use for struct pxa2xx_spi_master clock_enable field was removed years ago
from the pxa2xx-spi driver by the commit 2f1a74e5a2de ("[ARM] pxa: make
pxa2xx_spi driver use ssp_request()/ssp_free()").
Therefore remove it from structure definition, documentation and from
couple affected board files.
Signed-off-by: Jarkko Nikula <jarkko.nikula@linux.intel.com>
Acked-by: Mark Brown <broonie@kernel.org>
Signed-off-by: Robert Jarzmik <robert.jarzmik@free.fr>
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git://git.kernel.org/pub/scm/linux/kernel/git/jesper/cris
Pull CRIS updates from Jesper Nilsson:
"Mostly removal of old cruft of which we can use a generic version, or
fixes for code not commonly run in the cris port, but also additions
to enable some good debug"
* tag 'cris-for-4.3' of git://git.kernel.org/pub/scm/linux/kernel/git/jesper/cris: (25 commits)
CRISv10: delete unused lib/dmacopy.c
CRISv10: delete unused lib/old_checksum.c
CRIS: fix switch_mm() lockdep splat
CRISv32: enable LOCKDEP_SUPPORT
CRIS: add STACKTRACE_SUPPORT
CRISv32: annotate irq enable in idle loop
CRISv32: add support for irqflags tracing
CRIS: UAPI: use generic types.h
CRIS: UAPI: use generic shmbuf.h
CRIS: UAPI: use generic msgbuf.h
CRIS: UAPI: use generic socket.h
CRIS: UAPI: use generic sembuf.h
CRIS: UAPI: use generic sockios.h
CRIS: UAPI: use generic auxvec.h
CRIS: UAPI: use generic headers via Kbuild
CRIS: UAPI: fix elf.h export
CRIS: don't make asm/elf.h depend on asm/user.h
CRIS: UAPI: fix ptrace.h
CRISv32: Squash compile warnings for axisflashmap
CRISv32: Add GPIO driver to the default configs
...
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Merge fourth patch-bomb from Andrew Morton:
- sys_membarier syscall
- seq_file interface changes
- a few misc fixups
* emailed patches from Andrew Morton <akpm@linux-foundation.org>:
revert "ocfs2/dlm: use list_for_each_entry instead of list_for_each"
mm/early_ioremap: add explicit #include of asm/early_ioremap.h
fs/seq_file: convert int seq_vprint/seq_printf/etc... returns to void
selftests: enhance membarrier syscall test
selftests: add membarrier syscall test
sys_membarrier(): system-wide memory barrier (generic, x86)
MODSIGN: fix a compilation warning in extract-cert
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Newer bitfiles needs the reduced clk even for SMP builds
Cc: <stable@vger.kernel.org> #4.2
Signed-off-by: Vineet Gupta <vgupta@synopsys.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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Here is an implementation of a new system call, sys_membarrier(), which
executes a memory barrier on all threads running on the system. It is
implemented by calling synchronize_sched(). It can be used to
distribute the cost of user-space memory barriers asymmetrically by
transforming pairs of memory barriers into pairs consisting of
sys_membarrier() and a compiler barrier. For synchronization primitives
that distinguish between read-side and write-side (e.g. userspace RCU
[1], rwlocks), the read-side can be accelerated significantly by moving
the bulk of the memory barrier overhead to the write-side.
The existing applications of which I am aware that would be improved by
this system call are as follows:
* Through Userspace RCU library (http://urcu.so)
- DNS server (Knot DNS) https://www.knot-dns.cz/
- Network sniffer (http://netsniff-ng.org/)
- Distributed object storage (https://sheepdog.github.io/sheepdog/)
- User-space tracing (http://lttng.org)
- Network storage system (https://www.gluster.org/)
- Virtual routers (https://events.linuxfoundation.org/sites/events/files/slides/DPDK_RCU_0MQ.pdf)
- Financial software (https://lkml.org/lkml/2015/3/23/189)
Those projects use RCU in userspace to increase read-side speed and
scalability compared to locking. Especially in the case of RCU used by
libraries, sys_membarrier can speed up the read-side by moving the bulk of
the memory barrier cost to synchronize_rcu().
* Direct users of sys_membarrier
- core dotnet garbage collector (https://github.com/dotnet/coreclr/issues/198)
Microsoft core dotnet GC developers are planning to use the mprotect()
side-effect of issuing memory barriers through IPIs as a way to implement
Windows FlushProcessWriteBuffers() on Linux. They are referring to
sys_membarrier in their github thread, specifically stating that
sys_membarrier() is what they are looking for.
To explain the benefit of this scheme, let's introduce two example threads:
Thread A (non-frequent, e.g. executing liburcu synchronize_rcu())
Thread B (frequent, e.g. executing liburcu
rcu_read_lock()/rcu_read_unlock())
In a scheme where all smp_mb() in thread A are ordering memory accesses
with respect to smp_mb() present in Thread B, we can change each
smp_mb() within Thread A into calls to sys_membarrier() and each
smp_mb() within Thread B into compiler barriers "barrier()".
Before the change, we had, for each smp_mb() pairs:
Thread A Thread B
previous mem accesses previous mem accesses
smp_mb() smp_mb()
following mem accesses following mem accesses
After the change, these pairs become:
Thread A Thread B
prev mem accesses prev mem accesses
sys_membarrier() barrier()
follow mem accesses follow mem accesses
As we can see, there are two possible scenarios: either Thread B memory
accesses do not happen concurrently with Thread A accesses (1), or they
do (2).
1) Non-concurrent Thread A vs Thread B accesses:
Thread A Thread B
prev mem accesses
sys_membarrier()
follow mem accesses
prev mem accesses
barrier()
follow mem accesses
In this case, thread B accesses will be weakly ordered. This is OK,
because at that point, thread A is not particularly interested in
ordering them with respect to its own accesses.
2) Concurrent Thread A vs Thread B accesses
Thread A Thread B
prev mem accesses prev mem accesses
sys_membarrier() barrier()
follow mem accesses follow mem accesses
In this case, thread B accesses, which are ensured to be in program
order thanks to the compiler barrier, will be "upgraded" to full
smp_mb() by synchronize_sched().
* Benchmarks
On Intel Xeon E5405 (8 cores)
(one thread is calling sys_membarrier, the other 7 threads are busy
looping)
1000 non-expedited sys_membarrier calls in 33s =3D 33 milliseconds/call.
* User-space user of this system call: Userspace RCU library
Both the signal-based and the sys_membarrier userspace RCU schemes
permit us to remove the memory barrier from the userspace RCU
rcu_read_lock() and rcu_read_unlock() primitives, thus significantly
accelerating them. These memory barriers are replaced by compiler
barriers on the read-side, and all matching memory barriers on the
write-side are turned into an invocation of a memory barrier on all
active threads in the process. By letting the kernel perform this
synchronization rather than dumbly sending a signal to every process
threads (as we currently do), we diminish the number of unnecessary wake
ups and only issue the memory barriers on active threads. Non-running
threads do not need to execute such barrier anyway, because these are
implied by the scheduler context switches.
Results in liburcu:
Operations in 10s, 6 readers, 2 writers:
memory barriers in reader: 1701557485 reads, 2202847 writes
signal-based scheme: 9830061167 reads, 6700 writes
sys_membarrier: 9952759104 reads, 425 writes
sys_membarrier (dyn. check): 7970328887 reads, 425 writes
The dynamic sys_membarrier availability check adds some overhead to
the read-side compared to the signal-based scheme, but besides that,
sys_membarrier slightly outperforms the signal-based scheme. However,
this non-expedited sys_membarrier implementation has a much slower grace
period than signal and memory barrier schemes.
Besides diminishing the number of wake-ups, one major advantage of the
membarrier system call over the signal-based scheme is that it does not
need to reserve a signal. This plays much more nicely with libraries,
and with processes injected into for tracing purposes, for which we
cannot expect that signals will be unused by the application.
An expedited version of this system call can be added later on to speed
up the grace period. Its implementation will likely depend on reading
the cpu_curr()->mm without holding each CPU's rq lock.
This patch adds the system call to x86 and to asm-generic.
[1] http://urcu.so
membarrier(2) man page:
MEMBARRIER(2) Linux Programmer's Manual MEMBARRIER(2)
NAME
membarrier - issue memory barriers on a set of threads
SYNOPSIS
#include <linux/membarrier.h>
int membarrier(int cmd, int flags);
DESCRIPTION
The cmd argument is one of the following:
MEMBARRIER_CMD_QUERY
Query the set of supported commands. It returns a bitmask of
supported commands.
MEMBARRIER_CMD_SHARED
Execute a memory barrier on all threads running on the system.
Upon return from system call, the caller thread is ensured that
all running threads have passed through a state where all memory
accesses to user-space addresses match program order between
entry to and return from the system call (non-running threads
are de facto in such a state). This covers threads from all pro=E2=80=90
cesses running on the system. This command returns 0.
The flags argument needs to be 0. For future extensions.
All memory accesses performed in program order from each targeted
thread is guaranteed to be ordered with respect to sys_membarrier(). If
we use the semantic "barrier()" to represent a compiler barrier forcing
memory accesses to be performed in program order across the barrier,
and smp_mb() to represent explicit memory barriers forcing full memory
ordering across the barrier, we have the following ordering table for
each pair of barrier(), sys_membarrier() and smp_mb():
The pair ordering is detailed as (O: ordered, X: not ordered):
barrier() smp_mb() sys_membarrier()
barrier() X X O
smp_mb() X O O
sys_membarrier() O O O
RETURN VALUE
On success, these system calls return zero. On error, -1 is returned,
and errno is set appropriately. For a given command, with flags
argument set to 0, this system call is guaranteed to always return the
same value until reboot.
ERRORS
ENOSYS System call is not implemented.
EINVAL Invalid arguments.
Linux 2015-04-15 MEMBARRIER(2)
Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Reviewed-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Reviewed-by: Josh Triplett <josh@joshtriplett.org>
Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Nicholas Miell <nmiell@comcast.net>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Alan Cox <gnomes@lxorguk.ukuu.org.uk>
Cc: Lai Jiangshan <laijs@cn.fujitsu.com>
Cc: Stephen Hemminger <stephen@networkplumber.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: David Howells <dhowells@redhat.com>
Cc: Pranith Kumar <bobby.prani@gmail.com>
Cc: Michael Kerrisk <mtk.manpages@gmail.com>
Cc: Shuah Khan <shuahkh@osg.samsung.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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Merge third patch-bomb from Andrew Morton:
- even more of the rest of MM
- lib/ updates
- checkpatch updates
- small changes to a few scruffy filesystems
- kmod fixes/cleanups
- kexec updates
- a dma-mapping cleanup series from hch
* emailed patches from Andrew Morton <akpm@linux-foundation.org>: (81 commits)
dma-mapping: consolidate dma_set_mask
dma-mapping: consolidate dma_supported
dma-mapping: cosolidate dma_mapping_error
dma-mapping: consolidate dma_{alloc,free}_noncoherent
dma-mapping: consolidate dma_{alloc,free}_{attrs,coherent}
mm: use vma_is_anonymous() in create_huge_pmd() and wp_huge_pmd()
mm: make sure all file VMAs have ->vm_ops set
mm, mpx: add "vm_flags_t vm_flags" arg to do_mmap_pgoff()
mm: mark most vm_operations_struct const
namei: fix warning while make xmldocs caused by namei.c
ipc: convert invalid scenarios to use WARN_ON
zlib_deflate/deftree: remove bi_reverse()
lib/decompress_unlzma: Do a NULL check for pointer
lib/decompressors: use real out buf size for gunzip with kernel
fs/affs: make root lookup from blkdev logical size
sysctl: fix int -> unsigned long assignments in INT_MIN case
kexec: export KERNEL_IMAGE_SIZE to vmcoreinfo
kexec: align crash_notes allocation to make it be inside one physical page
kexec: remove unnecessary test in kimage_alloc_crash_control_pages()
kexec: split kexec_load syscall from kexec core code
...
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git://git.kernel.org/pub/scm/linux/kernel/git/arm/arm-soc
Pull late ARM SoC updates from Kevin Hilman:
"This is a collection of a few late fixes and other misc stuff that had
dependencies on things being merged from other trees.
The bulk of the changes are for samsung/exynos SoCs for some changes
that needed a few minor reworks so ended up a bit late. The others
are mainly for qcom SoCs: a couple fixes and some DTS updates"
* tag 'armsoc-late' of git://git.kernel.org/pub/scm/linux/kernel/git/arm/arm-soc: (37 commits)
ARM: multi_v7_defconfig: Enable PBIAS regulator
soc: qcom: smd: Correct fBLOCKREADINTR handling
soc: qcom: smd: Use correct remote processor ID
soc: qcom: smem: Fix errant private access
ARM: dts: qcom: msm8974-sony-xperia-honami: Use stdout-path
ARM: dts: qcom: msm8960-cdp: Use stdout-path
ARM: dts: qcom: msm8660-surf: Use stdout-path
ARM: dts: qcom: ipq8064-ap148: Use stdout-path
ARM: dts: qcom: apq8084-mtp: Use stdout-path
ARM: dts: qcom: apq8084-ifc6540: Use stdout-path
ARM: dts: qcom: apq8074-dragonboard: Use stdout-path
ARM: dts: qcom: apq8064-ifc6410: Use stdout-path
ARM: dts: qcom: apq8064-cm-qs600: Use stdout-path
ARM: dts: qcom: Label serial nodes for aliasing and stdout-path
reset: ath79: Fix missing spin_lock_init
reset: Add (devm_)reset_control_get stub functions
ARM: EXYNOS: switch to using generic cpufreq driver for exynos4x12
cpufreq: exynos: Remove unselectable rule for arm-exynos-cpufreq.o
ARM: dts: add iommu property to JPEG device for exynos4
ARM: dts: enable SPI1 for exynos4412-odroidu3
...
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Pull more kvm updates from Paolo Bonzini:
"ARM:
- Full debug support for arm64
- Active state switching for timer interrupts
- Lazy FP/SIMD save/restore for arm64
- Generic ARMv8 target
PPC:
- Book3S: A few bug fixes
- Book3S: Allow micro-threading on POWER8
x86:
- Compiler warnings
Generic:
- Adaptive polling for guest halt"
* tag 'for-linus' of git://git.kernel.org/pub/scm/virt/kvm/kvm: (49 commits)
kvm: irqchip: fix memory leak
kvm: move new trace event outside #ifdef CONFIG_KVM_ASYNC_PF
KVM: trace kvm_halt_poll_ns grow/shrink
KVM: dynamic halt-polling
KVM: make halt_poll_ns per-vCPU
Silence compiler warning in arch/x86/kvm/emulate.c
kvm: compile process_smi_save_seg_64() only for x86_64
KVM: x86: avoid uninitialized variable warning
KVM: PPC: Book3S: Fix typo in top comment about locking
KVM: PPC: Book3S: Fix size of the PSPB register
KVM: PPC: Book3S HV: Exit on H_DOORBELL if HOST_IPI is set
KVM: PPC: Book3S HV: Fix race in starting secondary threads
KVM: PPC: Book3S: correct width in XER handling
KVM: PPC: Book3S HV: Fix preempted vcore stolen time calculation
KVM: PPC: Book3S HV: Fix preempted vcore list locking
KVM: PPC: Book3S HV: Implement H_CLEAR_REF and H_CLEAR_MOD
KVM: PPC: Book3S HV: Fix bug in dirty page tracking
KVM: PPC: Book3S HV: Fix race in reading change bit when removing HPTE
KVM: PPC: Book3S HV: Implement dynamic micro-threading on POWER8
KVM: PPC: Book3S HV: Make use of unused threads when running guests
...
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git://git.kernel.org/pub/scm/linux/kernel/git/xen/tip
Pull xen terminology fixes from David Vrabel:
"Use the correct GFN/BFN terms more consistently"
* tag 'for-linus-4.3-rc0b-tag' of git://git.kernel.org/pub/scm/linux/kernel/git/xen/tip:
xen/xenbus: Rename the variable xen_store_mfn to xen_store_gfn
xen/privcmd: Further s/MFN/GFN/ clean-up
hvc/xen: Further s/MFN/GFN clean-up
video/xen-fbfront: Further s/MFN/GFN clean-up
xen/tmem: Use xen_page_to_gfn rather than pfn_to_gfn
xen: Use correctly the Xen memory terminologies
arm/xen: implement correctly pfn_to_mfn
xen: Make clear that swiotlb and biomerge are dealing with DMA address
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