linux-toradex.git/drivers/cpuidle/sysfs.c, branch v3.10.10

cpuidle: fix number of initialized/destroyed states

2013-01-11T22:20:09+00:00

Commit bf4d1b5ddb78f86078ac6ae0415802d5f0c68f92 (cpuidle: support
multiple drivers) changed the number of initialized state kobjects
in cpuidle_add_state_sysfs() from device->state_count to
drv->state_count, but left device->state_count in
cpuidle_remove_state_sysfs().  The values of these two fields may be
different, in which case a NULL pointer dereference may happen in
cpuidle_remove_state_sysfs(), for example.  Fix this problem by making
cpuidle_add_state_sysfs() use device->state_count too (which restores
the original behavior of it).

[rjw: Changelog]
Signed-off-by: Krzysztof Mazur 
Acked-by: Daniel Lezcano 
Signed-off-by: Rafael J. Wysocki

cpuidle: support multiple drivers

2012-11-14T23:34:23+00:00

With the tegra3 and the big.LITTLE [1] new architectures, several cpus
with different characteristics (latencies and states) can co-exists on the
system.

The cpuidle framework has the limitation of handling only identical cpus.

This patch removes this limitation by introducing the multiple driver support
for cpuidle.

This option is configurable at compile time and should be enabled for the
architectures mentioned above. So there is no impact for the other platforms
if the option is disabled. The option defaults to 'n'. Note the multiple drivers
support is also compatible with the existing drivers, even if just one driver is
needed, all the cpu will be tied to this driver using an extra small chunk of
processor memory.

The multiple driver support use a per-cpu driver pointer instead of a global
variable and the accessor to this variable are done from a cpu context.

In order to keep the compatibility with the existing drivers, the function
'cpuidle_register_driver' and 'cpuidle_unregister_driver' will register
the specified driver for all the cpus.

The semantic for the output of /sys/devices/system/cpu/cpuidle/current_driver
remains the same except the driver name will be related to the current cpu.

The /sys/devices/system/cpu/cpu[0-9]/cpuidle/driver/name files are added
allowing to read the per cpu driver name.

[1] http://lwn.net/Articles/481055/

Signed-off-by: Daniel Lezcano 
Acked-by: Peter De Schrijver 
Signed-off-by: Rafael J. Wysocki

cpuidle: fixup device.h header in cpuidle.h

2012-11-14T23:34:21+00:00

The "struct device" is only used in sysfs.c.

The other .c files including the private header "cpuidle.h"
do not need to pull the entire headers tree from there as they
don't manipulate the "struct device".

This patch fixes this by moving the header inclusion to sysfs.c
and adding a forward declaration for the struct device.

The number of lines generated by the preprocesor:
Without this patch : 17269 loc
With this patch : 16446 loc

Signed-off-by: Daniel Lezcano 
Signed-off-by: Rafael J. Wysocki

cpuidle / sysfs: move structure declaration into the sysfs.c file

2012-11-14T23:34:21+00:00

The structure cpuidle_state_kobj is not used anywhere except
in the sysfs.c file. The definition of this structure is not
needed in the cpuidle header file. This patch moves it to the
sysfs.c file in order to encapsulate the code a bit more.

Signed-off-by: Daniel Lezcano 
Signed-off-by: Rafael J. Wysocki

cpuidle / sysfs: move kobj initialization in the syfs file

2012-11-14T23:34:19+00:00

Move the kobj initialization and completion in the sysfs.c
and encapsulate the code more.

Signed-off-by: Daniel Lezcano 
Signed-off-by: Rafael J. Wysocki

cpuidle / sysfs: change function parameter

2012-11-14T23:34:19+00:00

The function needs the cpuidle_device which is initially passed to the
caller.

The current code gets the struct device from the struct cpuidle_device,
pass it the cpuidle_add_sysfs function. This function calls
per_cpu(cpuidle_devices, cpu) to get the cpuidle_device.

This patch pass the cpuidle_device instead and simplify the code.

Signed-off-by: Daniel Lezcano 
Signed-off-by: Rafael J. Wysocki

cpuidle: move field disable from per-driver to per-cpu

2012-07-03T17:05:31+00:00

Andrew J.Schorr raises a question.  When he changes the disable setting on
a single CPU, it affects all the other CPUs.  Basically, currently, the
disable field is per-driver instead of per-cpu.  All the C states of the
same driver are shared by all CPU in the same machine.

The patch changes the `disable' field to per-cpu, so we could set this
separately for each cpu.

Signed-off-by: ShuoX Liu 
Reported-by: Andrew J.Schorr 
Reviewed-by: Yanmin Zhang 
Signed-off-by: Andrew Morton 
Signed-off-by: Rafael J. Wysocki

cpuidle: add a sysfs entry to disable specific C state for debug purpose.

2012-03-30T05:52:58+00:00

Some C states of new CPU might be not good.  One reason is BIOS might
configure them incorrectly.  To help developers root cause it quickly, the
patch adds a new sysfs entry, so developers could disable specific C state
manually.

In addition, C state might have much impact on performance tuning, as it
takes much time to enter/exit C states, which might delay interrupt
processing.  With the new debug option, developers could check if a deep C
state could impact performance and how much impact it could cause.

Also add this option in Documentation/cpuidle/sysfs.txt.

[akpm@linux-foundation.org: check kstrtol return value]
Signed-off-by: ShuoX Liu 
Reviewed-by: Yanmin Zhang 
Reviewed-and-Tested-by: Deepthi Dharwar 
Signed-off-by: Andrew Morton 
Signed-off-by: Len Brown

cpu: convert 'cpu' and 'machinecheck' sysdev_class to a regular subsystem

2011-12-21T22:29:42+00:00

This moves the 'cpu sysdev_class' over to a regular 'cpu' subsystem
and converts the devices to regular devices. The sysdev drivers are
implemented as subsystem interfaces now.

After all sysdev classes are ported to regular driver core entities, the
sysdev implementation will be entirely removed from the kernel.

Userspace relies on events and generic sysfs subsystem infrastructure
from sysdev devices, which are made available with this conversion.

Cc: Haavard Skinnemoen 
Cc: Hans-Christian Egtvedt 
Cc: Tony Luck 
Cc: Fenghua Yu 
Cc: Arnd Bergmann 
Cc: Benjamin Herrenschmidt 
Cc: Paul Mackerras 
Cc: Martin Schwidefsky 
Cc: Heiko Carstens 
Cc: Paul Mundt 
Cc: "David S. Miller" 
Cc: Chris Metcalf 
Cc: Thomas Gleixner 
Cc: Ingo Molnar 
Cc: "H. Peter Anvin" 
Cc: Borislav Petkov 
Cc: Tigran Aivazian 
Cc: Len Brown 
Cc: Zhang Rui 
Cc: Dave Jones 
Cc: Peter Zijlstra 
Cc: Russell King 
Cc: Andrew Morton 
Cc: Arjan van de Ven 
Cc: "Rafael J. Wysocki" 
Cc: "Srivatsa S. Bhat" 
Signed-off-by: Kay Sievers 
Signed-off-by: Greg Kroah-Hartman

cpuidle: Single/Global registration of idle states

2011-11-07T02:13:58+00:00

This patch makes the cpuidle_states structure global (single copy)
instead of per-cpu. The statistics needed on per-cpu basis
by the governor are kept per-cpu. This simplifies the cpuidle
subsystem as state registration is done by single cpu only.
Having single copy of cpuidle_states saves memory. Rare case
of asymmetric C-states can be handled within the cpuidle driver
and architectures such as POWER do not have asymmetric C-states.

Having single/global registration of all the idle states,
dynamic C-state transitions on x86 are handled by
the boot cpu. Here, the boot cpu  would disable all the devices,
re-populate the states and later enable all the devices,
irrespective of the cpu that would receive the notification first.

Reference:
https://lkml.org/lkml/2011/4/25/83

Signed-off-by: Deepthi Dharwar 
Signed-off-by: Trinabh Gupta 
Tested-by: Jean Pihet 
Reviewed-by: Kevin Hilman 
Acked-by: Arjan van de Ven 
Acked-by: Kevin Hilman 
Signed-off-by: Len Brown