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  1. 26 Feb, 2010 10 commits
    • Rafael J. Wysocki's avatar
      PM: Allow device drivers to use dpm_wait() · f8824cee
      Rafael J. Wysocki authored 
      There are some dependencies between devices (in particular, between
EHCI USB controllers and their OHCI/UHCI siblings) which are not
reflected by the structure of the device tree.  With synchronous
suspend and resume these dependencies are taken into accout
automatically, because the devices in question are always registered
in the right order, but to meet these constraints with asynchronous
suspend and resume the drivers of these devices will need to use
dpm_wait() in their suspend/resume routines, so introduce a helper
function allowing them to do that.
Signed-off-by: default avatarRafael J. Wysocki <rjw@sisk.pl>
      f8824cee
    • Rafael J. Wysocki's avatar
      PM: Start asynchronous resume threads upfront · 97df8c12
      Rafael J. Wysocki authored 
      It has been shown by testing that total device resume time can be
reduced significantly (by as much as 50% or more) if the async
threads executing some devices' resume routines are all started
before the main resume thread starts to handle the "synchronous"
devices.

This is a consequence of the fact that the slowest devices tend to be
located at the end of dpm_list, so their resume routines are started
very late.  Consequently, they have to wait for all the preceding
"synchronous" devices before their resume routines can be started
by the main resume thread, even if they are "asynchronous".  By
starting their async threads upfront we effectively move those
devices towards the beginning of dpm_list, without breaking their
ordering with respect to their parents and children.  As a result,
their resume routines are started much earlier and we are able to
save much more device resume time this way.
Signed-off-by: default avatarRafael J. Wysocki <rjw@sisk.pl>
      97df8c12
    • Rafael J. Wysocki's avatar
      PM: Add facility for advanced testing of async suspend/resume · 5a2eb858
      Rafael J. Wysocki authored 
      Add configuration switch CONFIG_PM_ADVANCED_DEBUG for compiling in
extra PM debugging/testing code allowing one to access some
PM-related attributes of devices from the user space via sysfs.

If CONFIG_PM_ADVANCED_DEBUG is set, add sysfs attribute power/async
for every device allowing the user space to access the device's
power.async_suspend flag and modify it, if desired.
Signed-off-by: default avatarRafael J. Wysocki <rjw@sisk.pl>
      5a2eb858
    • Rafael J. Wysocki's avatar
      PM: Add a switch for disabling/enabling asynchronous suspend/resume · 0e06b4a8
      Rafael J. Wysocki authored 
      Add sysfs attribute /sys/power/pm_async allowing the user space to
disable/enable asynchronous suspend/resume of devices.
Signed-off-by: default avatarRafael J. Wysocki <rjw@sisk.pl>
      0e06b4a8
    • Rafael J. Wysocki's avatar
      PM: Asynchronous suspend and resume of devices · 5af84b82
      Rafael J. Wysocki authored 
      Theoretically, the total time of system sleep transitions (suspend
to RAM, hibernation) can be reduced by running suspend and resume
callbacks of device drivers in parallel with each other.  However,
there are dependencies between devices such that we're not allowed
to suspend the parent of a device before suspending the device
itself.  Analogously, we're not allowed to resume a device before
resuming its parent.

The most straightforward way to take these dependencies into accout
is to start the async threads used for suspending and resuming
devices at the core level, so that async_schedule() is called for
each suspend and resume callback supposed to be executed
asynchronously.

For this purpose, introduce a new device flag, power.async_suspend,
used to mark the devices whose suspend and resume callbacks are to be
executed asynchronously (ie. in parallel with the main suspend/resume
thread and possibly in parallel with each other) and helper function
device_enable_async_suspend() allowing one to set power.async_suspend
for given device (power.async_suspend is unset by default for all
devices).  For each device with the power.async_suspend flag set the
PM core will use async_schedule() to execute its suspend and resume
callbacks.

The async threads started for different devices as a result of
calling async_schedule() are synchronized with each other and with
the main suspend/resume thread with the help of completions, in the
following way:
(1) There is a completion, power.completion, for each device object.
(2) Each device's completion is reset before calling async_schedule()
    for the device or, in the case of devices with the
    power.async_suspend flags unset, before executing the device's
    suspend and resume callbacks.
(3) During suspend, right before running the bus type, device type
    and device class suspend callbacks for the device, the PM core
    waits for the completions of all the device's children to be
    completed.
(4) During resume, right before running the bus type, device type and
    device class resume callbacks for the device, the PM core waits
    for the completion of the device's parent to be completed.
(5) The PM core completes power.completion for each device right
    after the bus type, device type and device class suspend (or
    resume) callbacks executed for the device have returned.
Signed-off-by: default avatarRafael J. Wysocki <rjw@sisk.pl>
      5af84b82
    • Rafael J. Wysocki's avatar
      PM: Add parent information to timing messages · 8cc6b39f
      Rafael J. Wysocki authored 
      Add parent information to the messages printed by the suspend/resume
core when initcall_debug is set.
Signed-off-by: default avatarRafael J. Wysocki <rjw@sisk.pl>
      8cc6b39f
    • Rafael J. Wysocki's avatar
      PM: Document device power attributes in sysfs · 971cb7fb
      Rafael J. Wysocki authored 
      There are sysfs attributes in /sys/devices/.../power/ that haven't
been documented yet in Documentation/ABI/.  Document them as
appropriate.
Signed-off-by: default avatarRafael J. Wysocki <rjw@sisk.pl>
      971cb7fb
    • Rafael J. Wysocki's avatar
      PM / Runtime: Add sysfs switch for disabling device run-time PM · 53823639
      Rafael J. Wysocki authored 
      Add new device sysfs attribute, power/control, allowing the user
space to block the run-time power management of the devices.  If this
attribute is set to "on", the driver of the device won't be able to power
manage it at run time (without breaking the rules) and the device will
always be in the full power state (except when the entire system goes
into a sleep state).
Signed-off-by: default avatarRafael J. Wysocki <rjw@sisk.pl>
Acked-by: default avatarAlan Stern <stern@rowland.harvard.edu>
      53823639
    • Linus Torvalds's avatar
      Merge branch 'linux-next' of git://git.kernel.org/pub/scm/linux/kernel/git/jbarnes/pci-2.6 · 68c6b859
      Linus Torvalds authored 
      * 'linux-next' of git://git.kernel.org/pub/scm/linux/kernel/git/jbarnes/pci-2.6: (48 commits)
  x86/PCI: Prevent mmconfig memory corruption
  ACPI: Use GPE reference counting to support shared GPEs
  x86/PCI: use host bridge _CRS info by default on 2008 and newer machines
  PCI: augment bus resource table with a list
  PCI: add pci_bus_for_each_resource(), remove direct bus->resource[] refs
  PCI: read bridge windows before filling in subtractive decode resources
  PCI: split up pci_read_bridge_bases()
  PCIe PME: use pci_pcie_cap()
  PCI PM: Run-time callbacks for PCI bus type
  PCIe PME: use pci_is_pcie()
  PCI / ACPI / PM: Platform support for PCI PME wake-up
  ACPI / ACPICA: Multiple system notify handlers per device
  ACPI / PM: Add more run-time wake-up fields
  ACPI: Use GPE reference counting to support shared GPEs
  PCI PM: Make it possible to force using INTx for PCIe PME signaling
  PCI PM: PCIe PME root port service driver
  PCI PM: Add function for checking PME status of devices
  PCI: mark is_pcie obsolete
  PCI: set PCI_PREF_RANGE_TYPE_64 in pci_bridge_check_ranges
  PCI: pciehp: second try to get big range for pcie devices
  ...
      68c6b859
    • Linus Torvalds's avatar
      Lower USB storage settling delay to something more reasonable · a4a47bc0
      Linus Torvalds authored 
      The five-second delay can be rather annoying, and makes the system
appear much less responsive when you connect a USB drive.

It's also not entirely clear that it is needed - the settling delay has
at least historically been an issue on some Apple iPods, for example,
and some devices have been reported to need even more than the old 5s
delay.

But before we penalize them all, let's see how bad it really is.  Some
of the reasons for long delays seem to be actual historical kernel bugs
that should probably never have been papered over with a delay in the
first place (there's a Ubuntu bug report for 2.6.20 about a NULL pointer
dereference unless 'delay_use' is 8 or more, for example).

It also looks like some distros have already shipped with delay_use=0,
so the five second default may well be totally historical.

In other words: "Let's see if anybody screams".
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      a4a47bc0
  3. 25 Feb, 2010 12 commits
  5. 24 Feb, 2010 18 commits
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