ACPI / video: Filter the _BCL table for duplicate brightness values

Some devices have duplicate entries in there brightness levels table, ie
on my Dell Latitude E6430 the table looks like this:

[    3.686060] acpi backlight index   0, val 80
[    3.686095] acpi backlight index   1, val 50
[    3.686122] acpi backlight index   2, val 5
[    3.686147] acpi backlight index   3, val 5
[    3.686172] acpi backlight index   4, val 5
[    3.686197] acpi backlight index   5, val 5
[    3.686223] acpi backlight index   6, val 5
[    3.686248] acpi backlight index   7, val 5
[    3.686273] acpi backlight index   8, val 6
[    3.686332] acpi backlight index   9, val 7
[    3.686356] acpi backlight index  10, val 8
[    3.686380] acpi backlight index  11, val 9
etc.

Notice that brightness values 0-5 are all mapped to 5. This means that
if userspace writes any value between 0 and 5 to the brightness sysfs attribute
and then reads it, it will always return 0, which is somewhat unexpected.

This is a problem for ie gnome-settings-daemon, which uses read-modify-write
logic when the users presses the brightness up or down keys. This is done
this way to take brightness changes from other sources into account.

On this specific laptop what happens once the brightness has been set to 0,
is that gsd reads 0, adds 5, writes 5, and on the next brightness up key press
again reads 0, so things get stuck at the lowest brightness setting.

Filtering out the duplicate table entries, makes any write to brightness
read back as the written value as one would expect, fixing this.

Signed-off-by: Hans de Goede <hdegoede@redhat.com>
Reviewed-by: Aaron Lu <aaron.lu@intel.com>
Cc: All applicable <stable@vger.kernel.org>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
ACPI / hotplug / PCI: Rename register_slot() to acpiphp_add_context()

The name of register_slot() doesn't really reflect what the function
is does, so rename it to acpiphp_add_context() and add a proper
kerneldoc comment to it.

Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
ACPI / hotplug / PCI: Add ACPIPHP contexts to devices handled by PCIeHP

Currently, ACPIPHP does not add hotplug context to devices that
should be handled by the native PCI hotplug (PCIeHP) code.  The
reason why was because PCIeHP didn't know about the devices'
connections with ACPI and would not clean up things properly
during an eject of an ACPI-backed device, for example.

However, after recent changes that made the ACPI core create struct
acpi_device objects for all namespace nodes regardless of the
underlying devices' status and added PCI rescan-remove locking to
both ACPIPHP and PCIeHP, that concern is not valid any more.
Namely, after those changes PCIeHP need not care about the ACPI
side of things any more and it should be serialized with respect to
ACPIPHP and they won't be running concurrently with each other in
any case.

For this reason, make ACPIPHP to add its hotplug context to
all devices with ACPI companions, even the ones that should be
handled by PCIeHP in principle.  That may work around hotplug
issues on some systems where PCIeHP is supposed to work, but it
doesn't and the ACPI hotplug signaling works instead.

Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Merge back earlier 'acpi-dock' material.
ACPI / dock: Dispatch dock notifications from the global notify handler

The ACPI dock station code carries out an extra namespace scan
before the main one in order to find and register all of the dock
device objects.  Then, it registers a notify handler for each of
them for handling dock events.

However, dock device objects need not be scanned for upfront.  They
very well can be enumerated and registered during the first phase
of the main namespace scan, before attaching scan handlers and ACPI
drivers to ACPI device objects.  Then, the dependent devices can be
added to the in the second phase.  That makes it possible to drop
the extra namespace scan, so do it.

Moreover, it is not necessary to register notify handlers for all
of the dock stations' namespace nodes, becuase notifications may
be dispatched from the global notify handler for them.  Do that and
drop two functions used for dock notify handling, acpi_dock_deferred_cb()
and dock_notify_handler(), that aren't necessary any more.

Finally, some dock station objects have _HID objects matching the
ACPI container scan handler which causes it to claim those objects
and try to handle their hotplug, but that is not a good idea,
because those objects have their own special hotplug handling anyway.
For this reason, the hotplug_notify flag should not be set for ACPI
device objects representing dock stations and the container scan
handler should be made ignore those objects, so make that happen.

Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
ACPI / dock: Pass ACPI device pointer to acpi_device_is_battery()

Since we already know what the device's PNP IDs are when
acpi_device_is_battery() is called, it is not necessary to run
acpi_get_object_info() for the device in that function.  Instead, if
acpi_device_is_battery() is passed a pointer to a struct acpi_device
object, it can use the list of PNP IDs from that object, so make that
happen and modify the function's header accordingly

Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
ACPI / dock: Associate dock platform devices with ACPI device objects

To allow user space to check which ACPI device object the dock
station is represented by, make acpi_dock_add() indicate to
platform_device_register_full() which ACPI device object should
be the companion of the new platform device.

This also ensures that the ACPI device object in question will
not go away while the dock platform device is present (which is
always).

Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Merge branch 'acpi-video'

* acpi-video:
  ACPI / video: Filter the _BCL table for duplicate brightness values
Merge branch 'acpi-pci-hotplug-next' into linux-next

* acpi-pci-hotplug-next:
  ACPI / hotplug / PCI: Add ACPIPHP contexts to devices handled by PCIeHP
  ACPI / hotplug / PCI: Rename register_slot() to acpiphp_add_context()
Merge branch 'acpi-dock-next' into linux-next

* acpi-dock-next:
  ACPI / dock: Associate dock platform devices with ACPI device objects
  ACPI / dock: Pass ACPI device pointer to acpi_device_is_battery()
  ACPI / dock: Dispatch dock notifications from the global notify handler