ACPI / video: Change the default for video.use_native_backlight to 1

Now that we're hoping to have resolved all of the problems with
video.use_native_backlight=1, make that the default at last.

Link: http://marc.info/?l=linux-acpi&m=139716088401106&w=2
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Merge branch 'acpi-video' into bleeding-edge

* acpi-video:
  ACPI / video: Change the default for video.use_native_backlight to 1
cpufreq: add support for intermediate (stable) frequencies

Douglas Anderson, recently pointed out an interesting problem due to which
udelay() was expiring earlier than it should.

While transitioning between frequencies few platforms may temporarily switch to
a stable frequency, waiting for the main PLL to stabilize.

For example: When we transition between very low frequencies on exynos, like
between 200MHz and 300MHz, we may temporarily switch to a PLL running at 800MHz.
No CPUFREQ notification is sent for that. That means there's a period of time
when we're running at 800MHz but loops_per_jiffy is calibrated at between 200MHz
and 300MHz. And so udelay behaves badly.

To get this fixed in a generic way, introduce another set of callbacks
get_intermediate() and target_intermediate(), only for drivers with
target_index() and CPUFREQ_ASYNC_NOTIFICATION unset.

get_intermediate() should return a stable intermediate frequency platform wants
to switch to, and target_intermediate() should set CPU to that frequency,
before jumping to the frequency corresponding to 'index'. Core will take care of
sending notifications and driver doesn't have to handle them in
target_intermediate() or target_index().

NOTE: ->target_index() should restore to policy->restore_freq in case of
failures as core would send notifications for that.

Tested-by: Stephen Warren <swarren@nvidia.com>
Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>
Reviewed-by: Doug Anderson <dianders@chromium.org>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
cpufreq: Tegra: implement intermediate frequency callbacks

Tegra has been switching to intermediate frequency (pll_p_clk) forever.
CPUFreq core has better support for handling notifications for these
frequencies and so we can adapt Tegra's driver to it.

Also do a WARN() if clk_set_parent() fails while moving back to pll_x
as we should have atleast restored to earlier frequency on error.

Tested-by: Stephen Warren <swarren@nvidia.com>
Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>
Reviewed-by: Doug Anderson <dianders@chromium.org>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Revert "cpufreq: Enable big.LITTLE cpufreq driver on arm64"

This reverts commit 4920ab84979d (cpufreq: Enable big.LITTLE cpufreq
driver on arm64) that breaks build on arm64.

Fixes: 4920ab84979d (cpufreq: Enable big.LITTLE cpufreq driver on arm64)
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Merge branch 'pm-cpufreq' into bleeding-edge

* pm-cpufreq:
  Revert "cpufreq: Enable big.LITTLE cpufreq driver on arm64"
  cpufreq: Tegra: implement intermediate frequency callbacks
  cpufreq: add support for intermediate (stable) frequencies