cpufreq: tegra: don't error target() when suspended

d4019f0a92ab "cpufreq: move freq change notifications to cpufreq core"
added code to the cpufreq core to print an error if a cpufreq driver's
.target() function returned an error. This exposed the fact that Tegra's
cpufreq driver returns an error when it is ignoring requests due to the
system being suspended.

Modify Tegra's .target() function not to return an error in this case;
this prevents the error prints. The argument is that since the suspend
hook can't and doesn't inform the cpufreq core when its requests will
be ignored, there's no way for the cpufreq core to squelch them, so it's
not an error for the requests to keep coming. This change make the Tegra
driver consistent with how the Exynos handles the same situation. Note
that s5pv210-cpufreq.c probably suffers from this same issue though.

Fixes: d4019f0a92ab (cpufreq: move freq change notifications to cpufreq core)
Signed-off-by: Stephen Warren <swarren@nvidia.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
cpufreq: exynos: Remove unwanted EXPORT_SYMBOL

The init functions are linked statically (no support for
dynamic loading) and have no other users. Hence remove
EXPORT_SYMBOL for these functions.

Signed-off-by: Sachin Kamat <sachin.kamat@linaro.org>
Acked-by: Viresh Kumar <viresh.kumar@linaro.org>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
cpufreq: suspend governors on system suspend/hibernate

This patch adds cpufreq suspend/resume calls to dpm_{suspend|resume}_noirq()
for handling suspend/resume of cpufreq governors.

Lan Tianyu (Intel) & Jinhyuk Choi (Broadcom) found anr issue where
tunables configuration for clusters/sockets with non-boot CPUs was
getting lost after suspend/resume, as we were notifying governors
with CPUFREQ_GOV_POLICY_EXIT on removal of the last cpu for that
policy and so deallocating memory for tunables. This is fixed by
this patch as we don't allow any operation on governors after
device suspend and before device resume now.

Reported-and-tested-by: Lan Tianyu <tianyu.lan@intel.com>
Reported-by: Jinhyuk Choi <jinchoi@broadcom.com>
Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>
[rjw: Changelog, minor cleanups]
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
cpufreq: fix garbage kobjects on errors during suspend/resume

This is effectively a revert of commit 5302c3fb2e62 ("cpufreq: Perform
light-weight init/teardown during suspend/resume"), which enabled
suspend/resume optimizations leaving the sysfs files in place.

Errors during suspend/resume are not handled properly, leaving
dead sysfs attributes in case of failures.  There are are number of
functions with special code for the "frozen" case, and all these
need to also have special error handling.

The problem is easy to demonstrate by making cpufreq_driver->init()
or cpufreq_driver->get() fail during resume.

The code is too complex for a simple fix, with split code paths
in multiple blocks within a number of functions.  It is therefore
best to revert the patch enabling this code until the error handling
is in place.

Examples of problems resulting from resume errors:

WARNING: CPU: 0 PID: 6055 at fs/sysfs/file.c:343 sysfs_open_file+0x77/0x212()
missing sysfs attribute operations for kobject: (null)
Modules linked in: [stripped as irrelevant]
CPU: 0 PID: 6055 Comm: grep Tainted: G      D      3.13.0-rc2 #153
Hardware name: LENOVO 2776LEG/2776LEG, BIOS 6EET55WW (3.15 ) 12/19/2011
 0000000000000009 ffff8802327ebb78 ffffffff81380b0e 0000000000000006
 ffff8802327ebbc8 ffff8802327ebbb8 ffffffff81038635 0000000000000000
 ffffffff811823c7 ffff88021a19e688 ffff88021a19e688 ffff8802302f9310
Call Trace:
 [<ffffffff81380b0e>] dump_stack+0x55/0x76
 [<ffffffff81038635>] warn_slowpath_common+0x7c/0x96
 [<ffffffff811823c7>] ? sysfs_open_file+0x77/0x212
 [<ffffffff810386e3>] warn_slowpath_fmt+0x41/0x43
 [<ffffffff81182dec>] ? sysfs_get_active+0x6b/0x82
 [<ffffffff81182382>] ? sysfs_open_file+0x32/0x212
 [<ffffffff811823c7>] sysfs_open_file+0x77/0x212
 [<ffffffff81182350>] ? sysfs_schedule_callback+0x1ac/0x1ac
 [<ffffffff81122562>] do_dentry_open+0x17c/0x257
 [<ffffffff8112267e>] finish_open+0x41/0x4f
 [<ffffffff81130225>] do_last+0x80c/0x9ba
 [<ffffffff8112dbbd>] ? inode_permission+0x40/0x42
 [<ffffffff81130606>] path_openat+0x233/0x4a1
 [<ffffffff81130b7e>] do_filp_open+0x35/0x85
 [<ffffffff8113b787>] ? __alloc_fd+0x172/0x184
 [<ffffffff811232ea>] do_sys_open+0x6b/0xfa
 [<ffffffff811233a7>] SyS_openat+0xf/0x11
 [<ffffffff8138c812>] system_call_fastpath+0x16/0x1b

The failure to restore cpufreq devices on cancelled hibernation is
not a new bug. It is caused by the ACPI _PPC call failing unless the
hibernate is completed. This makes the acpi_cpufreq driver fail its
init.

Previously, the cpufreq device could be restored by offlining the
cpu temporarily.  And as a complete hibernation cycle would do this,
it would be automatically restored most of the time.  But after
commit 5302c3fb2e62 the leftover sysfs attributes will block any
device add action.  Therefore offlining and onlining CPU 1 will no
longer restore the cpufreq object, and a complete suspend/resume
cycle will replace it with garbage.

Fixes: 5302c3fb2e62 ("cpufreq: Perform light-weight init/teardown during suspend/resume")
Cc: 3.12+ <stable@vger.kernel.org> # 3.12+
Signed-off-by: Bjørn Mork <bjorn@mork.no>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>