Normally _regulator_do_enable() isn't called on an already-enabled
rdev.  That's because the main caller, _regulator_enable() always
calls _regulator_is_enabled() and only calls _regulator_do_enable() if
the rdev was not already enabled.

However, there is one caller of _regulator_do_enable() that doesn't
check: regulator_suspend_finish().  While we might want to make
regulator_suspend_finish() behave more like _regulator_enable(), it's
probably also a good idea to make _regulator_do_enable() robust if it
is called on an already enabled rdev.

At the moment, _regulator_do_enable() is _not_ robust for already
enabled rdevs if we're using an ena_pin.  Each time
_regulator_do_enable() is called for an rdev using an ena_pin the
reference count of the ena_pin is incremented even if the rdev was
already enabled.  This is not as intended because the ena_pin is for
something else: for keeping track of how many active rdevs there are
sharing the same ena_pin.

Here's how the reference counting works here:

* Each time _regulator_enable() is called we increment
  rdev->use_count, so _regulator_enable() calls need to be balanced
  with _regulator_disable() calls.

* There is no explicit reference counting in _regulator_do_enable()
  which is normally just a warapper around rdev->desc->ops->enable()
  with code for supporting delays.  It's not expected that the
  "ops->enable()" call do reference counting.

* Since regulator_ena_gpio_ctrl() does have reference counting
  (handling the sharing of the pin amongst multiple rdevs), we
  shouldn't call it if the current rdev is already enabled.

Note that as part of this we cleanup (remove) the initting of
ena_gpio_state in regulator_register().  In _regulator_do_enable(),
_regulator_do_disable() and _regulator_is_enabled() is is clear that
ena_gpio_state should be the state of whether this particular rdev has
requested the GPIO be enabled.  regulator_register() was initting it
as the actual state of the pin.

Fixes: 967cfb18c0e3 ("regulator: core: manage enable GPIO list")
Signed-off-by: Doug Anderson <dianders@chromium.org>
Signed-off-by: Mark Brown <broonie@kernel.org>
Cc: stable@vger.kernel.org

The _regulator_do_enable() call ought to be a no-op when called on an
already-enabled regulator.  However, as an optimization
_regulator_enable() doesn't call _regulator_do_enable() on an already
enabled regulator.  That means we never test the case of calling
_regulator_do_enable() during normal usage and there may be hidden
bugs or warnings.  We have seen warnings issued by the tps65090 driver
and bugs when using the GPIO enable pin.

Let's match the same optimization that _regulator_enable() in
regulator_suspend_finish().  That may speed up suspend/resume and also
avoids exposing hidden bugs.

[Use much clearer commit message from Doug Anderson]

Signed-off-by: Javier Martinez Canillas <javier.martinez@collabora.co.uk>
Signed-off-by: Mark Brown <broonie@kernel.org>
Cc: stable@vger.kernel.org

The commit [39f802d6b6d9: 'regulator: Build sysfs entries with static
attribute groups'] converted the sysfs entry creation to static
attribute groups, but this resulted in a regression due to the NULL
check of rdev->constraints.  At the point where the device is
registered, rdev->constraints isn't set, so the attributes depending
on it are missing.

We may fix it by shuffling the code order in regulator_register(), but
a quicker fix is to just remove this NULL check.  rdev->constraints is
in anyway always set to non-NULL in set_machine_constraints(), thus
the check there is basically superfluous.

Fixes: 39f802d6b6d9 ('regulator: Build sysfs entries with static attribute groups')
Signed-off-by: Takashi Iwai <tiwai@suse.de>
Reportded-by: Steve Twiss <stwiss.opensource@diasemi.com>
Tested-by: Steve Twiss <stwiss.opensource@diasemi.com>
Signed-off-by: Mark Brown <broonie@kernel.org>

Instead of calling device_create_file() manually after the device
registration, put all in attribute groups and filter the unwanted ones
via is_visible callback.  This not only simplifies the code but also
avoids the possible race between the device registration and sysfs
registration.

Signed-off-by: Takashi Iwai <tiwai@suse.de>
Signed-off-by: Mark Brown <broonie@kernel.org>

Refactor drms_uA_update() slightly to allow regulator_set_optimum_mode()
to utilize the same logic instead of duplicating it.

Signed-off-by: Bjorn Andersson <bjorn.andersson@sonymobile.com>
Signed-off-by: Mark Brown <broonie@kernel.org>

Update documentation for regulator_register() function after renaming
its argument.

Signed-off-by: Krzysztof Kozlowski <k.kozlowski@samsung.com>
Reported-by: kbuild test robot <fengguang.wu@intel.com>
Signed-off-by: Mark Brown <broonie@kernel.org>