... let's see whether this catches anything earlier and I can track
down a few bugs.

v2: Add more checks and also add DRM_DEBUG_KMS output so that it's
clear which connector/encoder/crtc is being checked atm. Which proved
rather useful for debugging ...

v3: Add a WARN in the common encoder dpms function, now that also
modeset changes properly update the dpms state ...

v4: Properly add a short explanation for each WARN, to avoid the need
to correlate dmesg lines with source lines accurately. Suggested by
Chris Wilson.

v5: Also dump (expected, found) for state checks (or wherever it's not
apparent from the test what exactly mismatches with expectations).
Again suggested by Chris Wilson.

v6: Due to an issue reported by Paulo Zanoni I've noticed that the
encoder checking is by far not as strict as it could and should be.
Improve this.
Reviewed-by: NJesse Barnes <jbarnes@virtuousgeek.org>
Signed-Off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>

We need this to avoid confusing the hw state readout code with the cpt
pch plls at resume time: We'd read the new pipe state (which is
disabled), but still believe that we have a life pll connected to that
pipe (from before the suspend). Hence properly disable pipes to clear
out all the residual state.

This has the neat side-effect that we don't enable ports prematurely
by restoring bogus state from the saved register values.
Reviewed-by: NJesse Barnes <jbarnes@virtuousgeek.org>
Signed-Off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>

With this change we can (finally!) rip out a few of the temporary hacks
and clean up a few other things:
- Kill intel_crtc_prepare_encoders, now unused.
- Kill the hacks in the crtc_disable/enable functions to always call the
  encoder callbacks, we now always call the crtc functions with the right
  encoder -> crtc links.
- Also push down the crtc->enable, encoder and connector dpms state
  updates. Unfortunately we can't add a WARN in the crtc_disable
  callbacks to ensure that the crtc is always still enabled when
  disabling an output pipe - the crtc sanitizer of the hw readout path
  can hit this when it needs to disable an active pipe without any
  enabled outputs.
- Only call crtc->disable if the pipe is already enabled - again avoids
  running afoul of the new WARN.

v2: Copy&paste our own version of crtc_in_use, too.

v3: We need to update the dpms an encoder->connectors_active states,
too.

v4: I've forgotten to kill the unconditional encoder->disable calls in
the crtc_disable functions.

v5: Rip out leftover debug printk.

v6: Properly clear intel_encoder->connectors_active. This wasn't
properly cleared when disabling an encoder because it was no longer on
the new connector list, but the crtc was still enabled (i.e. switching
the encoder of an active crtc). Reported by Jani Nikula.

v7: Don't clobber the encoder->connectors_active state of untouched
encoders. Since X likes to first disable all outputs with dpms off
before setting a new framebuffer, this hit a few warnings. Reported by
Paulo Zanoni.

v8: Kill the now stale comment warning that intel_crtc->active is not
always updated at the right times.
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>

Now that set_mode also disables crtcs and expects it's new
configuration in the staged output links we need to adjust the load
detect code a bit.
Reviewed-by: NJesse Barnes <jbarnes@virtuousgeek.org>
Signed-Off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>

This seems to be the symptom of a few neat bugs, hence be more
obnoxious when this fails.
Reviewed-by: NJesse Barnes <jbarnes@virtuousgeek.org>
Signed-Off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>

Because that's what it is. Unfortunately we can't rip this out because
the fb helper has an incetious relationship with the crtc helper - it
likes to call disable_unused_functions, among other things.
Reviewed-by: NJesse Barnes <jbarnes@virtuousgeek.org>
Signed-Off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>

This requires a few changes
- We still need a noop function for crtc->disable, becuase the fb
  helper is a bit too intimate with the crtc helper.
- We need to clear crtc->fb ourselves in intel_crtc_disable now that
  we no longer rely on the helper's disable_unused_functions to do
  that.
- We need to split out the sare update code, becuase the crtc code
  can't call update_dpms any more, it needs to disable the crtc
  unconditionally. This is because we now keep onto the encoder ->
  crtc mapping of the (still) active output pipe configuration.
- To check that we really disable a crtc that still has encoders,
  insert a WARN_ON(!enabled) in the crtc disable function.
- Lastly, we need to walk over all crtcs to update their enabled state
  after having called commit_output_state - for all disabled crtcs the
  crtc helper code has done that for us previously.

v2: Update connector dpms and encoder->connectors_active after
disabling the crtc, too.

v3: Noop-out intel_encoder_disable. Similarly to the crtc disable
callback used by the crtc helper code we can't simply remove all these
encoder callbacks: The fb helper (which we still use) has a rather
incetious relationship with the crtc helper code ...
Reviewed-by: NJesse Barnes <jbarnes@virtuousgeek.org>
Signed-Off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>

... using the pipe masks from the previous patch.

Well, not quite:
- We still need to call the disable_unused_functions helper, until
  we've moved the call to commit_output_state further down and
  adjusted intel_crtc_disable a bit. The next patch will do that.
- Because we don't support (yet) mode changes on more than one crtc at
  a time, some of the modeset_pipes checks are a bit hackish - but
  that only needs fixing once we incorporate global modeset support.
Reviewed-by: NJesse Barnes <jbarnes@virtuousgeek.org>
Signed-Off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>

This is definetely a bit more generic than currently required, but if
we keep track of all crtcs that need to be disabled/enable (because
they loose an encoder or something similar), crtcs that get completely
disabled and those that we need to do an actual mode change nicely
prepares us for global modeset operations on multiple crtcs.

The only big thing missing here would be a global resource allocation
step (for e.g. pch plls), which would equally frob these bitmasks if
e.g. a crtc only needs a new pll. Or if we need to enable dithering on
an another pipe due to bandwidth constrains somewhere.

These masks aren't yet put to use in this patch, this will follow in the
next one.

v2-v5: Fix up the computations for good (hopefully).

v6: Fixup a confusion reported by Damien Lespiau: I've conserved the
(imo braindead) behaviour of the crtc helper to disable _any_
disconnected outputs if we do a modeset, even when that newly disabled
connector isn't connected to the crtc being changed by the modeset.

The effect of that is that we could disable an arbitrary number of
unrelated crtcs, which I haven't taken into account when writing this
code. Fix this up.
Reviewed-by: NJesse Barnes <jbarnes@virtuousgeek.org>
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>

The "is this encoder cloned" check will be reused by the lvds encoder,
hence exract it.

v2: Be a bit more careful about that we need to check the new, staged
ouput configuration in the check_non_cloned helper ...

v3: Kill the double negation with s/!non_cloned/is_cloned/, suggested
by Jesse Barnes.
Reviewed-by: NJesse Barnes <jbarnes@virtuousgeek.org>
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>

While at it, adjust a few things:
- Only assigng the new mode to crtc->mode right before calling the
  mode_set callbacks - none of the previous callbacks depend upon
  this, they all use the mode argument (as they should).
- Check encoder->new_crtc instead of the current crtc to check whether
  the encoder will be used. This prepares for moving the staged output
  committing further down in the sequence. Follow-on patches will fix
  up individual ->mode_fixup callbacks (only tv and lvds are affected
  though).
Reviewed-by: NJesse Barnes <jbarnes@virtuousgeek.org>
Signed-Off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>

It's rather pointless to compute crtc->enabled twice right away ;-)

The only thing we really have to be careful about is that we frob the
dpms state only after a successful modeset and when we've actually
haven't just disabled the crtc.

Hooray for convoluted interfaces ...
Reviewed-by: NJesse Barnes <jbarnes@virtuousgeek.org>
Signed-Off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>

Originally this has been introduced in

commit 6eebd6bb
Author: Chris Wilson <chris@chris-wilson.co.uk>
Date:   Mon Nov 28 21:10:05 2011 +0000

    drm: Fix lack of CRTC disable for drm_crtc_helper_set_config(.fb=NULL)

With the improvements of the output state staging and no longer
overwriting crtc->fb before the hw state is updated we can now handle
crtc disabling as part of the normal modeset sequence.
Reviewed-by: NJesse Barnes <jbarnes@virtuousgeek.org>
Signed-Off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>

Passing in the old fb, having overwritten the current fb, leads to
some neatly convoluted code. It's much simpler if we defer the
crtc->fb update to the place that updates the hw, in pipe_set_base.
This way we also don't need to restore anything in case something
fails - we only update crtc->fb once things have succeeded.

The real reason for this change is that now we keep the old fb
assigned to crtc->fb, which allows us to finally move the crtc disable
case into the common low-level set_mode function in the next patch.

Also don't clobber crtc->x and crtc->y, we neatly pass these down the
callchain already. Unfortunately we can't do the same with crtc->mode,
because that one is being used in the mode_set callbacks.

v2: Don't restore the drm_crtc object any more on failed modesets,
since we've lose an fb reference otherwise. Also (and this is the
reason this has been found), this totally confused the modeset state
tracking, since it clobbers crtc->enabled. Issue reported by Paulo
Zanoni.

v3: Rip out the entire crtc saving into struct intel_set_config, not
just the restoring part.
Reviewed-by: NJesse Barnes <jbarnes@virtuousgeek.org>
Signed-Off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>

This is the core of the new modeset logic.

The current code which is based upon the crtc helper code first
updates all the link of the new display pipeline and then calls the
lower-level set_mode function to execute the required callbacks to get
there. The issue with this approach is that for disabling we need to
know the _current_ display pipe state, not the new one.

Hence we need to stage the new state of the display pipe and only
update it once we have disabled the current configuration and before we
start to update the hw registers with the new configuration.

This patch here just prepares the ground by switching the new output
state computation to these staging pointers. To make it clearer,
rename the old update_output_state function to stage_output_state.

A few peculiarities:
- We're also calling the set_mode function at various places to update
  properties. Hence after a successfule modeset we need to stage the
  current configuration (for otherwise we might fall back again). This
  happens automatically because as part of the (successful) modeset we
  need to copy the staged state to the real one. But for the hw
  readout code we need to make sure that this happens, too.
- Teach the new staged output state computation code the required
  smarts to handle the disabling of outputs. The current code handles
  this in a special case, but to better handle global modeset changes
  covering more than one crtc, we want to do this all in the same
  low-level modeset code.
- The actual modeset code is still a bit ugly and wants to know the new
  crtc->enabled state a bit early. Follow-on patches will clean that
  up, for now we have to apply the staged output configuration early,
  outside of the set_mode functions.
- Improve/add comments in stage_output_state.

Essentially all that is left to do now is move the disabling code into
set_mode and then move the staged state update code also into
set_mode, at the right place between disabling things and calling the
mode_set callbacks for the new configuration.

v2: Disabling a crtc works by passing in a NULL mode or fb, userspace
doesn't hand in the list of connectors. We therefore need to detect
this case manually and tear down all the output links.

v3: Properly update the output staging pointers after having read out
the hw state.

v4: Simplify the code, add more DRM_DEBUG_KMS output and check a few
assumptions with WARN_ON. Essentially all things that I've noticed
while debugging issues in other places of the code.

v4: Correctly disable the old set of connectors when enabling an
already enabled crtc on a new set of crtc. Reported by Paulo Zanoni.
Reviewed-by: NJesse Barnes <jbarnes@virtuousgeek.org>
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>

We actually only touch the connector -> encoder and encoder -> crtc
linking. So it's enough to just save/restore that.

While at it, also switch to kcalloc to allocate these arrays (omission
in the commit message spotted by Jesse Barnes).
Reviewed-by: NJesse Barnes <jbarnes@virtuousgeek.org>
Signed-Off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>

Because they all are, the ioctl command never calls us with any of
these violated. Also drop a equally pointless empty debug message (and
also in set_cursor, while we're at it).

With all these changes, intel_crtc_set_config is neatly condensed down
to it's essence, the actual modeset code (or fb update calling code)

v2: The fb helper code is actually stretching ->set_config semantics a bit,
it calls it with set->mode == NULL but set->fb != NULL.
Reviewed-by: NJesse Barnes <jbarnes@virtuousgeek.org>
Signed-Off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>

Otherwise we'll set_fb complains pretty loudly if we the crtc is off
and userspace moves the NULL fb around a bit. Yeah, this actually
happens in the wild ...
Reviewed-by: NJesse Barnes <jbarnes@virtuousgeek.org>
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>

Yikes!

But yeah, we have to do this until someone volunteers to clean up the
fb helper and rid it of its incetious relationship with the crtc
helper code.
Reviewed-by: NJesse Barnes <jbarnes@virtuousgeek.org>
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>

Note that this function already clobbers the mode config state,
so we have to clean things up if something fails.
Reviewed-by: NJesse Barnes <jbarnes@virtuousgeek.org>
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>

This computes what exactly changed in the modeset configuration, i.e.
whether a full modeset is required or only an update of the
framebuffer base address or no change at all.

In the future we might add more checks for e.g. when only the output
mode changed, so that we could do a minimal modeset for outputs that
support this. Like the lvds/eDP panels where we only need to update
the panel fitter.
Reviewed-by: NJesse Barnes <jbarnes@virtuousgeek.org>
Signed-Off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>

At the end this won't be of much use to us, but meanwhile just extract
it to get a better overview of what exactly set_config does.
Reviewed-by: NJesse Barnes <jbarnes@virtuousgeek.org>
Signed-Off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>

intel_crtc_set_config is an unwidly beast and is in serious need of
some function extraction. To facilitate that, introduce a struct to
keep track of all the state involved. Atm it doesn't do much more than
keep track of all the allocated memory.

v2: Apply some bikeshed to intel_set_config_free, as suggested by
Jesse Barnes.
Reviewed-by: NJesse Barnes <jbarnes@virtuousgeek.org>
Signed-Off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>

Many BIOSen forget to turn on the pipe A after resume (because they
actually don't turn on anything), so we have to do that ourselves when
sanitizing the hw state.

I've discovered this due to the recent addition of a pipe WARN that
takes the force quirk into account.

v2: Actually try to enable the pipe with a proper configuration instead
of simpyl switching it on with whatever random state the bios left it
in after resume.

v3: Fixup rebase conflict - the load_detect functions have lost their
encoder argument.
Reviewed-by: NJesse Barnes <jbarnes@virtuousgeek.org>
Signed-Off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>

Afaict this has been used for two things:
- To prevent the crtc enable code from being run twice. We have now
  intel_crtc->active to track this in a more precise way.
- To ensure the code copes correctly with the unknown hw state after
  boot and resume. Thanks to the hw state readout and sanitize code we
  have now a better way to handle this.

The only thing it still does is complicate our modeset state space.

Having outlived its usefullness, let it just die.
Reviewed-by: NJesse Barnes <jbarnes@virtuousgeek.org>
Signed-Off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>

Atm we can only check the connector state after a dpms call - while
doing modeset with the copy&pasted crtc helper code things are too
ill-defined for proper checking. But the idea is very much to call
this check from the modeset code, too.

v2: Fix dpms check and don't presume that if the hw isn't on that it
must not be linked up with an encoder (it could simply be switched off
with the dpms state).
Reviewed-by: NJesse Barnes <jbarnes@virtuousgeek.org>
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>

... instead of resetting a few things and hoping that this will work
out.

To properly disable the output pipelines at the initial modeset after
resume or boot up we need to have an accurate picture of which outputs
are enabled and connected to which crtcs. Otherwise we risk disabling
things at the wrong time, which can lead to hangs (or at least royally
confused panels), both requiring a walk to the reset button to fix.

Hence read out the hw state with the freshly introduce get_hw_state
functions and then sanitize it afterwards.

For a full modeset readout (which would allow us to avoid the initial
modeset at boot up) a few things are still missing:
- Reading out the mode from the pipe, especially the dotclock
  computation is quite some fun.
- Reading out the parameters for the stolen memory framebuffer and
  wrapping it up.
- Reading out the pch pll connections - luckily the disable code
  simply bails out if the crtc doesn't have a pch pll attached (even
  for configurations that would need one).

This patch here turned up tons of smelly stuff around resume: We
restore tons of register in seemingly random way (well, not quite, but
we're not too careful either), which leaves the hw in a rather
ill-defined state: E.g. the port registers are sometimes
unconditionally restore (lvds, crt), leaving us with an active
encoder/connector but no active pipe connected to it. Luckily the hw
state sanitizer detects this madness and fixes things up a bit.

v2: When checking whether an encoder with active connectors has a crtc
wire up to it, check for both the crtc _and_ it's active state.

v3:
- Extract intel_sanitize_encoder.
- Manually disable active encoders without an active pipe.

v4: Correclty fix up the pipe<->plane mapping on machines where we
switch pipes/planes. Noticed by Chris Wilson, who also provided the
fixup.

v5: Spelling fix in a comment, noticed by Paulo Zanoni
Reviewed-by: NJesse Barnes <jbarnes@virtuousgeek.org>
Signed-Off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>

It is all glorious if we try really hard to only enable/disable an
entire display pipe to ensure that everyting happens in the right
order. But if we don't know the output configuration when the driver
takes over, this will all be for vain because we'll make the hw angry
right on the first modeset - we don't know what outputs/ports are
enabled and hence have to disable everything in a rather ad-hoc way.

Hence we need to be able to read out the current hw state, so that we
can properly tear down the current hw state on the first modeset.
Obviously this is also a nice preparation for the fastboot work, where
we try to avoid the modeset on driver load if it matches what the hw
is currently using.

Furthermore we'll be using these functions to cross-check the actual
hw state with what we think it should be, to ensure that the modeset
state machine actually works as advertised.

This patch only contains the interface definitions and a little helper
for the simple case where we have a 1:1 encoder to connector mapping.
Reviewed-by: NJesse Barnes <jbarnes@virtuousgeek.org>
Signed-Off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>

This is the first tiny step towards cross-checking the entire modeset
state machine with WARNs. A crtc can only be enabled when it's
actually in use, i.e. crtc->active imlies crtc->enabled.

Unfortunately we can't (yet) check this when disabling the crtc,
because the crtc helpers are a bit slopy with updating state and
unconditionally update crtc->enabled before changing the hw state.

Fixing that requires quite some more work.
Reviewed-by: NJesse Barnes <jbarnes@virtuousgeek.org>
Signed-Off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>

Instead of going through the crtc helper function tables.
Reviewed-by: NJesse Barnes <jbarnes@virtuousgeek.org>
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>

With the new infrastructure we're doing this when enabling/disabling
the entire display pipe.
Reviewed-by: NJesse Barnes <jbarnes@virtuousgeek.org>
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>

- We don't have the ->get_crtc callback.
- Call intel_encoder->disable directly.
Reviewed-by: NJesse Barnes <jbarnes@virtuousgeek.org>
Signed-Off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>

Together with the static helper functions drm_crtc_prepare_encoders
and drm_encoder_disable (which will be simplified in the next patch,
but for now are 1:1 copies). Again, no changes beside new names for
these functions.

Also call our new set_mode instead of the crtc helper one now in all
the places we've done so far.

v2: Call the function just intel_set_mode to better differentia it
from intel_crtc_mode_set which really only does the ->mode_set step of
the entire modeset sequence on one crtc. Whereas this function does
the global change.
Acked-by: NJesse Barnes <jbarnes@virtuousgeek.org>
Signed-Off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>

Also kill the error-path, we have a fixed connector->encoder mapping.

Unfortunately we can't rip out all the ->best_encoder callbacks, these
are all still used by the fb_helper. Neat helper layering violation there.
Reviewed-by: NJesse Barnes <jbarnes@virtuousgeek.org>
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>

And drop the check, we always have it.
Reviewed-by: NJesse Barnes <jbarnes@virtuousgeek.org>
Signed-Off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>

And the following static functions required by it:
drm_encoder_crtc_ok, drm_crtc_helper_disable

No changes safe for the s/drm/intel prefix change.
Acked-by: NJesse Barnes <jbarnes@virtuousgeek.org>
Signed-Off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>

We no longer need them. And now that all encoders are converted, we
can finally move the cpt modeset check to the right place - at the end
of the crtc_enable function.
Reviewed-by: NJesse Barnes <jbarnes@virtuousgeek.org>
Signed-Off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>

All encoders are now converted so there's no need for these checks any
more.
Reviewed-by: NJesse Barnes <jbarnes@virtuousgeek.org>
Signed-Off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>

Yeah, big patch but I couldn't come up with a neat idea of how to
split it up further, that wouldn't break dpms on cloned configs
somehow. But the changes in dvo/sdvo/crt are all pretty much
orthonogal, so it's not too bad a patch.

These are the only encoders that support cloning, which requires a few
special changes compared to the previous patches.
- Compute the desired state of the display pipe by walking all
  connected encoders and checking whether any has active connectors.
  To make this clearer, drop the old mode parameter to the crtc dpms
  function and rename it to intel_crtc_update_dpms.
- There's the curious case of intel_crtc->dpms_mode. With the previous
  patches to remove the overlay pipe A code and to rework the load
  detect pipe code, the big users are gone. We still keep it to avoid
  enabling the pipe twice, but we duplicate this logic with
  crtc->active, too. Still, leave this for now and just push a fake
  dpms mode into it that reflects the state of the display pipe.

Changes in the encoder dpms functions:
- We clamp the dpms state to the supported range right away. This is
  escpecially important for the VGA outputs, where only older hw
  supports the intermediate states. This (and the crt->adpa_reg patch)
  allows us to unify the crt dpms code again between all variants
  (gmch, vlv and pch).
- We only enable/disable the output for dvo/sdvo and leave the encoder
  running. The encoder will be disabled/enabled when we switch the
  state of the entire output pipeline (which will happen right away
  for non-cloned setups). This way the duplication is reduced and
  strange interaction when disabling output ports at the wrong time
  avoided.

The dpms code for all three types of connectors contains a bit of
duplicated logic, but I think keeping these special cases separate is
simpler: CRT is the only one that hanldes intermediate dpms state
(which requires extra logic to enable/disable things in the right
order), and introducing some abstraction just to share the code
between dvo and sdvo smells like overkill. We can do that once someone
bothers to implement cloning for the more modern outputs. But I doubt
that this will ever happen.

v2: s/crtc/crt/_set_dpms, noticed by Paulo Zanoni.
Reviewed-by: NJesse Barnes <jbarnes@virtuousgeek.org>
Signed-Off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>

I've picked hdmi as the first encoder to convert because it's rather
simple:
- no cloning possible
- no differences between prepare/commit and dpms off/on switching.

A few changes are required to do so:
- Split up the dpms code into an enable/disable function and wire it
  up with the intel encoder.
- Noop out the existing encoder prepare/commit functions used by the
  crtc helper - our crtc enable/disable code now calls back into the
  encoder enable/disable code at the right spot.
- Create new helper functions to handle dpms changes.
- Add intel_encoder->connectors_active to better track dpms state. Atm
  this is unused, but it will be useful to correctly disable the
  entire display pipe for cloned configurations. Also note that for
  now this is only useful in the dpms code - thanks to the crtc
  helper's dpms confusion across a modeset operation we can't (yet)
  rely on this having a sensible value in all circumstances.
- Rip out the encoder helper dpms callback, if this is still getting
  called somewhere we have a bug. The slight issue with that is that
  the crtc helper abuses dpms off to disable unused functions. Hence
  we also need to implement a default encoder disable function to do
  just that with the new encoder->disable callback.
- Note that we drop the cpt modeset verification in the commit
  callback, too. The right place to do this would be in the crtc's
  enable function, _after_ all the encoders are set up. But because
  not all encoders are converted yet, we can't do that. Hence disable
  this check temporarily as a minor concession to bisectability.

v2: Squash the dpms mode to only the supported values -
connector->dpms is for internal tracking only, we can hence avoid
needless state-changes a bit whithout causing harm.

v3: Apply bikeshed to disable|enable_ddi, suggested by Paulo Zanoni.
Reviewed-by: NJesse Barnes <jbarnes@virtuousgeek.org>
Signed-Off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>