On muxed systems, the other vgaswitcheroo client may depend on i915 to
handle the backlight. We began switching off the backlight since

commit a261b246
Author: Daniel Vetter <daniel.vetter@ffwll.ch>
Date:   Thu Jul 26 19:21:47 2012 +0200

    drm/i915: disable all crtcs at suspend time

breaking backlight on discreet graphics in (some) muxed systems.

Keep the backlight on when the state is changed through vgaswitcheroo.

Note: The alternative would be to add a quirk table to achieve the same
based on system identifiers, but AFAICS it would asymptotically approach
effectively the same as this patch as more IDs are added, but with the
maintenance burden of the quirk table.

Bugzilla: https://bugzilla.kernel.org/show_bug.cgi?id=55311Tested-by: NFede <fedevx@yahoo.com>
Tested-by: NAximab <laurent.debian@gmail.com>
Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=59785Tested-by: Nsfievet <sebastien.fievet@free.fr>
Signed-off-by: NJani Nikula <jani.nikula@intel.com>
Cc: stable@vger.kernel.org
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>

Some card's max brightness level is pretty large, e.g. on Acer Aspire
4732Z, the max level is 989910. If user space set a large enough level
then the current scale done in intel_panel_set_backlight will cause an
integer overflow and the scaled level will be mistakenly small, leaving
user with an almost black screen. This patch fixes this problem.
Signed-off-by: NAaron Lu <aaron.lu@intel.com>
[danvet: Add a comment to explain what's going on.]
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>

BugLink: https://bugzilla.kernel.org/show_bug.cgi?id=47941
BugLink: https://bugs.launchpad.net/bugs/1163720
BugLink: https://bugs.launchpad.net/bugs/1162026

Some machines suffer from non-functional backlight controls if
BLM_PCH_PWM_ENABLE is set, so provide a quirk to avoid doing so.
Apply this quirk to Dell XPS 13 models.
Tested-by: NEric Griffith <EGriffith92@gmail.com>
Tested-by: NKent Baxley <kent.baxley@canonical.com>
Cc: <stable@vger.kernel.org> # v3.8+
Signed-off-by: NKamal Mostafa <kamal@canonical.com>
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>

I.e. for letter/pillarboxing. For those cases we need to adjust the
mode a bit, but Jesse gmch pfit refactoring in

commit 2dd24552
Author: Jesse Barnes <jbarnes@virtuousgeek.org>
Date:   Thu Apr 25 12:55:01 2013 -0700

    drm/i915: factor out GMCH panel fitting code and use for eDP v3

broke that by reordering the computation of the gmch pfit state with
the block of code that prepared the adjusted mode for it and told the
modeset core not to overwrite the adjusted mode with default settings.

We might want to switch around the core code to just fill in defaults,
but this code predates the pipe_config modeset rework. And in the old
crtc helpers we did not have a suitable spot to do this.

Cc: Mika Kuoppala <mika.kuoppala@intel.com>
Cc: Jesse Barnes <jbarnes@virtuousgeek.org>
Cc: Hans de Bruin <jmdebruin@xmsnet.nl>
Reported-and-tested-by: NHans de Bruin <jmdebruin@xmsnet.nl>
Reviewed-by: NJesse Barnes <jbarnes@virtuousgeek.org>
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>

WARN_ON(!spin_is_locked()) is not a good idea on a UP system w/o
spinlock debugging. Use WARN_ON_SMP() instead.

This check has been added in

commit 8ba2d185
Author: Jani Nikula <jani.nikula@intel.com>
Date:   Fri Apr 12 15:18:37 2013 +0300

    drm/i915: protect backlight registers and data with a spinlock
Signed-off-by: NVille Syrjälä <ville.syrjala@linux.intel.com>
Reviewed-by: NJani Nikula <jani.nikula@intel.com>
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>

This was still required a bit (on the cargo-cult side though) when the
state was stored in dev_priv, and when the enable/disable sequence was
botched a bit (to avoid too many updates).

But with pipeconfig we always get a clean slate, so this is pointless.
Rip it out.
Reviewed-by: NMika Kuoppala <mika.kuoppala@intel.com>
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>

pipe_config is the new dev_priv!

More seriously, this is actually better since a pipe_config can be
thrown away if the modeset compute config stage fails. Whereas any
state stored in dev_prive needs to be painstakingly restored, since
otherwise a dpms off/on will wreak massive havoc. Yes, that even
applies to state only used in ->mode_set callbacks, since we need to
call those even for dpms on when the Haswell power well cleared
everything out.
Reviewed-by: NMika Kuoppala <mika.kuoppala@intel.com>
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>

We prevent invalid ones from getting here in the first place, but it
doesn't hurt to have an extra sanity check.
Signed-off-by: NJesse Barnes <jbarnes@virtuousgeek.org>
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>

And put the pfit stuff into substructs while we're at it.
Signed-off-by: NJesse Barnes <jbarnes@virtuousgeek.org>
Reviewed-by: NMika Kuoppala <mika.kuoppala@intel.com>
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>

This gets the panel fitter working on eDP on VLV, and should also apply
to eDP panels on G4x chipsets (if we ever detect and mark an all-in-one
panel as eDP anyway).

A few cleanups are still possible on top of this, for example the LVDS
border control could be placed in the LVDS encoder structure and updated
based on the result of the panel fitter calculation.

Multi-pipe fitting isn't handled correctly either if we ever get a config
that wants to try the panel fitter on more than one output at a time.

v2: use pipe_config for storing pfit values (Daniel)
    add i9xx_pfit_enable function for use by 9xx and VLV (Daniel)
v3: fixup conflicts and lvds_dither check
Reviewed-by: NMika Kuoppala <mika.kuoppala@intel.com>
Signed-off-by: NJesse Barnes <jbarnes@virtuousgeek.org>
[danvet: fix up botched conflict resolution from Jesse:
- border = LVDS_BORDER_ENABLE was lost for CENTER scaling
- comment about gen2/3 panel fitter scaling was lost
- dev_priv->lvds_dither reintroduced.]
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>

v2: Make TRANSCODER_EDP handling more explicit. (Imre)
Signed-off-by: NJani Nikula <jani.nikula@intel.com>
Reviewed-by: NImre Deak <imre.deak@intel.com>
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>

Backlight data and registers are fiddled through LVDS/eDP modeset
enable/disable hooks, backlight sysfs files, asle interrupts, and register
save/restore. Protect the backlight related registers and driver private
fields using a spinlock.

The locking in register save/restore covers a little more than is strictly
necessary, including non-modeset case, for simplicity.

v2: Cover register access, save/restore, i915_read_blc_pwm_ctl() and code
    paths leading there.
Signed-off-by: NJani Nikula <jani.nikula@intel.com>
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>

In preparation of adding locking to backlight, make max backlight value
(the modulation frequency the PWM duty cycle value must not exceed)
internal to intel_panel.c.

Have intel_panel_set_backlight() accept a caller defined range for level,
and scale input to max backlight value internally.

Clean up intel_panel_get_max_backlight() and usage internally.
Signed-off-by: NJani Nikula <jani.nikula@intel.com>
Reviewed-by: NChris Wilson <chris@chris-wilson.co.uk>
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>

Backlight cleanup in the eDP connector destroy callback caused the
backlight device to be removed on some systems that first initialized LVDS
and then attempted to initialize eDP. Prevent multiple backlight
initializations, and ensure backlight cleanup is only done once by moving
it to modeset cleanup.

A small wrinkle is the introduced asymmetry in backlight
setup/cleanup. This could be solved by adding refcounting, but it seems
overkill considering that there should only ever be one backlight device.

Bugzilla: https://bugzilla.kernel.org/show_bug.cgi?id=55701Signed-off-by: NJani Nikula <jani.nikula@intel.com>
Tested-by: NPeter Verthez <peter.verthez@skynet.be>
Cc: stable@vger.kernel.org
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>

No functional changes.
Signed-off-by: NJani Nikula <jani.nikula@intel.com>
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>

The backlight device .get_brightness callback is supposed to return the
actual brightness by querying the hardware, not the cached value. See
Documentation/ABI/stable/sysfs-class-backlight. The callback is there to
support the actual_brightness sysfs file.

With the backlight_level and backlight device brightness now in sync, one
can reliably get the cached value through the brightness sysfs file.
Signed-off-by: NJani Nikula <jani.nikula@intel.com>
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>

A single point of truth would be better than two, but achieving that would
require more abstractions for CONFIG_BACKLIGHT_CLASS_DEVICE=n with not a
whole lot of real benefits. Take the short route and just keep the
backlight levels in sync. In particular, update backlight device brightness
on opregion brightness changes.
Signed-off-by: NJani Nikula <jani.nikula@intel.com>
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>

This reverts commit cf0a6584.

Turns out that cargo-culting breaks systems. Note that we can't revert
further, since

commit 770c1231
Author: Takashi Iwai <tiwai@suse.de>
Date:   Sat Aug 11 08:56:42 2012 +0200

    drm/i915: Fix blank panel at reopening lid

fixed a regression in 3.6-rc kernels for which we've never figured out
the exact root cause. But some further inspection of the backlight
code reveals that it's seriously lacking locking. And especially the
asle backlight update is know to get fired (through some smm magic)
when writing specific backlight control registers. So the possibility
of suffering from races is rather real.

Until those races are fixed I don't think it makes sense to try
further hacks. Which sucks a bit, but sometimes that's how it is :(

References: http://www.mail-archive.com/intel-gfx@lists.freedesktop.org/msg18788.html
Bugzilla: https://bugzilla.kernel.org/show_bug.cgi?id=47941Tested-by: NTakashi Iwai <tiwai@suse.de>
Cc: Jani Nikula <jani.nikula@intel.com>
Cc: Takashi Iwai <tiwai@suse.de>
Cc: stable@vger.kernel.org (the reverted commit was cc: stable, too)
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>

Requested by Daniel.

v2: Fix incorrect num_pipe settings. (Chris)

Cc: Daniel Vetter <daniel.vetter@ffwll.ch>
Signed-off-by: NBen Widawsky <ben@bwidawsk.net>
Reviewed-by: NJesse Barnes <jbarnes@virtuousgeek.org>
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>

770c1231 is the first bad commit
commit 770c1231
Author: Takashi Iwai <tiwai@suse.de>
Date:   Sat Aug 11 08:56:42 2012 +0200

    drm/i915: Fix blank panel at reopening lid

changed the register write sequence for restoring the backlight, which
helped prevent non-working backlights on some machines. Turns out that
the original sequence was the right thing to do for a different set of
machines. Worse, setting the backlight level _after_ enabling it seems
to reset it somehow. So we need to make that one conditional upon the
backlight having been reset to zero, and add the old one back.

Cargo-culting at it's best, but it seems to work.

Cc: stable@vger.kernel.org
Cc: Takashi Iwai <tiwai@suse.de>
Bugzilla: https://bugzilla.kernel.org/show_bug.cgi?id=47941Reviewed-by: NJani Nikula <jani.nikula@intel.com>
Acked-by: NTakashi Iwai <tiwai@suse.de>
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>

The BLC_PWM_CTL2 register does not exist before gen4. While at it, do a
slight drive by cleanup of the code.
Signed-off-by: NJani Nikula <jani.nikula@intel.com>
Reviewed-by: NPaulo Zanoni <paulo.r.zanoni@intel.com>
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>

But disabled by default. This essentially reverts

commit bcd5023c
Author: Dave Airlie <airlied@redhat.com>
Date:   Mon Mar 14 14:17:55 2011 +1000

    drm/i915: disable opregion lid detection for now

but leaves the autodetect mode disabled. There's also the explicit lid
status option added in

commit fca87409
Author: Chris Wilson <chris@chris-wilson.co.uk>
Date:   Thu Feb 17 13:44:48 2011 +0000

    drm/i915: Add a module parameter to ignore lid status

Which overloaded the meaning for the panel_ignore_lid parameter even
more. To fix up this mess, give the non-negative numbers 0,1 the
original meaning back and use negative numbers to force a given state.
So now we have

1  - disable autodetect, return unknown
0  - enable autodetect
-1 - force to disconnected/lid closed
-2 - force to connected/lid open

v2: My C programmer license has been revoked ...

v3: Beautify the code a bit, as suggested by Chris Wilson.

Bugzilla: https://bugzilla.kernel.org/show_bug.cgi?id=27622Tested-by: NAndreas Sturmlechner <andreas.sturmlechner@gmail.com>
Reviewed-by: NChris Wilson <chris@chris-wilson.co.uk>
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>

dev_priv has grown way too big, and grouping memebers into substructs
and moving them out of line helps re-gain some overview.

Unfortunatley I couldn't just call the substruct save and drop the prefix, since
that will make most member names clash with registers #defines. Changes in
i915_drv.h done by hand, everything else changed with
s/\<save\([A-Z]*\)/regfile.save\1/ in vim.
Reviewed-by: NJesse Barnes <jbarnes@virtuousgeek.org>
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>

commit 28dcc2d6
Author: Jani Nikula <jani.nikula@intel.com>
Date:   Mon Sep 3 16:25:12 2012 +0300

    drm/i915: do not expose a dysfunctional backlight interface to userspace

prevents backlight interface creation if the BIOS has not set the backlight
PWM CTL registers that contain the max PWM value. It's apparently normal on
those machines, so demote the message about it to debug level.
Reported-by: NOrion Poplawski <orion@cora.nwra.com>
Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=56330Signed-off-by: NJani Nikula <jani.nikula@intel.com>
Reviewed-by: NChris Wilson <chris@chris-wilson.co.uk>
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>

Pave the way for sharing some logic between eDP and LVDS.

Based on earlier work by Chris Wilson <chris@chris-wilson.co.uk>

CC: Chris Wilson <chris@chris-wilson.co.uk>
Signed-off-by: NJani Nikula <jani.nikula@intel.com>
Reviewed-by: NJesse Barnes <jbarnes@virtuousgeek.org>
Reviewed-by: NChris Wilson <chris@chris-wilson.co.uk>
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>

Create a generic struct intel_panel for sharing a data structure and code
between eDP and LVDS panels. Add the new struct to intel_connector so that
later on we can have generic EDID and mode reading functions with EDID
caching that transparently fallback to fixed mode when EDID is not
available.

Add intel_panel as a dummy first, and move data (such as the mentioned
fixed mode) to it in later patches.

Based on earlier work by Chris Wilson <chris@chris-wilson.co.uk>

CC: Chris Wilson <chris@chris-wilson.co.uk>
Signed-off-by: NJani Nikula <jani.nikula@intel.com>
Reviewed-by: NJesse Barnes <jbarnes@virtuousgeek.org>
Reviewed-by: NChris Wilson <chris@chris-wilson.co.uk>
[danvet: Fixup tiny conflict in intel_dp_destroy.]
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>

Get rid of saved int_lvds_connector and int_edp_connector in
drm_i915_private.
Signed-off-by: NJani Nikula <jani.nikula@intel.com>
Reviewed-by: NJesse Barnes <jbarnes@virtuousgeek.org>
Reviewed-by: NChris Wilson <chris@chris-wilson.co.uk>
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>

Previously intel_panel_setup_backlight() would create a sysfs backlight
interface with max brightness of 1 if it was unable to figure out the max
backlight brightness. This rendered the backlight interface useless.

Do not create a dysfunctional backlight interface to begin with.
Signed-off-by: NJani Nikula <jani.nikula@intel.com>
Tested-by: NDavid Woodhouse <David.Woodhouse@intel.com>
Reviewed-by: NChris Wilson <chris@chris-wilson.co.uk>
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>

When you reopen the lid on a laptop with PCH, the panel suddenly goes
blank sometimes.  It seems because BLC_PWM_CPU_CTL register is cleared
to zero when BLC_PWM_CPU_CTL2 and BLC_PWM_PCH_CTL1 registers are
enabled.

This patch fixes the problem by moving the call of the function setting
BLC_PWM_CPU_CTL after enabling other two registers.
Reported-and-tested-by: NHugh Dickins <hughd@google.com>
Signed-off-by: NTakashi Iwai <tiwai@suse.de>
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>

This function isn't used outside of intel_panel.c, so make it static.
Signed-off-by: NStéphane Marchesin <marcheu@chromium.org>
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>

When we enable/disable the CPU backlight registers we can't forget to
enable/disable the PCH backlight registers. Since we're using the CPU
registers we should also unset the override bit.

Fixes a regression on the following commit:
  drm/i915: properly enable the blc controller on the right pipe

The commit just deleted the code that sets the PCH registers, so it
was relying on the values set by the BIOS. I told my BIOS to boot on
the DVI monitor instead of the LVDS panel, so I noticed the bug.
Signed-off-by: NPaulo Zanoni <paulo.r.zanoni@intel.com>
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>

On gen4+ we have a bitfield to specify from which pipe the backlight
controller should take it's clock. For PCH split platforms we've
already set these up, but only at initialization time. And without
taking into account the 3rd pipe added with ivb.

For gen4, we've completely ignored these. Although we do restrict lvds
to the 2nd pipe, so this is only a problem on machines where we boot
up with the lvds on the first pipe.

So restructure the code to enable the backlight on the right pipe at
modeset time.

v2: For odd reasons panel_enable_backlight gets called twice in a
modeset, so we can't WARN_ON in there if the backlight controller is
switched on already.

v3: backlight enable can also be called through dpms on, so the check
in there is legit. Update the comment to reflect that.
Tested-By: NKamal Mostafa <kamal@canonical.com>
Bugzilla: https://bugs.launchpad.net/bugs/954661
Cc: Carsten Emde <C.Emde@osadl.org>
Reviewed-by: NEugeni Dodonov <eugeni.dodonov@intel.com>
Signed-Off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>

We should only frob adjusted_mode. This is in preparation of
a massive patch by Laurent Pinchart to make the mode argument
const.

After the previous two prep patches the only thing left is to clean up
things a bit. I've opted to pass in an adjust_mode param to
dp_adjust_dithering because that way we can be sure to avoid
duplicating this logic between mode_valid and mode_fixup - which was
the cause behind a dp link bw calculation bug in the past.

Also mark the mode argument of pch_panel_fitting const.

v2: Split up the mode->clock => adjusted_mode->clock change,
as suggested by Chris Wilson.
Reported-by: NLaurent Pinchart <laurent.pinchart@ideasonboard.com>
Reviewed-by: NChris Wilson <chris@chris-wilson.co.uk>
Reviewed-by: NJesse Barnes <jbarnes@virtuousgeek.org>
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>

The power field was never correctly initialized.

[airlied: just took the two drm specific bits]
Signed-off-by: NCorentin Chary <corentin.chary@gmail.com>
Signed-off-by: NDave Airlie <airlied@redhat.com>

This regression has been introduced in

commit ca9bfa7e
Author: Daniel Vetter <daniel.vetter@ffwll.ch>
Date:   Sat Jan 28 14:49:20 2012 +0100

    drm/i915: fixup interlaced vertical timings confusion, part 1

Unfortunately that commit failed to take into account that the lvds
code does some special adjustements to the crtc timings for upscaling
an centering.

Fix this by explicitly computing crtc timings in the lvds mode fixup
function and setting a special flag in mode->private_flags if the crtc
timings have been adjusted.

v2: Add a comment to explain the new mode driver private flag,
suggested by Eugeni Dodonov.

v3: Kill the confusing and now redundant set_crtcinfo call in
intel_fixed_panel_mode, noticed by Chris Wilson.
Reported-and-Tested-by: NHans de Bruin <jmdebruin@xmsnet.nl>
Bugzilla: https://bugzilla.kernel.org/show_bug.cgi?id=43071Reviewed-by: NEugeni Dodonov <eugeni.dodonov@intel.com>
Reviewed-by: NChris Wilson <chris@chris-wilson.co.uk>
Signed-Off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>

Use a more current logging style.  Ensure that appropriate
logging messages are prefixed with "i915: ".

Convert printks to pr_<level>.  Align arguments.
Signed-off-by: NJoe Perches <joe@perches.com>
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>

A machine may need to invert the panel backlight brightness value. This
patch adds the infrastructure for a quirk to do so.
Signed-off-by: NCarsten Emde <C.Emde@osadl.org>
Reviewed-by: NChris Wilson <chris@chris-wilson.co.uk>
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>

Following the documentation of the Legacy Backlight Brightness (LBB)
Register in the configuration space of some Intel PCI graphics adapters,
setting the LBB register with the value 0x0 causes the backlight to be
turned off, and 0xFF causes the backlight to be set to 100% intensity
(http://download.intel.com/embedded/processors/Whitepaper/324567.pdf).
The Acer Aspire 5734Z, however, turns the backlight off at 0xFF and sets
it to maximum intensity at 0. In consequence, the screen of this systems
becomes dark at an early boot stage which makes it unusable. The same
inversion applies to the BLC_PWM_CTL I915 register. This problem was
introduced in kernel version 2.6.38 when the PCI device of this system
was first supported by the i915 KMS module.

This patch adds a parameter to the i915 module to enable inversion of
the brightness variable (i915.invert_brightness).
Signed-off-by: NCarsten Emde <C.Emde@osadl.org>
Reviewed-by: NChris Wilson <chris@chris-wilson.co.uk>
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>

We have a pretty decent confusion about vertical timings of interlaced
modes. Peter Ross has written a patch that makes interlace modes work
on a lot more platforms/output combinations by doubling the vertical
timings.

The issue with that patch is that core drm _does_ support specifying
whether we want these vertical timings in fields or frames, we just
haven't managed to consistently use this facility. The relavant
function is drm_mode_set_crtcinfo, which fills in the crtc timing
information.

The first thing to note is that the drm core keeps interlaced modes in
frames, but displays modelines in fields. So when the crtc modeset
helper copies over the mode into adjusted_mode it will already contain
vertical timings in half-frames. The result is that the fixup code in
intel_crtc_mode_fixup doesn't actually do anything (in most cases at
least).

Now gen3+ natively supports interlaced modes and wants the vertical
timings in frames. Which is what sdvo already fixes up, at least under
some conditions.

There are a few other place that demand vertical timings in fields
but never actually deal with interlaced modes, so use frame timings
for consistency, too. These are:
- lvds panel,
- dvo encoders - dvo is the only way gen2 could support interlaced
  mode, but currently we don't support any encoders that do.
- tv out - despite that the tv dac sends out an interlaced signal it
  expects a progressive mode pipe configuration.
All these encoders enforce progressive modes by resetting
interlace_allowed.

Hence we always want crtc vertical timings in frames. Enforce this in
our crtc mode_fixup function and rip out any redudant timing
computations from the encoders' mode_fixup function.

v2-4: Adjust the vertical timings a bit.

v5: Split out the 'subtract-one for interlaced' fixes.

v6: Clarify issues around tv-out and gen2.
Reviewed-by: NEugeni Dodonov <eugeni.dodonov@intel.com>
Reviewed-by: NPaulo Zanoni <paulo.r.zanoni@intel.com>
Tested-by: NPaulo Zanoni <paulo.r.zanoni@intel.com>
Tested-by: NChristopher Egert <cme3000@gmail.com>
Tested-by: NAlfonso Fiore <alfonso.fiore@gmail.com>
Signed-Off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>

There is an error in i915_read_blc_pwm_ctl, where the register values
are not being copied correctly.  BLC_PWM_CTL and BLC_PWM_CTL2 are
getting mixed up.  This patch fixes that so that saveBLC_PWM_CTL2 and
not saveBLC_PWM_CTL is copied to the BLC_PWM_CTL2 register.
Signed-off-by: NSimon Que <sque@chromium.org>
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>