The register specification says we need to do this.

V2: Only write the register if the port is enabled.
Signed-off-by: NPaulo Zanoni <paulo.r.zanoni@intel.com>
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>

From this point on, the 'set_infoframe' functions always set the DIP
registers to a known state, so anything done will always be undone at
the modeset.
Signed-off-by: NPaulo Zanoni <paulo.r.zanoni@intel.com>
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>

This function is called when the pipe is disabled, so it always gets
the 50ms timeout.

This function is called once for each InfoFrame, so we actually get a
100ms timeout. Will be more if we add more InfoFrames.

Also, the spec says we need to "wait for a VSync to ensure completion
of any pending DIP transmissions", not for a VBlank. OTOH, the
register documentation suggests that the DIPs are sent *during* the
VSync, so shouldn't we be waiting until *after* the VSync to ensure
all DIPs are sent?

So this wait_for_vblank seems, besides useless, totally wrong.

If we ever want to change some specific InfoFrame on-the-fly (outside
of the modeset code), the code that changes the InfoFrame will have to
do the waiting itself, and properly.
Signed-off-by: NPaulo Zanoni <paulo.r.zanoni@intel.com>
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>

So the write_infoframe function can assume the DIP is on.

V2: Be more defensive and add WARN().
Signed-off-by: NPaulo Zanoni <paulo.r.zanoni@intel.com>
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>

Not once for each InfoFrame. Now we have a function that allows us to
do this.

[danvet: Paulo clarified on irc that a later bugfix patch needs this
cleanup.]
Signed-off-by: NPaulo Zanoni <paulo.r.zanoni@intel.com>
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>

This solves problems that happen when you alternate between HDMI and
DVI on the same port. I can reproduce these problems using DP->HDMI
and DP->DVI adapters on a DP port.

When you first plug HDMI and then plug DVI, you need to stop sending
DIPs, even if the port is in DVI mode (see the HDMI register spec). If
you don't stop sending DIPs, you'll see a pink vertical line on the
left side of the screen, some modes will give you a black screen, some
modes won't work correctly.

When you first plug DVI and then plug HDMI, you need to properly
enable the DIPs, otherwise the HW won't send them. After spending a
lot of time investigating this, I concluded that if the DIPs are
disabled, we should not write to the DIP register again because when
we do this, we also set the AVI InfoFrame frequency to "once", and
this seems to really confuse our hardware. Since this problem was not
exactly easy to debug, I'm adopting the defensive behavior and not
just avoing the "disable twice" sequence, but also explicitly
selecting the AVI InfoFrame and setting its frequency to a correct
one.

Also, move the "is_dvi" check from intel_set_infoframe to the
set_infoframes functions since now they're going to be the first ones
to deal with the DIP registers.

This patch adds the code to fix the problem, but it depends on the
removal of some code that can't be removed right now and will come
later in the patch series. The patch that we need is:
  - drm/i915: don't write 0 to DIP control at HDMI init

[danvet: Paulo clarified that this additional patch is only required
to make the fix complete, this patch here alone doesn't introduce a
regression but only partially solves the problem of randomly clearing
the dip registers.]

V2: Be even more defensive by selecting AVI and setting its frequency
outside the "is_dvi" check.
Signed-off-by: NPaulo Zanoni <paulo.r.zanoni@intel.com>
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>

We need a function that is able to fully 'set' the state of the DIP
registers to a known state.

Currently, we have the write_infoframe function that is called twice:
once for AVI and once for SPD. The problem is that write_infoframe
tries to keep the state of the DIP register as it is, changing only
the minimum necessary bits. The second problem is that
write_infoframe does twice (once for each time it is called) some
work that should be done only once (like waiting for vblank and
setting the port). If we add even more DIPs, it will do even more
repeated work.

This patch only adds the infrastructure keeping the code behavior the
same as before.

v2: add static keywords
Signed-off-by: NPaulo Zanoni <paulo.r.zanoni@intel.com>
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>

Paulo pointed out that gen4 re-used the SDVO registers for HDMI (the
separate HDMI registers where introduced with the first PCH) and so
g4x_hdmi_connected() never selected the right bit and always returned
disconnected.

Regression in

commit 8ec22b21
Author: Chris Wilson <chris@chris-wilson.co.uk>
Date:   Fri May 11 18:01:34 2012 +0100

    drm/i915/hdmi: Query the live connector status bit for G4x

Cc: Paulo Zanoni <przanoni@gmail.com>
Reviewed-by: NPaulo Zanoni <paulo.r.zanoni@intel.com>
Tested-by: NPaulo Zanoni <paulo.r.zanoni@intel.com>
Signed-off-by: NChris Wilson <chris@chris-wilson.co.uk>
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>

Wait request is poorly named IMO. After working with these functions for
some time, I feel it's much clearer to name the functions more
appropriately.

Of course we must update the callers to use the new name as well.

This leaves room within our namespace for a *real* wait request function
at some point.

Note to maintainer: this patch is optional.
Signed-off-by: NBen Widawsky <ben@bwidawsk.net>
Reviewed-by: NEugeni Dodonov <eugeni.dodonov@intel.com>
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>

This helps implement GL_ARB_sync but stops short of allowing full blown
sync objects. Finally we can use the new timed seqno waiting function
to allow userspace to wait on a buffer object with a timeout. This
implements that interface.

The IOCTL will take as input a buffer object handle, and a timeout in
nanoseconds (flags is currently optional but will likely be used for
permutations of flush operations). Users may specify 0 nanoseconds to
instantly check.

The wait ioctl with a timeout of 0 reimplements the busy ioctl. With any
non-zero timeout parameter the wait ioctl will wait for the given number
of nanoseconds on an object becoming unbusy. Since the wait itself does
so holding struct_mutex the object may become re-busied before this
completes. A similar but shorter race condition exists in the busy
ioctl.

v2: ETIME/ERESTARTSYS instead of changing to EBUSY, and EGAIN (Chris)
Flush the object from the gpu write domain (Chris + Daniel)
Fix leaked refcount in good case (Chris)
Naturally align ioctl struct (Chris)

v3: Drop lock after getting seqno to avoid ugly dance (Chris)

v4: check for 0 timeout after olr check to allow polling (Chris)

v5: Updated the comment. (Chris)

v6: Return -ETIME instead of -EBUSY when timeout_ns is 0 (Daniel)
Fix the commit message comment to be less ugly (Ben)
Add a warning to check the return timespec (Ben)

v7: Use DRM_AUTH for the ioctl. (Eugeni)
Signed-off-by: NBen Widawsky <ben@bwidawsk.net>
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>

The trace events adds whether or not the wait was blocking. Blocking in
this case means to hold struct_mutex (ie. no new work can be submitted
during the wait). The information is inherently racy.

The blocking information is racy since mutex_is_locked doesn't check
that the current thread holds the lock. The only other option would be
to pass the boolean information of whether or not the class was blocking
down through the stack which is less desirable.

v2: Don't do a trace event per loop. (Chris)
Only get blocking/non-blocking info (Chris)

v3: updated comment in code as well as commit msg (Daniel)
Add "(NB)" to trace information to remind us in 6 months (Ben)
Signed-off-by: NBen Widawsky <ben@bwidawsk.net>
Reviewed-by: NEugeni Dodonov <eugeni.dodonov@intel.com>
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>

Insert a wait parameter in the code so we can possibly timeout on a
seqno wait if need be. The code should be functionally the same as
before because all the callers will continue to retry if an arbitrary
timeout elapses.

We'd like to have nanosecond granularity, but the only way to do this is
with hrtimer, and that doesn't fit well with the needs of this code.

v2: Fix rebase error (Chris)
Return proper time even in wedged + signal case (Chris + Ben)
Use timespec constructs (Ben)
Didn't take Daniel's advice regarding the Frankenstein-ness of the
  function. I did try his advice, but in the end I liked the way the
  original code looked, better.

v3: Make wakeups far less frequent for infinite waits (Chris)

v4: Remove dummy_wait variable (Daniel)
Use raw monotonic time instead of jiffies (made the code a bit cleaner) (Ben)
Added a couple of warnings (Ben)

v5: Remove warnings (Daniel)
Use more accurate time diff for default case (Daniel)
Bikeshed for setting the return timespec in timeout case (Daniel)
s/jiffies/time in one of the comments
Signed-off-by: NBen Widawsky <ben@bwidawsk.net>
Reviewed-by: NEugeni Dodonov <eugeni.dodonov@intel.com>
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>

Unfortunately we can't abort a mode_set, but at least tell the user
that something might have gone wrong when setting the sdvo input or
output timing fails.
Reviewed-by: NChris Wilson <chris@chris-wilson.co.uk>
Signed-Off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>

- kill intel_sdvo->input_dtd, it's only used as a temporary variable,
  we store the preferred input mode in the adjusted mode at mode_fixup
  time.
- rename the function to make it clear what we want it to do (get the
  preferred mode) and say in a comment what it unfortunately does as a
  side-effect (set the new output timings).
Reviewed-by: NChris Wilson <chris@chris-wilson.co.uk>
Signed-Off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>

Signed-off-by: NChris Wilson <chris@chris-wilson.co.uk>
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>

Similar to g4x_dp_detect() we should probe the PORT_HOTPLUG_STATUS as to
whether the connector is active prior to attempting to retrieve the EDID.
Signed-off-by: NChris Wilson <chris@chris-wilson.co.uk>
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>

Note that gen3 is the only platform where we've got the bit
definitions right, hence the workaround of disabling sdvo hotplug
support on i945g/gm is not due to misdiagnosis of broken hotplug irq
handling ...
Signed-off-by: NChris Wilson <chris@chris-wilson.co.uk>
[danvet: add some blurb about sdvo hotplug fail on i945g/gm I've
wondered about while reviewing.]
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>

The status bits corresponding to the interrupt enable bits are the
"live" hotplug status bits, and reflect the current status of the port
(high for a detected connection, low for a disconnect). The actual bits
corresponding to the interrupt source are elsewhere. The actual event is
then determined by a combination of the interrupt flag and the current
live status (if the interrupt is active, but the current status is not,
then we have detected a disconnect.)
Signed-off-by: NChris Wilson <chris@chris-wilson.co.uk>
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>

Also as we set the HOTPLUG_EN to 0 during pre-install, we can simply set
it during post-install, and nor do we wish to enable unwanted hotplug
events.
Signed-off-by: NChris Wilson <chris@chris-wilson.co.uk>
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>

Merge tag 'drm-intel-next-2012-05-20' of git://people.freedesktop.org/~danvet/drm-intel into drm-core-next

Daniel wrote:

The last pull I'd like to squeeze into 3.5, safe for the hsw stuff mostly
bugfixes:
- last few patches for basic hsw enabling (Eugeni, infoframe support by
 Paulo)
- Fix up infoframe support, we've hopefully squashed all the cargo-culting
 in there (Paulo). Among all the issues, this finally fixes some of the
 infoframe regressions seen on g4x and snb systems.
- Fixup sdvo infoframe support, this fixes a regression from 2.6.37.
- Correctly enable semaphores on snb, we've enabled it already for 3.5,
 but the dmar check was slightly wrong.
- gen6 irq fixlets from Chris.
- disable gmbus on i830, the hw seems to be simply broken.
- fix up the pch pll fallout (Chris & me).
- for_each_ring macro from Chris - I've figured I'll merge this now to
 avoid backport pain.
- complain when the rps state isn't what we expect (Chris). Note that this
 is shockingly easy to hit and hence pretty much will cause a regression
 report. But it only tells us that the gpu turbo state got out of whack,
 a problem we know off since a long time (it cause the gpu to get stuck a
 a fixed frequency, usually the lowest one). Chris is working on a fix,
 but we haven't yet found a magic formula that works perfectly (only
 patches that massively reduce the frequency of this happening).
- MAINTAINERS patch, I'm now officially the guy to beat up."

* tag 'drm-intel-next-2012-05-20' of git://people.freedesktop.org/~danvet/drm-intel: (57 commits)
  drm/i915: IBX has a fixed pch pll to pch pipe mapping
  drm/i915: implement hsw_write_infoframe
  drm/i915: small hdmi coding style cleanups
  drm/i915: fixup infoframe support for sdvo
  drm/i915: Enable the PCH PLL for all generations after link training
  drm/i915: Convert BUG_ON(!pll->active) and friends to a WARN
  drm/i915: don't clobber the pipe param in sanitize_modesetting
  drm/i915: disable gmbus on i830
  drm/i915: Replace the feature tests for BLT/BSD with ring init checks
  drm/i915: Check whether the ring is initialised prior to dispatch
  drm/i915: Introduce for_each_ring() macro
  drm/i915: Assert that the transcoder is indeed off before modifying it
  drm/i915: hook Haswell devices in place
  drm/i915: prepare HDMI link for Haswell
  drm/i915: move HDMI structs to shared location
  drm/i915: add WR PLL programming table
  drm/i915: add support for DDI-controlled digital outputs
  drm/i915: detect digital outputs on Haswell
  drm/i915: program iCLKIP on Lynx Point
  drm/i915: program WM_LINETIME on Haswell
  ...

This should fix breakage introduced in

commit ee7b9f93
Author: Jesse Barnes <jbarnes@virtuousgeek.org>
Date:   Fri Apr 20 17:11:53 2012 +0100

    drm/i915: manage PCH PLLs separately from pipes

v2: Add a DRM_DEBUG_KMS message to explain why a given pll was
selected, suggested by Chris Wilson.

v3: Actually run git add.

Cc: Jesse Barnes <jbarnes@virtuousgeek.org>
Cc: Chris Wilson <chris@chris-wilson.co.uk>
Reviewed-by: NChris Wilson <chris@chris-wilson.co.uk>
Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=49712Signed-Off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>

Both the control and data registers are completely different now.
Signed-off-by: NPaulo Zanoni <paulo.r.zanoni@intel.com>
Reviewed-by: NEugeni Dodonov <eugeni.dodonov@intel.com>
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>

- Changed the coding style of auxiliary infoframe functions to make
  them smaller
- Fixed the column alignment of some function definitions
- Remove definition of "struct drm_crtc" in some places as they're
  used only to retrieve "struct intel_crtc"
Signed-off-by: NPaulo Zanoni <paulo.r.zanoni@intel.com>
Reviewed-by: NEugeni Dodonov <eugeni.dodonov@intel.com>
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>

At least the worst offenders:
- SDVO specifies that the encoder should compute the ecc. Testing also
  shows that we must not send the ecc field, so copy the dip_infoframe
  struct to a temporay place and avoid the ecc field. This way the avi
  infoframe is exactly 17 bytes long, which agrees with what the spec
  mandates as a minimal storage capacity (with the ecc field it would
  be 18 bytes).
- Only 17 when sending the avi infoframe. The SDVO spec explicitly
  says that sending more data than what the device announces results
  in undefined behaviour.
- Add __attribute__((packed)) to the avi and spd infoframes, for
  otherwise they're wrongly aligned. Noticed because the avi infoframe
  ended up being 18 bytes large instead of 17. We haven't noticed this
  yet because we don't use the uint16_t fields yet (which are the only
  ones that would be wrongly aligned).

This regression has been introduce by

3c17fe4b is the first bad commit
commit 3c17fe4b
Author: David Härdeman <david@hardeman.nu>
Date:   Fri Sep 24 21:44:32 2010 +0200

    i915: enable AVI infoframe for intel_hdmi.c [v4]

Patch tested on my g33 with a sdvo hdmi adaptor.

Bugzilla: https://bugzilla.kernel.org/show_bug.cgi?id=25732
Tested-by: Peter Ross <pross@xvid.org> (G35 SDVO-HDMI)
Reviewed-by: NEugeni Dodonov <eugeni.dodonov@intel.com>
Signed-Off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>

Reported-by: NJiri Slaby <jslaby@suse.cz>
Reported-by: NJonathan Nieder <jrnieder@gmail.com>
Signed-off-by: NDave Airlie <airlied@redhat.com>

Hidden away within one chipset specific path was the necessary logic to
turn on the PLL. This needs to be done everywhere in order for us to
drive any display! As such as soon as we tested on a non-CougarPoint
chipset, we failed to bring up any DisplayPorts and generated a nice set
of assertion failures in the process. At least one part of our logic is
working, the part that assumes that we have no idea what we are doing.

Reported-by: guang.a.yang@intel.com
References: https://bugs.freedesktop.org/show_bug.cgi?id=49712Signed-off-by: NChris Wilson <chris@chris-wilson.co.uk>
Reviewed-by: NJesse Barnes <jbarnes@virtuousgeek.org>
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>

Turn a fatal lockup into a merely blank display with lots of shouty
messages.

v2: Whilst in the area, convert the other BUG_ON into less fatal errors.
In particular, note that we may be called on a PCH platform not using
PLLs, such as Haswell, and so we do not always want to BUG_ON(!pll)
Signed-off-by: NChris Wilson <chris@chris-wilson.co.uk>
Signed-Off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>

... we need it later on in the function to clean up pipe <-> plane
associations. This regression has been introduced in

commit f47166d2
Author: Chris Wilson <chris@chris-wilson.co.uk>
Date:   Thu Mar 22 15:00:50 2012 +0000

    drm/i915: Sanitize BIOS debugging bits from PIPECONF

Spotted by staring at debug output of an (as it turns out) totally
unrelated bug.

v2: I've totally failed to do the s/pipe/i/ correctly, spotted by
Chris Wilson.
Reviewed-by: NChris Wilson <chris@chris-wilson.co.uk>
Reviewed-by: NEugeni Dodonov <eugeni.dodonov@intel.com>
Cc: stable@kernel.org (the regression was Cc: stable, too)
Signed-Off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>

The hw just returns garbage.

Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=49838Reported-and-tested-by: NVladyslav <DFEW.Entwickler@googlemail.com>
Acked-by: NChris Wilson <chris@chris-wilson.co.uk>
Signed-Off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>

When userspace asks whether the driver supports the BLT or BSD rings for
this chip, simply report whether those particular rings are initialised

v2: Use intel_ring_initialized()
Signed-off-by: NChris Wilson <chris@chris-wilson.co.uk>
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>

Rather than use the magic feature tests HAS_BLT/HAS_BSD just check
whether the ring we are about to dispatch the execbuffer on is
initialised.

v2: Use intel_ring_initialized()
Signed-off-by: NChris Wilson <chris@chris-wilson.co.uk>
Reviewed-by: NBen Widawsky <ben@bwidawsk.net>
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>

In many places we wish to iterate over the rings associated with the
GPU, so refactor them to use a common macro.

Along the way, there are a few code removals that should be side-effect
free and some rearrangement which should only have a cosmetic impact,
such as error-state.

Note that this slightly changes the semantics in the hangcheck code:
We now always cycle through all enabled rings instead of
short-circuiting the logic.

v2: Pull in a couple of suggestions from Ben and Daniel for
intel_ring_initialized() and not removing the warning (just moving them
to a new home, closer to the error).
Signed-off-by: NChris Wilson <chris@chris-wilson.co.uk>
Reviewed-by: NBen Widawsky <ben@bwidawsk.net>
[danvet: Added note to commit message about the small behaviour
change, suggested by Ben Widawsky.]
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>

Inspired by a recent regression that seems to confuse pch transcoder
state, let's be a bit more paranoid.

References: https://bugs.freedesktop.org/show_bug.cgi?id=49712
Cc: Jesse Barnes <jbarnes@virtuousgeek.org>
Signed-off-by: NChris Wilson <chris@chris-wilson.co.uk>
[danvet: Pimped commit message.]
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>

This patch enables i915 driver to handle Haswell devices. It should go in
last, when things are working stable enough.
Signed-off-by: NEugeni Dodonov <eugeni.dodonov@intel.com>
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>

On Haswell, we need to properly train the DDI buffers prior to enabling
HDMI, and enable the required clocks with correct dividers for the desired
frequency.

Also, we cannot simple reuse HDMI routines from previous generations of
GPU, as most of HDMI-specific stuff is being done via the DDI port
programming instead of HDMI-specific registers.

This commit take advantage of the WR PLL clock table which is in a
separate (previous) commit to select the right divisors for each mode.
Signed-off-by: NEugeni Dodonov <eugeni.dodonov@intel.com>
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>

Move intel_hdmi data structure and support functions to a shared location,
to allow their usage from intel_ddi module.
Reviewed-by: NJesse Barnes <jbarnes@virtuousgeek.org>
Signed-off-by: NEugeni Dodonov <eugeni.dodonov@intel.com>
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>

This table is used for programming WR PLL clocks, used by HDMI and DVI outputs.
I split it into a separate patch to simplify the HDMI enabling patch which was
getting huge.

Note that this table is a temporary solution for WR PLL programming. It
will be reworked into a more exact algorithm at a later stage. But for
now, it provides the most accurate clock setting solution, so we use it
here.
Signed-off-by: NEugeni Dodonov <eugeni.dodonov@intel.com>
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>

Those are driven by DDIs on Haswell architecture, so we need to keep track
of which DDI is being used on each output.
Reviewed-by: NJesse Barnes <jbarnes@virtuousgeek.org>
Signed-off-by: NEugeni Dodonov <eugeni.dodonov@intel.com>
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>

Digital port detection on Haswell is indicated by the presence of a bit in
DDI_BUF_CTL for port A, and by a different register for ports B, C and D.
So we check for those bits during the initialization time and let the hdmi
function know about those.

Note that this bit does not indicates whether the output is DP or HDMI.
However, the DDI buffers can be programmed in a way that is shared between
DP/HDMI and FDI/HDMI except for PORT E.

So for now, we detect those digital outputs as being HDMI, but proper DP
support is still pending.

Note that DDI A can only drive eDP, so we do not handle it here for hdmi
initialization.

v2: simplify Haswell handling logic

v3: use generic function for handling digital outputs.
Signed-off-by: NEugeni Dodonov <eugeni.dodonov@intel.com>
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>

The iCLKIP clock is used to drive the VGA pixel clock on the PCH. In order
to do so, it must be programmed to properly do the clock ticks according
to the divisor, phase direction, phase increments and a special auxiliary
divisor for 20MHz clock.

v2: calculate divisor values directly instead of relying on a table.

v3: merged a fix from Ben to properly check for invalid divider values.
Reviewed-by: NBen Widawsky <ben@bwidawsk.net>
Signed-off-by: NEugeni Dodonov <eugeni.dodonov@intel.com>
Signed-off-by: NBen Widawsky <ben@bwidawsk.net>
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>