v2: use correct register
v3: remove extra hunks, pull in register definitions & offset check directly
v4: add GT1 vs GT2 distinction for IVB portion (Ben)

References: https://bugs.freedesktop.org/show_bug.cgi?id=50233Reviewed-by: NBen Widawsky <ben@bwidawsk.net>
Signed-off-by: NJesse Barnes <jbarnes@virtuousgeek.org>
Reviewed-by: NAntti Koskipää <antti.koskipaa@intel.com>
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>

Needs to be set on every context restore as well, so set it as part of
the initial state so we can save/restore it.  Note this removes the IVB
workaround value from VLV and uses the default value, just adding in the
L3 cache aging disable bit, since the IVB value is wrong for VLV.
Signed-off-by: NJesse Barnes <jbarnes@virtuousgeek.org>
Reviewed-by: NAntti Koskipää <antti.koskipaa@intel.com>
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>

Now that we no longer pretend to have flexibility in matching any
north display block with any pch, we can ditch this.

v2: Fix the embarassing rebase fail that Paulo Zanoni spotted.
Reviewed-by: NPaulo Zanoni <paulo.r.zanoni@intel.com>
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>

Found in Bspec vol4h South Display Engine Registers [CPT, PPT],
section "5.3.1  TRANS_CHICKEN_1—Transcoder Chicken Bits 1"

v2: Make it compile.
Reviewed-by: NPaulo Zanoni <paulo.r.zanoni@intel.com>
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>

We need to set the timing override chicken bit after fdi link training
has completed and before we enable the transcoder. We also have to
clear that bit again after disabling the pch transcoder.

See "Graphics BSpec: vol4g North Display Engine Registers [IVB],
Display Mode Set Sequence" and "Graphics BSpec: vol4h South Display
Engine Registers [CPT, PPT], South Display Engine Transcoder and FDI
Control, Transcoder Debug and DFT, TRANS_CHICKEN_2" bit 31:

"Workaround : Enable the override prior to enabling the transcoder.
Disable the override after disabling the transcoder."

While at it, use the _PIPE macro for the other TRANS_DP register.

v2: Keep the w/a as-is, but kill the original (but wrongly placed)
workaround introduced in

commit 3bcf603f
Author: Jesse Barnes <jbarnes@virtuousgeek.org>
Date:   Wed Jul 27 11:51:40 2011 -0700

    drm/i915: apply timing generator bug workaround on CPT and PPT

and

commit d4270e57
Author: Jesse Barnes <jbarnes@virtuousgeek.org>
Date:   Tue Oct 11 10:43:02 2011 -0700

    drm/i915: export a CPT mode set verification function

Note that this old code has unconditionally set the w/a, which might
explain why fdi link training sometimes silently fails, and especially
why the auto-train did not seem to work properly.

v3: Paulo Zanoni pointed out that this workaround is also required on
the LPT PCH. And Arthur Ranyan confirmed that this workaround is
requierd for all ports on the pch, not just DP: The important part
is that the bit is set whenever the pch transcoder is enabled, and
that it is _not_ set while the fdi link is trained. It is also
important that the pch transcoder is fully disabled, i.e. we have to
wait for bit 30 to clear before clearing the w/a bit.

Hence move to workaround into enable/disable_transcoder, where the pch
transcoder gets enabled/disabled.

v4: Whitespace changes dropped.

v5: Don't run the w/a on IBX, we only need it on CPT/PPT and LPT.

v6:
- resolve conflicts with Paulo's big hsw vga rework
- s/!IBX/CPT since hsw paths are now all separate, and Paulo's patch
  to implement the equivalent w/a for LPT is already merged.

Cc: Jesse Barnes <jbarnes@virtuousgeek.org>
Cc: Paulo Zanoni <przanoni@gmail.com>
Cc: Arthur Ranyan <arthur.j.runyan@intel.com>
Reviewed-by: Paulo Zanoni <paulo.r.zanoni@intel.com> (v5)
Reviewed-by: Jesse Barnes <jbarnes@virtuousgeek.org> (v5)
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>

Fix power well control state by reading real register offset.
Signed-off-by: NZhenyu Wang <zhenyuw@linux.intel.com>
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>

Comment says for eaglelake/cantiga, but it's listed in the ilk table,
too. So apply it to both.
Reviewed-by: NChris Wilson <chris@chris-wilson.co.uk>
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>

We were programming register 0x42020 twice on those platforms. Once
should be enough.
Signed-off-by: NDamien Lespiau <damien.lespiau@intel.com>
Reviewed-by: NPaulo Zanoni <paulo.r.zanoni@intel.com>
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>

With the consolidated registers, it appears that we're setting the same
bis several times. Let's just collect the bits we want to set and program
it once.

v2: More cleanup. Also program 0x42004 and 0x45000 for FBC on non
    mobile platforms (Paulo Zanoni)
Signed-off-by: NDamien Lespiau <damien.lespiau@intel.com>
[danvet: Undo the functional change as discussed on irc.]
Reviewed-by: NPaulo Zanoni <paulo.r.zanoni@intel.com>
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>

Register 0x42020 was defined twice under the names PCH_DSPCLK_GATE_D and
ILK_DSPCLK_GATE. This patch consolidate the 2 sets of defines in one.

The transforms done are:

PCH_DSPCLK_GATE_D    -> ILK_DSPCLK_GATE_D
ILK_DSPCLK_GATE      -> ILK_DSPCLK_GATE_D

DPARBUNIT_CLOCK_GATE_DISABLE -> ILK_DPARBUNIT_CLOCK_GATE_DISABLE
ILK_DPARB_CLK_GATE           -> ILK_DPARBUNIT_CLOCK_GATE_DISABLE

DPFDUNIT_CLOCK_GATE_DISABLE -> ILK_DPFDUNIT_CLOCK_GATE_DISABLE
ILK_DPFD_CLK_GATE           -> ILK_DPFDUNIT_CLOCK_GATE_DISABLE
ILK_CLK_FBC                 -> ILK_DPFDUNIT_CLOCK_GATE_DISABLE

DPFCRUNIT_CLOCK_GATE_DISABLE -> ILK_DPFCRUNIT_CLOCK_GATE_DISABLE
ILK_DPFC_DIS1                -> ILK_DPFCRUNIT_CLOCK_GATE_DISABLE

DPFCUNIT_CLOCK_GATE_DISABLE -> ILK_DPFCUNIT_CLOCK_GATE_DISABLE
ILK_DPFC_DIS2               -> ILK_DPFCUNIT_CLOCK_GATE_DISABLE

We have a VHRUNIT_CLOCK_GATE_DISABLE define for the pre-ILK DSPCLK_GATE_D.
Even if the same bit is used in ILK_DSPCLK_GATE_D, other bits in the
register change, so I went with re-defining it, well more precisely rename
IVB_VRHUNIT_CLK_GATE, which is not specific to IVB+. So:

IVB_VRHUNIT_CLK_GATE       -> ILK_VHRUNIT_CLOCK_GATE_DISABLE
VHRUNIT_CLOCK_GATE_DISABLE -> ILK_VHRUNIT_CLOCK_GATE_DISABLE (ILK+ code)

This commit is only a renaming commit, further commits will clean up the
logic.

v2: Rename bit 5 and 7 to _ENABLE as setting them to 1 enables clock
    gating on their respective units, contrary to all of the other bits
    (Paulo Zanoni)
Signed-off-by: NDamien Lespiau <damien.lespiau@intel.com>
Reviewed-by: NPaulo Zanoni <paulo.r.zanoni@intel.com>
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>

Single-threaded forcewake was only used on some early pre-production
ivybridge machines, all the latest ones should use mt forcewake. And
we already assume this in other places of the code (e.g. DERRMR
support in the ddx, or the latest intel_gt_reset patch to reset any
lingering forcewake references left behind by the bios), so don't
bother here, too.
Reviewed-by: NMika Kuoppala <mika.kuoppala@intel.com>
Reviewed-by: NJesse Barnes <jbarnes@virtuousgeek.org>
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>

Some BIOSes may forcibly suspend RC6 during their operation which
trigger a warning as we find the hardware in a perplexing state upon
first use. So far that appears to be the worst symptom as fortuituously
we use the same values as the BIOS for programming the FORCEWAKE register.
Reported-by: NOleksij Rempel <bug-track@fisher-privat.net>
Signed-off-by: NChris Wilson <chris@chris-wilson.co.uk>
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>

No functional change, but reserves 0x2 for use by userspace.
Signed-off-by: NChris Wilson <chris@chris-wilson.co.uk>
Acked-by: NJesse Barnes <jbarnes@virtuousgeek.org>
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>

BIOS should be setting the minimum voltage for rc6 to be 450mV. Old or
buggy BIOSen may not be doing this, so we correct it for them. Ideally
customers should update the BIOS as only it would know the optimal
values for the platform, so we leave that fact as a DRM_ERROR for the
user to see.

Unfortunately this isn't fixing any of the issues it was targeted to
fix, but it is documented that we must do it.

CC: Jesse Barnes <jbarnes@virtuousgeek.org>
CC: Matt Turner <mattst88@gmail.com>
Signed-off-by: NBen Widawsky <ben@bwidawsk.net>
Reviewed-by: NJesse Barnes <jbarnes@virtuousgeek.org>
[danvet: bikeshedded loglevel of the "your bios is broken message" to
debug.]
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>

There is a special mechanism for communicating with the PCU already
being used for the ring frequency stuff. As we'll be needing this for
other commands, extract it now to make future code less error prone and
the current code more reusable.

I'm not entirely sure if this code matches 1:1 with the previous code
behaviorally. Functionally however, it should be the same.

CC: Jesse Barnes <jbarnes@virtuousgeek.org>
Signed-off-by: NBen Widawsky <ben@bwidawsk.net>
Reviewed-by: NJesse Barnes <jbarnes@virtuousgeek.org>
[danvet: Fixup compile fail reported by Wu Fengguang.]
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>

A previous patch, namely:

commit bf97b276
Author: Daniel Vetter <daniel.vetter@ffwll.ch>
Date:   Wed Apr 11 20:42:41 2012 +0200

    drm/i915: implement w/a for incorrect guarband clipping

accidentally set bit 5 in 3D_CHICKEN, which has nothing to do with
clipping.  This patch changes it to be set in 3D_CHICKEN3, where it
belongs.

The game "Dante" demonstrates random clipping issues when guardband
clipping is enabled and bit 5 of 3D_CHICKEN3 isn't set.  So the
workaround is actually necessary.

Cc: Daniel Vetter <daniel.vetter@ffwll.ch>
Cc: Oliver McFadden <oliver.mcfadden@linux.intel.com>
Acked-by: NPaul Menzel <paulepanter@users.sourceforge.net>
Signed-off-by: NKenneth Graunke <kenneth@whitecape.org>
Reviewed-by: NMika Kuoppala <mika.kuoppala@intel.com>
Cc: stable@vger.kernel.org
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>

Introduced in commit 87f8020e:
  drm/i915: implement WaDisableEarlyCull for VLV and IVB

Notice that the original patch sent to the mailing list did not
include the Haswell chunk, it was added later.

The bit set by the commit does not exist on Haswell machines (at least
that's what the documentation says). Also, the commit gives me a GPU
hang every time we're loading the driver. So let's revert the Haswell
chunk, making the patch do only what its title actually says.
Signed-off-by: NPaulo Zanoni <paulo.r.zanoni@intel.com>
Reviewed-by: NDamien Lespiau <damien.lespiau@intel.com>
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>

This workaround is only valid for IVB and VLV and the write triggers an
error on HSW.
Signed-off-by: NDamien Lespiau <damien.lespiau@intel.com>
Cc: Paulo Zanoni <paulo.r.zanoni@intel.com>
Reviewed-by: NPaulo Zanoni <paulo.r.zanonI@intel.com>
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>

For the next person that checks these kind of things, without having to
dig up the register definition.
Signed-off-by: NDamien Lespiau <damien.lespiau@intel.com>
Reviewed-by: NPaulo Zanoni <paulo.r.zanoni@intel.com>
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>

There's is another register (a read only, so no harm done) at 0x42020 on
Haswell GPUs. Let's just remove the write from the copy&paste that
introduced haswell_init_clock_gating().

A note for the interested reader, it does seem we have a duplication of
the 0x42020 register definition, hence the removal of 2 writes. That
duplication could be the object of a later patch.
Signed-off-by: NDamien Lespiau <damien.lespiau@intel.com>
Cc: Paulo Zanoni <paulo.r.zanoni@intel.com>
Reviewed-by: NPaulo Zanoni <paulo.r.zanoni@intel.com>
Tested-by: NPaulo Zanoni <paulo.r.zanoni@intel.com>
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>

Workaround for a culling optimization.
Signed-off-by: NJesse Barnes <jbarnes@virtuousgeek.org>
Reviewed-by: NBen Widawsky <ben@bwidawsk.net>
[danvet: Also apply to haswell, spotted by Damien.]
Reviewed-by: N"Lespiau, Damien" <damien.lespiau@intel.com>
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>

References: https://bugs.freedesktop.org/show_bug.cgi?id=50250Signed-off-by: NJesse Barnes <jbarnes@virtuousgeek.org>
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>

I can't even find how I figured this might be needed anymore. But sure
enough, the value I'm reading back on platforms doesn't match what the
docs recommends.

It seemed to fix Chris' GT1 in limited testing as well.
Tested-by: NChris Wilson <chris@chris-wilson.co.uk>
Cc: stable@vger.kernel.org
Signed-off-by: NBen Widawsky <ben@bwidawsk.net>
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>

Finishes commit 02d71956
Author: Daniel Vetter <daniel.vetter@ffwll.ch>
Date:   Thu Aug 9 16:44:54 2012 +0200

    drm/i915: properly guard ilk ips state

The core functions were annotated with their locking requirements, but
we overlooked that they were exported, without any control over the
locking, to debugfs. So in order to enable debugfs to read the registers
without triggering sanity checks, we change the exported entry points to
properly take the required locks before calling the core routines.
Reported-by: Nyangguang <guang.a.yang@intel.com>
Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=55304Signed-off-by: NChris Wilson <chris@chris-wilson.co.uk>
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>

With the new "standardized" sysfs interfaces we need to be a bit more
careful about setting the RPS values.

Because the sysfs code and the rps workqueue can run at the same time,
if the sysfs setter wins the race to the mutex, the workqueue can come
in and set a value which is out of range (ie. we're no longer protecting
by RPINTLIM).

I was not able to actually make this error occur in testing.
Signed-off-by: NBen Widawsky <ben@bwidawsk.net>
Reviewed-by: NChris Wilson <chris@chris-wilson.co.uk>
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>

In order to keep our cached values in sync with the hardware, we need a
posting read here.

CC: Chris Wilson <chris@chris-wilson.co.uk>
Signed-off-by: NBen Widawsky <ben@bwidawsk.net>
Reviewed-by: NChris Wilson <chris@chris-wilson.co.uk>
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>

Currently we've only frobbed this bit at irq_init time, but did
not restore it at resume time. Move it to the gen3 clock gating
function to fix this.

Notice while reading through code.

Cc: stable@vger.kernel.org (for 3.5 only)
Reviewed-by: NChris Wilson <chris@chris-wilson.co.uk>
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>

The same designer from the previous patch has told us to never read
FORCEWAKE. We only do this for the POSTING_READ(), so simply change that
to something within the same cacheline (for no reason in particular
other than it sounds nice). In the _mt case we can leverage
the gtfifodbg check for the POSTING_READ.

This partially reverts
commit 6af2d180
Author: Daniel Vetter <daniel.vetter@ffwll.ch>
Date:   Thu Jul 26 16:24:50 2012 +0200

    drm/i915: fix forcewake related hangs on snb

v2: commit message, comments about posting read from (Daniel)

Note: vlv forcewake doesn't need any changes for this special
treatment since FORCEWAKE_VLV is in a totally different register
range, and the readback FORCEWAKE_ACK_VLV readback that follows is in
the same range.
Signed-off-by: NBen Widawsky <ben@bwidawsk.net>
Acked-by: NChris Wilson <chris@chris-wilson.co.uk>
[danvet: Added note.]
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>

A designer familiar with the hardware has stated that the forcewake
timeout can theoretically be as high as a little over 1ms. Therefore we
modify our code to use 2ms (appropriate fudge and because we don't want
to round down).

Hopefully this can't prevent spurious timeouts.
Signed-off-by: NBen Widawsky <ben@bwidawsk.net>
Acked-by: NChris Wilson <chris@chris-wilson.oc.uk>
[danvet: again fix conflict with vlv patch.]
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>

It's used all over the place, and we want to be able to play around with
the value, apparently. Note that it doesn't touch other timeouts of the
same value (like gtfifo, and thread C0 wait).
Signed-off-by: NBen Widawsky <ben@bwidawsk.net>
Reviewed-by: NChris Wilson <chris@chris-wilson.oc.uk>
[danvet: fixup conflict with vlv forcewake patches.]
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>

<ickle> danvet: in the force wake, both DRM_ERRORs have the same string.
<ickle> useful for .txt shrinkage, horrible for debugging
Acked-by: NPaul Menzel <paulepanter@users.sourceforge.net>
Reviewed-by: NBen Widawsky <ben@bwidawsk.net>
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>

For some odd reasons, the vlv forcewake code is rather different from
all other platforms, with no clear justification. Adjust things:

- Don't check whether the gt is awake already (and bail out early), we
  need to grab a forcewake anyway. Otherwise the chip might go to
  sleep too early. And this would also screw up our forcewake
  accounting.
- Like all other platforms, check whether the gt has cleared the
  forcewake bit in the _ACK register before setting it again.
- Use _MASKED_BIT_ENABLE/DISABLE macros
- Only use bit0 of the forcewake reg, not all 16 bits.
- check the gtfifodb reg like on all other platforms in _put.
- Drop the POSTING_READs for consistency.

v2: Failure to git add ... again.

v3: Fixup the spelling fail a bit.
Tested-by: N"Purushothaman, Vijay A" <vijay.a.purushothaman@intel.com>
Tested-by: N"Widawsky, Benjamin" <benjamin.widawsky@intel.com>
Signed-Off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>

We've had and still have too many issues where the gpu turbo doesn't
quite to what it's supposed to do (or what we want it to do).

Adding a tracepoint to track when the desired gpu frequency changes
should help a lot in characterizing and understanding problematic
workloads.

Also, this should be fairly interesting for power tuning (and
especially noticing when the gpu is stuck in high frequencies, as has
happened in the past) and hence for integration into powertop and
similar tools.

Cc: Arjan van de Ven <arjan@linux.intel.com>
Reviewed-by: NChris Wilson <chris@chris-wilson.co.uk>
Acked-by: NPaul Menzel <paulepanter@users.sourceforge.net>
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>

Like with the equivalent change for gen6+ rps state, this helps in
clarifying the code (and in fixing a few places that have fallen through
the cracks in the locking review).
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>

It blows up. And hopefully this is the root-cause of the mysterious
rc6 related hang on ilk. For reference, the commit that enabled rc6 on
ilk again is:

commit 456470eb
Author: Daniel Vetter <daniel.vetter@ffwll.ch>
Date:   Wed Aug 8 23:35:40 2012 +0200

    drm/i915: enable rc6 on ilk again
Reported-by: NDave Airlie <airlied@gmail.com>
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>

Avoid stalling and waiting for the GPU by checking to see if there is
sufficient inactive space in the aperture for us to bind the buffer
prior to writing through the GTT. If there is inadequate space we will
have to stall waiting for the GPU, and incur overheads moving objects
about. Instead, only incur the clflush overhead on the target object by
writing through shmem.
Signed-off-by: NChris Wilson <chris@chris-wilson.co.uk>
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>

James Bottomley reported [1] a massive power regression, due to the
enabling of semaphores by default in 3.5. A workaround for him is to
again disable semaphores. And indeed, his system has a very hard time
to enter rc6 with semaphores enabled.

Ben Widawsky run around with a kill-a-watt a lot and noticed:
- There are indeed a few rare systems that seem to have a hard time
  entering rc6 when desktop-idle.
- One machine, The Indestructible Toshiba regressed in this behaviour
  between 3.5 and 3.6 in a merge commit! So rc6 behaviour with the
  current setting seems to be highly timing dependent and not robust
  at all.
- The behaviour James reported wrt semaphores seems to be a freak
  timing thing that only happens on his specific machine, confirming
  that enabling semaphores shouldn't reduce rc6 residency.

Now furthermore the Google ChromeOS guys reported [2] a while ago that
at least on some machines a simply a blinking cursor can keep the gpu
turbo at the highest frequency. This is because the current rps limits
used on snb/ivb are highly asymmetric.

On the theory that gpu turbo and rc6 tuning values are related, we've
tried whether the much saner looking (since much less asymmetric) rps
tuning values used for hsw would also help entering rc6 more robustly.

And it seems to mostly work, and we don't really have the resources to
through-roughly tune things in any better way: The values from the
ChromeOS ppl seem to fare a bit worse for James' machine, so I guess
we better stick with something vpg (the gpu hw/windows group)
provided, hoping that they've done their jobs.

Reference[1]: http://lists.freedesktop.org/archives/dri-devel/2012-July/025675.html
Reference[2]: http://lists.freedesktop.org/archives/intel-gfx/2012-July/018692.html
Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=53393Tested-by: NBen Widawsky <ben@bwidawsk.net>
Cc: stable@vger.kernel.org
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>

I have the faint hope that the total absence of any locking for the
rps code wasn't too good an idea and could very well have caused some
rc6 related regressions.

Unfortunately we've never managed to reproduce these issues on any of
our own machines, so the only way to go about this is to enable it and
see what happens.

While at it, kill some stale comments and improve the logging.
Acked-by: NBen Widawsky <ben@bwidawsk.net>
Reviewed-by: NDamien Lespiau <damien.lespiau@intel.com>
Signed-Off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>

We change the drps/ips sw/hw state from different callers: Our own irq
handler, the external intel-ips module and from process context. Most
of these callers don't take any lock at all.

Protect everything by making the mchdev_lock irqsave and grabbing it in
all relevant callsites. Note that we have to convert a few sleeps in the
drps enable/disable code to delays, but alas, I'm not volunteering to
restructure the code around a few work items.

For paranoia add a spin_locked assert to ironlake_set_drps, too.

v2: Move one access inside the lock protection. Caught by the
dev_priv->ips mass-rename ...

v3: Resolve rebase conflict.
Reviewed-by: NDamien Lespiau <damien.lespiau@intel.com>
Reviewed-by: NChris Wilson <chris@chris-wilson.co.uk>
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>

It's only ever a pointer to the global mchdev_lock, and we don't use
it at all.
Reviewed-by: NDamien Lespiau <damien.lespiau@intel.com>
Reviewed-by: NChris Wilson <chris@chris-wilson.co.uk>
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>