This avoids redundantly passing an (inout) head and tail pointer to
gen7_append_oa_reports() from gen7_oa_read which doesn't need to
reference either itself.

Moving the head/tail reads and writes into gen7_append_oa_reports should
have no functional effect except to avoid some redundant head pointer
writes in cases where nothing was copied to userspace.

This is a stepping stone towards updating how the head and tail pointer
state is managed to improve the workaround for the OA unit's tail
pointer race. It reduces the number of places we need to read/write the
head and tail pointers.
Signed-off-by: NRobert Bragg <robert@sixbynine.org>
Reviewed-by: NMatthew Auld <matthew.auld@intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/20170511154345.962-5-lionel.g.landwerlin@intel.comSigned-off-by: NChris Wilson <chris@chris-wilson.co.uk>

There's no need for the driver to keep reading back the head pointer
from hardware since the hardware doesn't update it automatically. This
way we can treat any invalid head pointer value as a software/driver
bug instead of spurious hardware behaviour.

This change is also a small stepping stone towards re-working how
the head and tail state is managed as part of an improved workaround
for the tail register race condition.
Signed-off-by: NRobert Bragg <robert@sixbynine.org>
Reviewed-by: NMatthew Auld <matthew.auld@intel.com>
Signed-off-by: NChris Wilson <chris@chris-wilson.co.uk>
Link: http://patchwork.freedesktop.org/patch/msgid/20170511154345.962-4-lionel.g.landwerlin@intel.com

If the function for checking whether there is OA buffer data available
(during a poll or blocking read) has false positives then we want to
avoid a situation where the subsequent read() returns EAGAIN (after
a more accurate check) followed by a poll() immediately reporting
the same false positive POLLIN event and effectively maintaining a
busy loop until there really is data.

This makes sure that we clear the .pollin event status whenever we
return EAGAIN to userspace which will throttle subsequent POLLIN events
and repeated attempts to read to the 5ms intervals of the hrtimer
callback we have.
Signed-off-by: NRobert Bragg <robert@sixbynine.org>
Reviewed-by: NMatthew Auld <matthew.auld@intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/20170511154345.962-3-lionel.g.landwerlin@intel.comSigned-off-by: NChris Wilson <chris@chris-wilson.co.uk>

If I'm going to complain about a back-to-front convention then the least
I can do is not muddle the comment up too.
Signed-off-by: NRobert Bragg <robert@sixbynine.org>
Reviewed-by: NMatthew Auld <matthew.auld@intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/20170511154345.962-2-lionel.g.landwerlin@intel.comSigned-off-by: NChris Wilson <chris@chris-wilson.co.uk>

Some panel will default to zero brightness when turning the
panel off and on again. This patch restores last brightness
level back when panel is turning back on.
Signed-off-by: NPuthikorn Voravootivat <puthik@chromium.org>
Reviewed-by: NDhinakaran Pandiyan <dhinakaran.pandiyan@intel.com>
Signed-off-by: NJani Nikula <jani.nikula@intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/20170511230225.142870-8-puthik@chromium.org

We should set backlight mode register before set register to
enable the backlight.
Signed-off-by: NPuthikorn Voravootivat <puthik@chromium.org>
Reviewed-by: NDhinakaran Pandiyan <dhinakaran.pandiyan@intel.com>
Signed-off-by: NJani Nikula <jani.nikula@intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/20170511230225.142870-6-puthik@chromium.org

intel_dp_aux_enable_backlight() assumed that the register
BACKLIGHT_BRIGHTNESS_CONTROL_MODE can only has value 01
(DP_EDP_BACKLIGHT_CONTROL_MODE_PRESET) when initialize.

This patch fixed that by handling all cases of that register.
Signed-off-by: NPuthikorn Voravootivat <puthik@chromium.org>
Reviewed-by: NDhinakaran Pandiyan <dhinakaran.pandiyan@intel.com>
Signed-off-by: NJani Nikula <jani.nikula@intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/20170511230225.142870-3-puthik@chromium.org

intel_dp_aux_backlight driver should check for the
DP_EDP_BACKLIGHT_BRIGHTNESS_AUX_SET_CAP before enable the driver.
Signed-off-by: NPuthikorn Voravootivat <puthik@chromium.org>
Reviewed-by: NDhinakaran Pandiyan <dhinakaran.pandiyan@intel.com>
Signed-off-by: NJani Nikula <jani.nikula@intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/20170511230225.142870-2-puthik@chromium.org

If a vma is already bound to a ppgtt, we incorrectly call
allocate_va_range again when doing a PIN_UPDATE, which will result in
over accounting within our paging structures, such that when we do
unbind something we don't actually destroy the structures and end up
inadvertently recycling them. In reality this probably isn't too bad,
but once we start touching PDEs and PDPEs for 64K/2M/1G pages this
apparent recycling will manifest into lots of really, really subtle
bugs.

v2: Fix the testing of vma->flags for aliasing_ppgtt_bind_vma

Fixes: ff685975 ("drm/i915: Move allocate_va_range to GTT")
Signed-off-by: NMatthew Auld <matthew.auld@intel.com>
Cc: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>
Reviewed-by: NChris Wilson <chris@chris-wilson.co.uk>
Link: http://patchwork.freedesktop.org/patch/msgid/20170512091423.26085-1-chris@chris-wilson.co.uk

During execlist_context_deferred_alloc() we presumed that the context is
uninitialised (we only just allocated the state object for it!) and
chose to optimise away the later call to engine->init_context() if
engine->init_context were NULL. This breaks with GVT's contexts that are
marked as pre-initialised to avoid us annoyingly calling
engine->init_context(). The fix is to not override ce->initialised if it
is already true.

Cc: Chris Wilson <chris@chris-wilson.co.uk>
Signed-off-by: NChuanxiao Dong <chuanxiao.dong@intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/1494497262-24855-1-git-send-email-chuanxiao.dong@intel.comReviewed-by: NChris Wilson <chris@chris-wilson.co.uk>
Signed-off-by: NChris Wilson <chris@chris-wilson.co.uk>

Due to the complex dependencies between workqueues and RCU, which
are not easily detected by lockdep, do not synchronize RCU during
shrinking.

On low-on-memory systems (mem=1G for example), the RCU sync leads
to all system workqueus freezing and unrelated lockdep splats are
displayed according to reports. GIT bisecting done by J. R.
Okajima points to the commit where RCU syncing was extended.

RCU sync gains us very little benefit in real life scenarios
where the amount of memory used by object backing storage is
dominant over the metadata under RCU, so drop it altogether.

 " Yeeeaah, if core could just, go ahead and reclaim RCU
   queues, that'd be great. "

  - Chris Wilson, 2016 (0eafec6d)

v2: More information to commit message.
v3: Remove "grep _rcu_" escapee from i915_gem_shrink_all (Andrea)

Fixes: c053b5a5 ("drm/i915: Don't call synchronize_rcu_expedited under struct_mutex")
Suggested-by: NChris Wilson <chris@chris-wilson.co.uk>
Reported-by: NJ. R. Okajima <hooanon05g@gmail.com>
Signed-off-by: NJoonas Lahtinen <joonas.lahtinen@linux.intel.com>
Reviewed-by: NChris Wilson <chris@chris-wilson.co.uk>
Tested-by: NHugh Dickins <hughd@google.com>
Tested-by: NAndrea Arcangeli <aarcange@redhat.com>
Cc: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
Cc: J. R. Okajima <hooanon05g@gmail.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Jani Nikula <jani.nikula@intel.com>
Cc: <stable@vger.kernel.org> # v4.11+
Link: http://patchwork.freedesktop.org/patch/msgid/1494414040-11160-1-git-send-email-joonas.lahtinen@linux.intel.com

We are using some scratch registers in MMIO based send function.
Make their base and count flexible in preparation of upcoming
GuC firmware/hardware changes. While around, change cmd len
parameter verification from WARN_ON to GEM_BUG_ON as we don't
need this all the time.

v2: call out WARN/GEM_BUG change in the commit msg (Daniele)
v3: don't overqualify the ints (Chris)
v4: rebase and use proper enum
Signed-off-by: NMichal Wajdeczko <michal.wajdeczko@intel.com>
Suggested-by: NDaniele Ceraolo Spurio <daniele.ceraolospurio@intel.com>
Cc: Daniele Ceraolo Spurio <daniele.ceraolospurio@intel.com>
Cc: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>
Cc: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Jani Nikula <jani.nikula@linux.intel.com>
Reviewed-by: NDaniele Ceraolo Spurio <daniele.ceraolospurio@intel.com>
Reviewed-by: NJoonas Lahtinen <joonas.lahtinen@linux.intel.com>
Acked-by: NJani Nikula <jani.nikula@intel.com>
Signed-off-by: NJoonas Lahtinen <joonas.lahtinen@linux.intel.com>

Prepare for alternate GuC notification mechanism.
Signed-off-by: NMichal Wajdeczko <michal.wajdeczko@intel.com>
Cc: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>
Cc: Daniele Ceraolo Spurio <daniele.ceraolospurio@intel.com>
Reviewed-by: NDaniele Ceraolo Spurio <daniele.ceraolospurio@intel.com>
[Joonas: Added newlines]
Signed-off-by: NJoonas Lahtinen <joonas.lahtinen@linux.intel.com>

commit a667fb40
Author: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>
Date:   Thu Dec 15 15:29:44 2016 +0100

    drm/i915: Disable all crtcs during driver unload, v2.

made sure that all crtc's are disabled on driver unload, but only the
following commit made sure all fb's are cleaned up correctly:

commit 9b2104f4
Author: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>
Date:   Tue Feb 21 14:51:40 2017 +0100

    drm/atomic: Make disable_all helper fully disable the crtc.

Finally remove this and add a WARN_ON when vma is set. It should
have been removed by intel_cleanup_plane_fb().
Signed-off-by: NMaarten Lankhorst <maarten.lankhorst@linux.intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/20170511082844.13965-2-maarten.lankhorst@linux.intel.comReviewed-by: NDaniel Vetter <daniel.vetter@ffwll.ch>

We shouldn't inspect crtc->state, instead grab the crtc state.
At this point the hw state verifier should be able to run even if
crtc->state has been updated (which cannot currently happen).
Signed-off-by: NMaarten Lankhorst <maarten.lankhorst@linux.intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/20170511082844.13965-1-maarten.lankhorst@linux.intel.comReviewed-by: NDaniel Vetter <daniel.vetter@ffwll.ch>

We are missing pieces of information that could be useful for GuC
debugging.

v2: Reuse some code (Joonas)

Cc: Daniele Ceraolo Spurio <daniele.ceraolospurio@intel.com>
Reviewed-by: NJoonas Lahtinen <joonas.lahtinen@linux.intel.com>
Signed-off-by: NOscar Mateo <oscar.mateo@intel.com>
[Joonas: Removed extra newline and s/uint32_t/u32/ for checkpatch.pl]
Signed-off-by: NJoonas Lahtinen <joonas.lahtinen@linux.intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/1494428691-20672-1-git-send-email-oscar.mateo@intel.com

The unconditionally fallback to the blocking wait_for resulted in
impressive fireworks at boot-up on my snb here. Make sure if we set
the slow timeout to 0 that we never ever sleep. The tail of the
callchain was

intel_wait_for_register
-> __intel_wait_for_register_fw
  -> usleep_range
     -> BOOM

It blew up in intel_crt_detect load detection code on the
ADPA_CRT_HOTPLUG_FORCE_TRIGGER in the ADPA register.

v2: Shut up gcc.

v3: Use uninitialized_var() (Chris).

Fixes: 05646543 ("drm/i915: Acquire uncore.lock over intel_uncore_wait_for_register()")
Cc: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Michal Wajdeczko <michal.wajdeczko@intel.com>
Cc: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>
Cc: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
Cc: Daniel Vetter <daniel.vetter@intel.com>
Cc: Jani Nikula <jani.nikula@linux.intel.com>
Reviewed-by: NChris Wilson <chris@chris-wilson.co.uk>
Signed-off-by: NDaniel Vetter <daniel.vetter@intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/1494429572-15118-1-git-send-email-daniel.vetter@ffwll.ch

It looks like simply writing all the cursor register every single
time might be slightly faster than checking to see of each of
them need to be written. So if any other register apart from
CURPOS needs to be written let's just write all the registers.

CURPOS is left as a special case mainly for 845/865 where we have to
disable the cursor to change many of the cursor parameters. This
introduces a slight chance of the cursor flickering when things get
updated (since we're not currently doing the vblank evade for cursor
updates). If we write CURPOS alone then that obviously can't happen.
And let's follow the same pattern in the i9xx code just for symmetry.
I wasn't able to see a singificant performance difference between
this and just writing all the registers unconditionally.
Signed-off-by: NVille Syrjälä <ville.syrjala@linux.intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/20170327185546.2977-16-ville.syrjala@linux.intel.comReviewed-by: NImre Deak <imre.deak@intel.com>

Supposedly 845/865 require only 32 byte alignment for CURBASE. Let's
relax the checks to allow that instead of demanding 4KiB alignment.
This will allow cursor panning in 8 pixel units.
Signed-off-by: NVille Syrjälä <ville.syrjala@linux.intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/20170327185546.2977-15-ville.syrjala@linux.intel.comReviewed-by: NImre Deak <imre.deak@intel.com>

The cursor plane doesn't have any kind of source offset register, so
the only form of panning possible is via a the base address register.
The alignment required by CURBASE ranges from 32B to 16KiB depending
on the platform. Let's make sure the user didn't ask for something
we can't do.

Obviously this is impossible to hit via the legacy cursor ioctl since
the src offsets are always 0, but via the plane/atomic ioctls the user
can ask for pretty much anything so we have to deal with this.
Signed-off-by: NVille Syrjälä <ville.syrjala@linux.intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/20170327185546.2977-14-ville.syrjala@linux.intel.comReviewed-by: NImre Deak <imre.deak@intel.com>

Bspec tells us that gen3 platforms need 4KiB alignment for CURBASE
rather than the 256 byte alignment required by i85x. Let's fix that
and pull the code to determine the correct alignment to a helper
function.
Signed-off-by: NVille Syrjälä <ville.syrjala@linux.intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/20170327185546.2977-13-ville.syrjala@linux.intel.comReviewed-by: NImre Deak <imre.deak@intel.com>

IVB introduced the CUR_FBC_CTL register which allows reducing the cursor
height down to 8 lines from the otherwise square cursor dimensions.
Implement support for it. CUR_FBC_CTL can't be used when the cursor
is rotated.

Commandeer the otherwise unused cursor->cursor.size to track the
current value of CUR_FBC_CTL to optimize away redundant CUR_FBC_CTL
writes, and to notice when we need to arm the update via CURBASE if
just CUR_FBC_CTL changes.

v2: Reverse the gen check to make it sane
v3: Only enable CUR_FBC_CTL when cursor is enabled, adapt to
    earlier code changes which means we now actually turn off
    the cursor when we're supposed to unlike v2
v4: Add a comment about rotation vs. CUR_FBC_CTL,
    rebase due to 'dirty' (Chris)
v5: Rebase to the atomic world
    Handle 180 degree rotation
    Add HAS_CUR_FBC()
v6: Rebase
v7: Rebase due to I915_WRITE_FW/uncore.lock
    s/size/fbc_ctl/
Signed-off-by: NVille Syrjälä <ville.syrjala@linux.intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/20170327185546.2977-12-ville.syrjala@linux.intel.comReviewed-by: NImre Deak <imre.deak@intel.com>

The cursor code currently ignores fb->pitches[0] (except when creating
the fb itself), and just uses the cursor_width*4 as the stride. Let's
make sure fb->pitches[0] actually matches what we expect it to be.

We can also relax the stride vs. cursor width relationship on 845/865
since the stride is programmed separately. The only constraint is that
width*cpp doesn't exceed the stride, and that's already been checked
by the core since it makes sure the entire plane fits within the fb.

We can also drop the bo size check as that's already checked when
we create the fb. That is the fb is guaranteed to fit within the bo.

v2: Rebase due to i845_cursor_ctl() and i9xx_cursor_ctl()
Signed-off-by: NVille Syrjälä <ville.syrjala@linux.intel.com>
Reviewed-by: Chris Wilson <chris@chris-wilson.co.uk> #v1
Link: http://patchwork.freedesktop.org/patch/msgid/20170327185546.2977-11-ville.syrjala@linux.intel.com

We have the maximum cursor dimensions stored in the mode_config, so
let's just consult that information instead of hardcoding the same
information in multiple places.

We still need to keep some per-platform checks as the limitations are
quite diverse.
Signed-off-by: NVille Syrjälä <ville.syrjala@linux.intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/20170327185546.2977-10-ville.syrjala@linux.intel.comReviewed-by: NImre Deak <imre.deak@intel.com>

The 845/865 and 830/855/9xx+ style cursor don't have that
much in common with each other, so let's just split the
.check_plane() hook into two variants as well.

v2: Keep the common stuff in one place (Chris)
v3: s/DRM_FORMAT_MOD_NONE/DRM_FORMAT_MOD_LINEAR/

Cc: Chris Wilson <chris@chris-wilson.co.uk>
Signed-off-by: NVille Syrjälä <ville.syrjala@linux.intel.com>
Reviewed-by: Chris Wilson <chris@chris-wilson.co.uk> #v1
Link: http://patchwork.freedesktop.org/patch/msgid/20170327185546.2977-9-ville.syrjala@linux.intel.com

There should be no need to do posting reads between all the cursor
register accessess. Let's just drop them.

v2: Rebase due to I915_WRITE_FW() and uncore.lock
Signed-off-by: NVille Syrjälä <ville.syrjala@linux.intel.com>
Reviewed-by: Chris Wilson <chris@chris-wilson.co.uk> #v1
Link: http://patchwork.freedesktop.org/patch/msgid/20170327185546.2977-8-ville.syrjala@linux.intel.com

Supposedly on some platforms we can get extra atomicity guarantees for
CURPOS if we write it between the CURCNTR and CURBASE. Let's move the
CURPOS handling into the platform specific hooks to make the possible
without having to pass the calculated CURPOS around. And while at it,
do the same for the CURBASE to avoid passing that either.

v2: Use I915_WRITE_FW() and grab uncore.lock
Signed-off-by: NVille Syrjälä <ville.syrjala@linux.intel.com>
Reviewed-by: Chris Wilson <chris@chris-wilson.co.uk> #v1
Link: http://patchwork.freedesktop.org/patch/msgid/20170327185546.2977-7-ville.syrjala@linux.intel.com

Move the CURPOS calculations to seprate function. This will allow
sharing the code between the 845/865 vs. others codepaths when we
otherwise split them apart.

v2: Don't pass intel_plane as it's not needed
Signed-off-by: NVille Syrjälä <ville.syrjala@linux.intel.com>
Reviewed-by: NChris Wilson <chris@chris-wilson.co.uk>
Link: http://patchwork.freedesktop.org/patch/msgid/20170327185546.2977-6-ville.syrjala@linux.intel.com

Move cursor_base, cursor_cntl, and cursor_size from intel_crtc
into intel_plane so that we don't need the crtc for cursor stuff
so much.

Also entirely nuke cursor_addr which IMO doesn't provide any benefit
since it's not actually used by the cursor code itself. I'm not 100%
sure what the SKL+ DDB is code is after by looking at cursor_addr so
I just make it do its checks unconditionally. If that's not correct
then we should likely replace it with somehting like
plane_state->visible.
Signed-off-by: NVille Syrjälä <ville.syrjala@linux.intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/20170327185546.2977-5-ville.syrjala@linux.intel.comReviewed-by: NImre Deak <imre.deak@intel.com>

The remaining cursor base address calculations are spread
around into several different locations. Just pull it all
into one place.

v2: Don't pass intel_plane as we don't really need it
Signed-off-by: NVille Syrjälä <ville.syrjala@linux.intel.com>
Reviewed-by: NChris Wilson <chris@chris-wilson.co.uk>
Link: http://patchwork.freedesktop.org/patch/msgid/20170327185546.2977-4-ville.syrjala@linux.intel.com

Streamline things by passing intel_plane and intel_crtc instead of
the drm types to our plane hooks.

v2: s/ilk/g4x/ in sprite code
Signed-off-by: NVille Syrjälä <ville.syrjala@linux.intel.com>
Reviewed-by: NChris Wilson <chris@chris-wilson.co.uk>
Link: http://patchwork.freedesktop.org/patch/msgid/20170327185546.2977-3-ville.syrjala@linux.intel.com

Signed-off-by: NVille Syrjälä <ville.syrjala@linux.intel.com>
Reviewed-by: NChris Wilson <chris@chris-wilson.co.uk>
Link: http://patchwork.freedesktop.org/patch/msgid/20170327185546.2977-2-ville.syrjala@linux.intel.com

Now that the watermarks are in order, it should be safe to enable sprite
planes on g4x. We alreday have the code in fact, we just call it ilk_.
Let's rename to g4x_ and let it loose.
Signed-off-by: NVille Syrjälä <ville.syrjala@linux.intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/20170421181432.15216-16-ville.syrjala@linux.intel.comReviewed-by: NMaarten Lankhorst <maarten.lankhorst@linux.intel.com>

Add a tracepoint for watermark programming on g4x, similar to what we
have on vlv/chv. Should help in debugging watermark programming sequence
issues.
Signed-off-by: NVille Syrjälä <ville.syrjala@linux.intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/20170421181432.15216-15-ville.syrjala@linux.intel.comReviewed-by: NMaarten Lankhorst <maarten.lankhorst@linux.intel.com>

I don't see why we couldn't use the HPLL watermarks on g4x. So let's
enable them. Let's assume a 35 usec memory latency for the HPLL mode.
That's roughly what PNV uses.

Based on the behaviour of the ELK box I have 35 usec is probably
overkill. Actually all the current latency values used seem overkill as
I can reduce them pretty drastically before I start to see underruns.
But let's play things a bit safe for now.
Signed-off-by: NVille Syrjälä <ville.syrjala@linux.intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/20170421181432.15216-14-ville.syrjala@linux.intel.comReviewed-by: NMaarten Lankhorst <maarten.lankhorst@linux.intel.com>

Implement proper two stage watermark programming for g4x. As with
other pre-SKL platforms, the watermark registers aren't double
buffered on g4x. Hence we must sequence the watermark update
carefully around plane updates.

The code is quite heavily modelled on the VLV/CHV code, with some
fairly significant differences due to the different hardware
architecture:
* g4x doesn't use inverted watermark values
* CxSR actually affects the watermarks since it controls memory self
  refresh in addition to the max FIFO mode
* A further HPLL SR mode is possible with higher memory wakeup
  latency
* g4x has FBC2 and so it also has FBC watermarks
* max FIFO mode for primary plane only (cursor is allowed, sprite is not)
* g4x has no manual FIFO repartitioning
* some TLB miss related workarounds are needed for the watermarks

Actually the hardware is quite similar to ILK+ in many ways. The
most visible differences are in the actual watermakr register
layout. ILK revamped that part quite heavily whereas g4x is still
using the layout inherited from earlier platforms.

Note that we didn't previously enable the HPLL SR on g4x. So in order
to not introduce too many functional changes in this patch I've not
actually enabled it here either, even though the code is now fully
ready for it. We'll enable it separately later on.
Signed-off-by: NVille Syrjälä <ville.syrjala@linux.intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/20170421181432.15216-13-ville.syrjala@linux.intel.comReviewed-by: NMaarten Lankhorst <maarten.lankhorst@linux.intel.com>

The documentation I've seen doesn't actually specify which watermarks
need the TLB miss w/a. Currently we only apply the w/a to the normal
watermarks for both primary and cursor planes. Since the documentation
doesn't explicitly say anything I'm going to assume that the w/a should
equally apply to the SR/HPLL watermarks. So let's do that.
Signed-off-by: NVille Syrjälä <ville.syrjala@linux.intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/20170421181432.15216-12-ville.syrjala@linux.intel.comReviewed-by: NMaarten Lankhorst <maarten.lankhorst@linux.intel.com>

All platforms until SKL compute their watermarks essentially
using the same method1/small buffer and method2/large buffer
formulas. Most just open code it in slightly different ways.
Let's pull it all into common helpers. This makes it a little
easier to spot the actual differences.

While at it try to add some docs explainign what the formulas
are trying to do.
Signed-off-by: NVille Syrjälä <ville.syrjala@linux.intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/20170421181432.15216-11-ville.syrjala@linux.intel.comReviewed-by: NMaarten Lankhorst <maarten.lankhorst@linux.intel.com>

Pull the g4x TLB miss w/a calculation into a small helper.
Signed-off-by: NVille Syrjälä <ville.syrjala@linux.intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/20170421181432.15216-10-ville.syrjala@linux.intel.comReviewed-by: NMaarten Lankhorst <maarten.lankhorst@linux.intel.com>

The g4x watermark TLB miss workaround requires that we bump up the
watermark by the difference between 8 full lines and the FIFO size.
Unfortunately the way we compute it at the moment ignores the size
of the pixels. The code also used the primary plane width as the
cursor width when computing the TLB miss w/a for the cursor.
Let's fix both problems.
Signed-off-by: NVille Syrjälä <ville.syrjala@linux.intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/20170421181432.15216-9-ville.syrjala@linux.intel.comReviewed-by: NMaarten Lankhorst <maarten.lankhorst@linux.intel.com>