Keep the intel_context as being the primary state for i915_request, with
the GEM context a backpointer from the low level state for the rarer
cases we need client information. Our goal is to remove such references
to clients from the backend, and leave the HW submission agnostic to
client interfaces and self-contained.
Signed-off-by: NChris Wilson <chris@chris-wilson.co.uk>
Cc: Andi Shyti <andi.shyti@intel.com>
Reviewed-by: NAndi Shyti <andi.shyti@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20191220101230.256839-1-chris@chris-wilson.co.uk

Since we added the context_alloc callback to intel_context_ops, we can
safely install a custom hook for the deferred virtual context allocation.
This means that all new contexts behave the same upon creation,
simplifying later code.
Signed-off-by: NChris Wilson <chris@chris-wilson.co.uk>
Cc: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
Cc: Andi Shyti <andi.shyti@intel.com>
Reviewed-by: NAndi Shyti <andi.shyti@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20191219232932.189197-1-chris@chris-wilson.co.uk

Avoid adding the retire workers to the virtual engine so that we don't
end up in the unenviable situation of trying to free the virtual engine
while its worker remains active.

Fixes: dc93c9b6 ("drm/i915/gt: Schedule request retirement when signaler idles")
Closes: https://gitlab.freedesktop.org/drm/intel/issues/867Signed-off-by: NChris Wilson <chris@chris-wilson.co.uk>
Cc: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
Cc: Mika Kuoppala <mika.kuoppala@linux.intel.com>
Cc: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>
Acked-by: NJoonas Lahtinen <joonas.lahtinen@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20191219221344.161523-1-chris@chris-wilson.co.uk

All the other display related tracepoints use intel_ instead
if i915_ as the prefix. Do the same for the pipe update
tracepoints so I don't always have to spend time looking for
them.
Signed-off-by: NVille Syrjälä <ville.syrjala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20191213133453.22152-6-ville.syrjala@linux.intel.comReviewed-by: NChris Wilson <chris@chris-wilson.co.uk>

I fumbled the conflict resolution a bit when applying the
fbc vblank wait w/a. Because of that we now call intel_fbc_pre_update()
twice. Remove the second redundant call.
Reported-by: NChris Wilson <chris@chris-wilson.co.uk>
Signed-off-by: NVille Syrjälä <ville.syrjala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20191213133453.22152-2-ville.syrjala@linux.intel.comReviewed-by: NChris Wilson <chris@chris-wilson.co.uk>

icl and tgl are still affected by the modulo 4 PLANE_OFFSET.y
underrun issue. Reject such configurations on all gen9+ platforms.

Can be reproduced easily with the following sequence of
hardware poking:
while {
  write FBC_CTL.enable=1
  wait for vblank

  write PLANE_OFFSET .x=0 .y=32
  write PLANE_SURF
  wait for vblank

  # if PLANE_OFFSET.y is multiple of 4 the underrun won't happen
  write PLANE_OFFSET .x=0 .y=31
  write PLANE_SURF
  wait for vblank

  # extra vblank wait is required here presumably
  # to get FBC into the proper state
  wait for vblank

  write FBC_CTL.enable=0
  # underrun happens some time after FBC disable
  wait for vblank
}

Both 8888 and 565 pixel formats and all tilinga formats
seem affected. Reproduced on KBL/GLK/ICL/TGL. BDW confirmed
not affected.

Closes: https://gitlab.freedesktop.org/drm/intel/issues/792Signed-off-by: NVille Syrjälä <ville.syrjala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20191213133453.22152-1-ville.syrjala@linux.intel.comReviewed-by: NImre Deak <imre.deak@intel.com>

Currently pointers to and from are not initialized and may contain
garbage values. This will cause uninitialized pointer reads in the
call to intel_frontbuffer_track and later checks to see if to and from
are null.  Fix this by ensuring to and from are initialized to NULL.

Addresses-Coverity: ("Uninitialised pointer read)"
Fixes: da42104f ("drm/i915: Hold reference to intel_frontbuffer as we track activity")
Signed-off-by: NColin Ian King <colin.king@canonical.com>
Reviewed-by: NChris Wilson <chris@chris-wilson.co.uk>
Signed-off-by: NChris Wilson <chris@chris-wilson.co.uk>
Link: https://patchwork.freedesktop.org/patch/msgid/20191219190916.24693-1-colin.king@canonical.com

When we park RPS, we set the GPU to run at minimum 'idle' frequency.
However, as the GPU is idle, we also disable the worker and RPS
interrupts - changing the RPS thresholds has no effect, it just incurs
extra changes to restore them when we unpark. So on parking, leave the
thresholds set to the current power level and so we expect them to be
valid for our restart.

References: https://gitlab.freedesktop.org/drm/intel/issues/848Signed-off-by: NChris Wilson <chris@chris-wilson.co.uk>
Cc: Andi Shyti <andi.shyti@intel.com>
Reviewed-by: NAndi Shyti <andi.shyti@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20191218210545.3975426-2-chris@chris-wilson.co.uk

Use non-forcewaked writes to queue RPS register changes that will take
effect when the write buffer is flushed, rather than wake the mmio
device for immediate effect. This is so that we can avoid a slow
forcewake dance upon unparking, and at our irregular updates.
Signed-off-by: NChris Wilson <chris@chris-wilson.co.uk>
Cc: Andi Shyti <andi.shyti@intel.com>
Reviewed-by: NAndi Shyti <andi.shyti@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20191218210545.3975426-1-chris@chris-wilson.co.uk

Knowing the round trip time of an engine is useful for tracking the
health of the system as well as providing a metric for the baseline
responsiveness of the engine. We can use the latter metric for
automatically tuning our waits in selftests and when idling so we don't
confuse a slower system with a dead one.

Upon idling the engine, we send one last pulse to switch the context
away from precious user state to the volatile kernel context. We know
the engine is idle at this point, and the pulse is non-preemptible, so
this provides us with a good measurement of the round trip time. It also
provides us with faster engine parking for ringbuffer submission, which
is a welcome bonus (e.g. softer-rc6).
Signed-off-by: NChris Wilson <chris@chris-wilson.co.uk>
Cc: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
Cc: Stuart Summers <stuart.summers@intel.com>
Reviewed-by: NJoonas Lahtinen <joonas.lahtinen@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20191219105043.4169050-1-chris@chris-wilson.co.uk
Link: https://patchwork.freedesktop.org/patch/msgid/20191219124353.8607-2-chris@chris-wilson.co.uk

Very similar to commit 4f88f874 ("drm/i915/gt: Schedule request
retirement when timeline idles"), but this time instead of coupling into
the execlists CS event interrupt, we couple into the breadcrumb
interrupt and queue a timeline's retirement when the last signaler is
completed. This should allow us to more rapidly park ringbuffer
submission, and so help reduce power consumption on older systems.

v2: Fixup intel_engine_add_retire() to handle concurrent callers

References: 4f88f874 ("drm/i915/gt: Schedule request retirement when timeline idles")
Signed-off-by: NChris Wilson <chris@chris-wilson.co.uk>
Cc: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
Cc: Mika Kuoppala <mika.kuoppala@linux.intel.com>
Reviewed-by: NJoonas Lahtinen <joonas.lahtinen@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20191219124353.8607-1-chris@chris-wilson.co.uk

Fix several issues with DSC power domains that did not take DSI
transcoders into account:

- On TGL+ we need to use PW2 for DSC on pipe A, not transcoder A. There
  is no longer an eDP transcoder, but there are two DSI transcoders
  which may be connected to pipe A.

- On TGL+ we need to use the pipe, not transcoder, power domains for DSC
  on pipes other than A. Again, there are DSI transcoders.

- On ICL we need to use PW2 for DSC also for DSI transcoders, not just
  for the eDP transcoder.

Using is_pipe_dsc() also adds the warning about ICL pipe A DSC, which
does not exist.

Cc: José Roberto de Souza <jose.souza@intel.com>
Cc: Manasi Navare <manasi.d.navare@intel.com>
Cc: Vandita Kulkarni <vandita.kulkarni@intel.com>
Reviewed-by: NVandita Kulkarni <vandita.kulkarni@intel.com>
Signed-off-by: NJani Nikula <jani.nikula@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20191212134728.18432-1-jani.nikula@intel.com

The check for cpu_transcoder != TRANSCODER_A is more magic than
necessary, and potentially misleading. Before TGL, DSC is supported on
pipe A if, and only if, it's used with eDP or DSI transcoders. No
functional changes.

Cc: Manasi Navare <manasi.d.navare@intel.com>
Cc: Vandita Kulkarni <vandita.kulkarni@intel.com>
Reviewed-by: NVandita Kulkarni <vandita.kulkarni@intel.com>
Signed-off-by: NJani Nikula <jani.nikula@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/f00e9d55ce20b256177222588780c660aa587cc3.1576081155.git.jani.nikula@intel.com

ICL eDP and DSI transcoders have a DSC engine separate from the
pipe. Abstract the register selection and fix it for ICL.

Add a warning for pipe A DSC on ICL; it does not exist.

Cc: Manasi Navare <manasi.d.navare@intel.com>
Cc: Vandita Kulkarni <vandita.kulkarni@intel.com>
Reviewed-by: NVandita Kulkarni <vandita.kulkarni@intel.com>
Signed-off-by: NJani Nikula <jani.nikula@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/01bcddcdf397b1c8eb859ed18ebe023fb64383d9.1576081155.git.jani.nikula@intel.com

Use the ddc pointer provided by the generic connector.
Signed-off-by: NAndrzej Pietrasiewicz <andrzej.p@collabora.com>
Acked-by: NSam Ravnborg <sam@ravnborg.org>
Reviewed-by: NEmil Velikov <emil.velikov@collabora.com>
Signed-off-by: NJani Nikula <jani.nikula@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20191128150130.26266-1-andrzej.p@collabora.com

Pass the correct variable as argument.
Signed-off-by: NLucas De Marchi <lucas.demarchi@intel.com>
Reviewed-by: NClinton Taylor <Clinton.A.Taylor@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20191217230529.25092-3-lucas.demarchi@intel.com

Instead of "ungated" use the same name for the variable as the bitfield,
making it clearer what's the intent of the checks.
Signed-off-by: NLucas De Marchi <lucas.demarchi@intel.com>
Reviewed-by: NClinton Taylor <Clinton.A.Taylor@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20191217230529.25092-2-lucas.demarchi@intel.com

This allows us to isolate reading and writing to the
ICL_DPCLKA_CFGCR0 during the sanitize phase.
Signed-off-by: NLucas De Marchi <lucas.demarchi@intel.com>
Reviewed-by: NClinton Taylor <Clinton.A.Taylor@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20191217230529.25092-1-lucas.demarchi@intel.com

When doing our global park, we like to be a good citizen and shrink our
slab caches (of which we have quite a few now), but each
kmem_cache_shrink() incurs a stop_machine() and so ends up being quite
expensive, causing machine-wide stalls. While ideally we would like to
throw away unused pages in our slab caches whenever it appears that we
are idling, doing so will require a much cheaper mechanism. In the
meantime use a delayed worked to impose a rate-limit that means we have
to have been idle for more than 2 seconds before we start shrinking.

References: https://gitlab.freedesktop.org/drm/intel/issues/848Signed-off-by: NChris Wilson <chris@chris-wilson.co.uk>
Cc: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
Reviewed-by: NTvrtko Ursulin <tvrtko.ursulin@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20191218094057.3510459-1-chris@chris-wilson.co.uk

Only signal the breadcrumbs from inside the irq_work, simplifying our
interface and calling conventions. The micro-optimisation here is that
by always using the irq_work interface, we know we are always inside an
irq-off critical section for the breadcrumb signaling and can ellide
save/restore of the irq flags.
Signed-off-by: NChris Wilson <chris@chris-wilson.co.uk>
Reviewed-by: NTvrtko Ursulin <tvrtko.ursulin@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20191217095642.3124521-7-chris@chris-wilson.co.uk

Avoid rc6 counter going backward in close to 0% RC6 scenarios like:

    15.005477996        114,246,613 ns   i915/rc6-residency/
    16.005876662            667,657 ns   i915/rc6-residency/
    17.006131417              7,286 ns   i915/rc6-residency/
    18.006615031 18,446,744,073,708,914,688 ns   i915/rc6-residency/
    19.007158361 18,446,744,073,709,447,168 ns   i915/rc6-residency/
    20.007806498                  0 ns   i915/rc6-residency/
    21.008227495          1,440,403 ns   i915/rc6-residency/

There are two aspects to this fix.

First is not assuming rc6 value zero means GT is asleep since that can
also mean GPU is fully busy and we do not want to enter the estimation
path in that case.

Second is ensuring monotonicity on the estimation path itself. I suspect
what is happening is with extremely rapid park/unpark cycles we get no
updates on the real rc6 and therefore have to careful not to
unconditionally trust use last known real rc6 when creating a new
estimation.

v2:
 * Simplify logic by not tracking the estimate but last reported value.
Signed-off-by: NTvrtko Ursulin <tvrtko.ursulin@intel.com>
Fixes: 16ffe73c ("drm/i915/pmu: Use GT parked for estimating RC6 while asleep")
Cc: Chris Wilson <chris@chris-wilson.co.uk>
Reviewed-by: Chris Wilson <chris@chris-wilson.co.uk> # v1
Reviewed-by: NChris Wilson <chris@chris-wilson.co.uk>
Link: https://patchwork.freedesktop.org/patch/msgid/20191217142057.1000-1-tvrtko.ursulin@linux.intel.com

Move all of haswell_crtc_disable() into the encoder
.post_disable() hooks. Now we're left with just
calling the .disable() and .post_disable() hooks
back to back.

I chose to move the code into the .post_disable() hook instead
of the .disable() hook as most of the sequence is currently
implemented in the .post_disable() hook.

We should collapse it all down to just one hook and then the
encoders can drive the modeset sequence fully. But that may
need some further refactoring as we currently call the
ddi .post_disable() hook from mst code and we can't just
replace that with a call to the ddi .disable() hook.

Should also follow up with similar treatment for the enable
sequence but let's start here where it's easier.

Cc: José Roberto de Souza <jose.souza@intel.com>
Cc: Manasi Navare <manasi.d.navare@intel.com>
Signed-off-by: NVille Syrjälä <ville.syrjala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20191213195217.15168-5-ville.syrjala@linux.intel.comReviewed-by: NJosé Roberto de Souza <jose.souza@intel.com>

To make life easier in the future let's pass the old crtc state
to intel_crtc_vblank_off() just like we already do for its
counterpart intel_crtc_vblank_on().

Cc: José Roberto de Souza <jose.souza@intel.com>
Cc: Manasi Navare <manasi.d.navare@intel.com>
Signed-off-by: NVille Syrjälä <ville.syrjala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20191213195217.15168-4-ville.syrjala@linux.intel.comReviewed-by: NJosé Roberto de Souza <jose.souza@intel.com>

To make life easier in the future let's pass the old crtc state
to skylake_scaler_disable() just like we already do for
for its ancestor ironlake_pfit_disable().

Cc: José Roberto de Souza <jose.souza@intel.com>
Cc: Manasi Navare <manasi.d.navare@intel.com>
Signed-off-by: NVille Syrjälä <ville.syrjala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20191213195217.15168-3-ville.syrjala@linux.intel.comReviewed-by: NJosé Roberto de Souza <jose.souza@intel.com>

HSW+ platforms call encoder .post_disable() and .post_pll_disable()
back to back. And since we don't even disable the PLL in between
let's just move everything into .post_disable().

intel_dp_mst does forward the .post_disable() call to intel_ddi at
the very end of its own .post_disable() hook, so this time MST
I shouldn't even break MST by accident.

Cc: José Roberto de Souza <jose.souza@intel.com>
Cc: Manasi Navare <manasi.d.navare@intel.com>
Signed-off-by: NVille Syrjälä <ville.syrjala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20191213195217.15168-2-ville.syrjala@linux.intel.comReviewed-by: NJosé Roberto de Souza <jose.souza@intel.com>

Remove the pointless vfunc detour for hsw_fdi_link_train()
and just call it directly. Also pass the encoder in so we
can nuke the silly encoder loop within.

Cc: José Roberto de Souza <jose.souza@intel.com>
Cc: Manasi Navare <manasi.d.navare@intel.com>
Signed-off-by: NVille Syrjälä <ville.syrjala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20191213195217.15168-1-ville.syrjala@linux.intel.comReviewed-by: NJosé Roberto de Souza <jose.souza@intel.com>

For the sake of symmetry with the crtc stuff let's add
a helper to reset the plane state to sane default values.
For the moment this only gets caller from the plane init.
Signed-off-by: NVille Syrjälä <ville.syrjala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20191107142417.11107-5-ville.syrjala@linux.intel.comReviewed-by: NJosé Roberto de Souza <jose.souza@intel.com>

We have a few places where we want to reset a crtc state to its
default values. Let's add a helper for that. We'll need the new
__drm_atomic_helper_crtc_state_reset() helper for this to allow
us to just reset the state itself without clobbering the
crtc->state pointer.

And while at it let's zero out the whole thing, except a few
choice member which we'll mark as "invalid". And thanks to this
we can now nuke intel_crtc_init_scalers().
Signed-off-by: NVille Syrjälä <ville.syrjala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20191107142417.11107-4-ville.syrjala@linux.intel.comReviewed-by: NJosé Roberto de Souza <jose.souza@intel.com>

We already have alloc/free helpers for planes, add the same for
crtcs. The main benefit is we get to move all the annoying state
initialization out of the main crtc_init() flow.
Signed-off-by: NVille Syrjälä <ville.syrjala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20191107142417.11107-3-ville.syrjala@linux.intel.comReviewed-by: NJosé Roberto de Souza <jose.souza@intel.com>

Let's get rid of the redundant intel_ prefix on our variables.
Signed-off-by: NVille Syrjälä <ville.syrjala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20191107142417.11107-2-ville.syrjala@linux.intel.comReviewed-by: NJosé Roberto de Souza <jose.souza@intel.com>

Annoyingly __drm_atomic_helper_crtc_reset() does two
totally separate things:
a) reset the state to defaults values
b) assign the crtc->state pointer

I just want a) without the b) so let's split out part
a) into __drm_atomic_helper_crtc_state_reset(). And
of course we'll do the same thing for planes and connectors.

v2: Fix conn__state vs. conn_state typo (Lucas)
    Make code and kerneldoc match for
    __drm_atomic_helper_plane_state_reset()
Signed-off-by: NVille Syrjälä <ville.syrjala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20191107142417.11107-1-ville.syrjala@linux.intel.comReviewed-by: NLucas De Marchi <lucas.demarchi@intel.com>
Reviewed-by: NDaniel Vetter <daniel.vetter@ffwll.ch>
Acked-by: NDaniel Vetter <daniel.vetter@ffwll.ch>

For very light workloads that frequently park, acquiring the display
power well (required to prevent the dmc from trashing the system) takes
longer than the execution. A good example is the igt_coherency selftest,
which is slowed down by an order of magnitude in the worst case with
powerwell cycling. To prevent frequent cycling, while keeping our fast
soft-rc6, use a timer to delay release of the display powerwell.

Fixes: 31177017 ("drm/i915/gt: Schedule request retirement when timeline idles")
References: https://gitlab.freedesktop.org/drm/intel/issues/848Signed-off-by: NChris Wilson <chris@chris-wilson.co.uk>
Cc: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
Reviewed-by: NTvrtko Ursulin <tvrtko.ursulin@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20191218093504.3477048-1-chris@chris-wilson.co.uk

Since obj->frontbuffer is no longer protected by the struct_mutex, as we
are processing the execbuf, it may be removed. Mark the
intel_frontbuffer as rcu protected, and so acquire a reference to
the struct as we track activity upon it.

Closes: https://gitlab.freedesktop.org/drm/intel/issues/827
Fixes: 8e7cb179 ("drm/i915: Extract intel_frontbuffer active tracking")
Signed-off-by: NChris Wilson <chris@chris-wilson.co.uk>
Cc: Matthew Auld <matthew.auld@intel.com>
Cc: <stable@vger.kernel.org> # v5.4+
Reviewed-by: NJoonas Lahtinen <joonas.lahtinen@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20191218104043.3539458-1-chris@chris-wilson.co.uk

If the whole GT is asleep, we know that each engine must also be asleep
and so we can quickly return without checking them all.
Signed-off-by: NChris Wilson <chris@chris-wilson.co.uk>
Cc: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
Reviewed-by: NTvrtko Ursulin <tvrtko.ursulin@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20191218000756.3475668-1-chris@chris-wilson.co.uk

If we inherit an error along the fence chain, we skip the main work
callback and go straight to the error. In the case of the vma bind
worker, we only dropped the pinned pages from the worker.

In the process, make sure we call the release earlier rather than wait
until the final reference to the fence is dropped (as a reference is
kept while being listened upon).
Signed-off-by: NChris Wilson <chris@chris-wilson.co.uk>
Reviewed-by: NJoonas Lahtinen <joonas.lahtinen@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20191216161717.2688274-1-chris@chris-wilson.co.uk

The Gen11+ and the legacy function differ in the register and value
written to interrupt the GuC. However, while on older gen the value
matches a bit on the register, on Gen11+ the value is a SW defined
payload that is sent to the FW. Since the FW behaves the same no matter
what value we pass to it, we can just write the same thing on all gens
and get rid of the function pointer by saving the register offset.
Signed-off-by: NDaniele Ceraolo Spurio <daniele.ceraolospurio@intel.com>
Cc: Michal Wajdeczko <michal.wajdeczko@intel.com>
Cc: John Harrison <John.C.Harrison@Intel.com>
Cc: Matthew Brost <matthew.brost@intel.com>
Reviewed-by: NMichal Wajdeczko <michal.wajdeczko@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20191217012316.13271-6-daniele.ceraolospurio@intel.com

Since we started using CT buffers on all gens, the function pointers can
only be set to either the _nop() or the _ct() functions. Since the
_nop() case applies to when the CT are disabled, we can just handle that
case in the _ct() functions and call them directly.

v2: keep intel_guc_send() and make the CT send/receive functions work on
    intel_guc_ct. (Michal)
Signed-off-by: NDaniele Ceraolo Spurio <daniele.ceraolospurio@intel.com>
Cc: Michal Wajdeczko <michal.wajdeczko@intel.com>
Cc: John Harrison <John.C.Harrison@Intel.com>
Cc: Matthew Brost <matthew.brost@intel.com>
Reviewed-by: NMichal Wajdeczko <michal.wajdeczko@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20191217012316.13271-5-daniele.ceraolospurio@intel.com

For better isolation of the request tracking from the rest of the
CT-related data.

v2: split to separate patch, move next_fence to substructure (Michal)
Signed-off-by: NDaniele Ceraolo Spurio <daniele.ceraolospurio@intel.com>
Cc: Michal Wajdeczko <michal.wajdeczko@intel.com>
Cc: John Harrison <John.C.Harrison@Intel.com>
Cc: Matthew Brost <matthew.brost@intel.com>
Reviewed-by: NMichal Wajdeczko <michal.wajdeczko@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20191217012316.13271-4-daniele.ceraolospurio@intel.com

The GuC supports having multiple CT buffer pairs and we designed our
implementation with that in mind. However, the different channels are not
processed in parallel within the GuC, so there is very little advantage
in having multiple channels (independent locks?), compared to the
drawbacks (one channel can starve the other if messages keep being
submitted to it). Given this, it is unlikely we'll ever add a second
channel and therefore we can simplify our code by removing the
flexibility.

v2: split substructure grouping to separate patch, improve docs (Michal)
Signed-off-by: NDaniele Ceraolo Spurio <daniele.ceraolospurio@intel.com>
Cc: Michal Wajdeczko <michal.wajdeczko@intel.com>
Cc: John Harrison <John.C.Harrison@Intel.com>
Cc: Matthew Brost <matthew.brost@intel.com>
Reviewed-by: NMichal Wajdeczko <michal.wajdeczko@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20191217012316.13271-3-daniele.ceraolospurio@intel.com

We track the status of the GuC much more closely now and we expect the
enable/disable functions to be correctly called only once. If this isn't
true we do want to flag it as a flow failure (via the BUG_ON in the ctch
functions) and not silently ignore the call.
Suggested-by: NMichal Wajdeczko <michal.wajdeczko@intel.com>
Signed-off-by: NDaniele Ceraolo Spurio <daniele.ceraolospurio@intel.com>
Reviewed-by: NMichal Wajdeczko <michal.wajdeczko@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20191217012316.13271-2-daniele.ceraolospurio@intel.com