Now that we pass along the expected interruptible nature for the
wait-for-idle, we do not need to modify the global
i915->mm.interruptible for this single call. (Only the immediate call to
i915_gem_wait_for_idle() takes the interruptible status as the other
action, dma_map_sg(), is independent of i915.ko)
Signed-off-by: NChris Wilson <chris@chris-wilson.co.uk>
Reviewed-by: NJoonas Lahtinen <joonas.lahtinen@linux.intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/1470388464-28458-7-git-send-email-chris@chris-wilson.co.uk

The principal motivation for this was to try and eliminate the
struct_mutex from i915_gem_suspend - but we still need to hold the mutex
current for the i915_gem_context_lost(). (The issue there is that there
may be an indirect lockdep cycle between cpu_hotplug (i.e. suspend) and
struct_mutex via the stop_machine().) For the moment, enabling last
request tracking for the engine, allows us to do busyness checking and
waiting without requiring the struct_mutex - which is useful in its own
right.

As a side-effect of having a robust means for tracking engine busyness,
we can replace our other busyness heuristic, that of comparing against
the last submitted seqno. For paranoid reasons, we have a semi-ordered
check of that seqno inside the hangchecker, which we can now improve to
an ordered check of the engine's busyness (removing a locked xchg in the
process).

v2: Pass along "bool interruptible" as being unlocked we cannot rely on
i915->mm.interruptible being stable or even under our control.
v3: Replace check Ironlake i915_gpu_busy() with the common precalculated value
Signed-off-by: NChris Wilson <chris@chris-wilson.co.uk>
Reviewed-by: NJoonas Lahtinen <joonas.lahtinen@linux.intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/1470388464-28458-6-git-send-email-chris@chris-wilson.co.uk

Before suspending (or unloading), we would first wait upon all rendering
to be completed and then disable the rings. This later step is a remanent
from DRI1 days when we did not use request tracking for all operations
upon the ring. Now that we are sure we are waiting upon the very last
operation by the engine, we can forgo clobbering the ring registers,
though we do keep the assert that the engine is indeed idle before
sleeping.
Signed-off-by: NChris Wilson <chris@chris-wilson.co.uk>
Reviewed-by: NJoonas Lahtinen <joonas.lahtinen@linux.intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/1470388464-28458-5-git-send-email-chris@chris-wilson.co.uk

Inside the kthread context, we can't be interrupted by signals so
touching the mm.interruptible flag is pointless and wait-request now
consumes EIO itself.
Signed-off-by: NChris Wilson <chris@chris-wilson.co.uk>
Reviewed-by: NJoonas Lahtinen <joonas.lahtinen@linux.intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/1470388464-28458-4-git-send-email-chris@chris-wilson.co.uk

We can completely avoid taking the struct_mutex around the non-blocking
waits by switching over to the RCU request management (trading the mutex
for a RCU read lock and some complex atomic operations). The improvement
is that we gain further contention reduction, and overall the code
become simpler due to the reduced mutex dancing.
Signed-off-by: NChris Wilson <chris@chris-wilson.co.uk>
Reviewed-by: NJoonas Lahtinen <joonas.lahtinen@linux.intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/1470388464-28458-3-git-send-email-chris@chris-wilson.co.uk

We can completely avoid taking the struct_mutex around the non-blocking
waits by switching over to the RCU request management (trading the mutex
for a RCU read lock and some complex atomic operations). The improvement
is that we gain further contention reduction, and overall the code
become simpler due to the reduced mutex dancing.

v2: Move i915_gem_fault tracepoint back to the start of the function,
before the unlocked wait.
Signed-off-by: NChris Wilson <chris@chris-wilson.co.uk>
Reviewed-by: NJoonas Lahtinen <joonas.lahtinen@linux.intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/1470388464-28458-2-git-send-email-chris@chris-wilson.co.uk

It is useful to be able to wait on pending rendering without grabbing
the struct_mutex. We can do this by using the i915_gem_active_get_rcu()
primitive to acquire a reference to the pending request without
requiring struct_mutex, just the RCU read lock, and then call
i915_wait_request().

v2: Rebase onto new i915_gem_active_get_unlocked() semantics that take
the RCU read lock on behalf of the caller.
Signed-off-by: NChris Wilson <chris@chris-wilson.co.uk>
Reviewed-by: NJoonas Lahtinen <joonas.lahtinen@linux.intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/1470388464-28458-1-git-send-email-chris@chris-wilson.co.uk

Backmerge the 4.8 pull request state from Dave - conflicts were
getting out of hand, and Chris has some patches which outright don't
apply without everything merged together again.
Signed-off-by: NDaniel Vetter <daniel.vetter@intel.com>

The spec was recently fixed to have the correct iboost setting for the
SKL Y/U DP DDI buffer translation table entry 2. Update our tables
to match.

Cc: David Weinehall <david.weinehall@linux.intel.com>
Signed-off-by: NVille Syrjälä <ville.syrjala@linux.intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/1470140517-13011-1-git-send-email-ville.syrjala@linux.intel.com
Cc: stable@vger.kernel.org
Reviewed-by: NDavid Weinehall <david.weinehall@linux.intel.com>

The bspec was updated a couple weeks ago to add an extra block per line
to plane watermark calculations for linear pixel formats.

Bspec update 115327 description:
  "Gen9+ - Updated the plane blocks per line calculation for linear
  cases. Adds +1 for all linear cases to handle the non-block aligned
  stride cases."

Cc: Lyude <cpaul@redhat.com>
Cc: drm-intel-fixes@lists.freedesktop.org
Signed-off-by: NMatt Roper <matthew.d.roper@intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/1470344880-27394-1-git-send-email-matthew.d.roper@intel.comReviewed-by: NLyude <cpaul@redhat.com>

If the GEM objects being rendered with in this request have been
exported via dma-buf to a third party, hook ourselves into the dma-buf
reservation object so that the third party can serialise with our
rendering via the dma-buf fences.

Testcase: igt/prime_busy
Signed-off-by: NChris Wilson <chris@chris-wilson.co.uk>
Reviewed-by: NDaniel Vetter <daniel.vetter@ffwll.ch>
Link: http://patchwork.freedesktop.org/patch/msgid/1470324762-2545-26-git-send-email-chris@chris-wilson.co.uk

If we enable RCU for the requests (providing a grace period where we can
inspect a "dead" request before it is freed), we can allow callers to
carefully perform lockless lookup of an active request.

However, by enabling deferred freeing of requests, we can potentially
hog a lot of memory when dealing with tens of thousands of requests per
second - with a quick insertion of a synchronize_rcu() inside our
shrinker callback, that issue disappears.

v2: Currently, it is our responsibility to handle reclaim i.e. to avoid
hogging memory with the delayed slab frees. At the moment, we wait for a
grace period in the shrinker, and block for all RCU callbacks on oom.
Suggested alternatives focus on flushing our RCU callback when we have a
certain number of outstanding request frees, and blocking on that flush
after a second high watermark. (So rather than wait for the system to
run out of memory, we stop issuing requests - both are nondeterministic.)

Paul E. McKenney wrote:

Another approach is synchronize_rcu() after some largish number of
requests.  The advantage of this approach is that it throttles the
production of callbacks at the source.  The corresponding disadvantage
is that it slows things up.

Another approach is to use call_rcu(), but if the previous call_rcu()
is still in flight, block waiting for it.  Yet another approach is
the get_state_synchronize_rcu() / cond_synchronize_rcu() pair.  The
idea is to do something like this:

        cond_synchronize_rcu(cookie);
        cookie = get_state_synchronize_rcu();

You would of course do an initial get_state_synchronize_rcu() to
get things going.  This would not block unless there was less than
one grace period's worth of time between invocations.  But this
assumes a busy system, where there is almost always a grace period
in flight.  But you can make that happen as follows:

        cond_synchronize_rcu(cookie);
        cookie = get_state_synchronize_rcu();
        call_rcu(&my_rcu_head, noop_function);

Note that you need additional code to make sure that the old callback
has completed before doing a new one.  Setting and clearing a flag
with appropriate memory ordering control suffices (e.g,. smp_load_acquire()
and smp_store_release()).

v3: More comments on compiler and processor order of operations within
the RCU lookup and discover we can use rcu_access_pointer() here instead.

v4: Wrap i915_gem_active_get_rcu() to take the rcu_read_lock itself.
Signed-off-by: NChris Wilson <chris@chris-wilson.co.uk>
Cc: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>
Cc: "Goel, Akash" <akash.goel@intel.com>
Cc: Josh Triplett <josh@joshtriplett.org>
Cc: Daniel Vetter <daniel.vetter@ffwll.ch>
Reviewed-by: NDaniel Vetter <daniel.vetter@ffwll.ch>
Link: http://patchwork.freedesktop.org/patch/msgid/1470324762-2545-25-git-send-email-chris@chris-wilson.co.uk

Just move it earlier so that we can use the companion nonblocking
version in a couple of more callsites without having to add a forward
declaration.
Signed-off-by: NChris Wilson <chris@chris-wilson.co.uk>
Reviewed-by: NJoonas Lahtinen <joonas.lahtinen@linux.intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/1470324762-2545-24-git-send-email-chris@chris-wilson.co.uk

We are motivated to avoid using a bitfield for obj->active for a couple
of reasons. Firstly, we wish to document our lockless read of obj->active
using READ_ONCE inside i915_gem_busy_ioctl() and that requires an
integral type (i.e. not a bitfield). Secondly, gcc produces abysmal code
when presented with a bitfield and that shows up high on the profiles of
request tracking (mainly due to excess memory traffic as it converts
the bitfield to a register and back and generates frequent AGI in the
process).

v2: BIT, break up a long line in compute the other engines, new paint
for i915_gem_object_is_active (now i915_gem_object_get_active).
Signed-off-by: NChris Wilson <chris@chris-wilson.co.uk>
Reviewed-by: NJoonas Lahtinen <joonas.lahtinen@linux.intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/1470324762-2545-23-git-send-email-chris@chris-wilson.co.uk

Rather than a mismash of struct drm_device *dev and struct
drm_i915_private *dev_priv being used freely within a function, be
consistent and only pass along dev_priv.
Signed-off-by: NChris Wilson <chris@chris-wilson.co.uk>
Reviewed-by: NDaniel Vetter <daniel.vetter@ffwll.ch>
Reviewed-by: NJoonas Lahtinen <joonas.lahtinen@linux.intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/1470324762-2545-22-git-send-email-chris@chris-wilson.co.uk

The individual bits inside obj->frontbuffer_bits are protected by each
plane->mutex, but the whole bitfield may be accessed by multiple KMS
operations simultaneously and so the RMW need to be under atomics.
However, for updating the single field we do not need to mandate that it
be under the struct_mutex, one more step towards its removal as the de
facto BKL.
Signed-off-by: NChris Wilson <chris@chris-wilson.co.uk>
Cc: Daniel Vetter <daniel.vetter@ffwll.ch>
Reviewed-by: NJoonas Lahtinen <joonas.lahtinen@linux.intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/1470324762-2545-21-git-send-email-chris@chris-wilson.co.uk

We only need a very lightweight mechanism here as the locking is only
used for co-ordinating a bitfield.

v2: Move the cheap unlikely tests into the caller
v3: Move the kerneldoc into the header (now separated out into
intel_fronbuffer.h for better kerneldoc and readability)
Signed-off-by: NChris Wilson <chris@chris-wilson.co.uk>
Reviewed-by: NJoonas Lahtien <joonas.lahtinen@linux.intel.com>
Cc: Daniel Vetter <daniel.vetter@ffwll.ch>
Reviewed-by: NDaniel Vetter <daniel.vetter@ffwll.ch>
Link: http://patchwork.freedesktop.org/patch/msgid/1470324762-2545-20-git-send-email-chris@chris-wilson.co.uk

In view of adding inline functions into the intel_frontbuffer section,
we first split the header into its own file so that we can integrate it
more easily with kerneldoc.
Signed-off-by: NChris Wilson <chris@chris-wilson.co.uk>
Cc: Daniel Vetter <daniel.vetter@ffwll.ch>
Reviewed-by: NDaniel Vetter <daniel.vetter@ffwll.ch>
Link: http://patchwork.freedesktop.org/patch/msgid/1470324762-2545-19-git-send-email-chris@chris-wilson.co.uk

Since i915_gem_obj_ggtt_pin() is an idiom breaking curry function for
i915_gem_object_ggtt_pin(), spare us the confusion and remove it.
Removing it now simplifies later patches to change the i915_vma_pin()
(and friends) interface.

v2: Add a redundant GEM_BUG_ON(!view) to
i915_gem_obj_lookup_or_create_ggtt_vma()
Signed-off-by: NChris Wilson <chris@chris-wilson.co.uk>
Reviewed-by: NJoonas Lahtinen <joonas.lahtinen@linux.intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/1470324762-2545-18-git-send-email-chris@chris-wilson.co.uk

Not only is i915_vma_pin() called for every single object on every single
execbuf, it is usually a simple increment as the VMA is already bound for
execution by the GPU. Rearrange the tests for unbound and pin_count
overflow so that we can do the increment and test very cheaply and
compact enough to inline the operation into execbuf. The trick used is
to note that we can check for an overflow bit (keeping space available
for it inside the flags) at the same time as checking the binding bits.
Signed-off-by: NChris Wilson <chris@chris-wilson.co.uk>
Reviewed-by: NJoonas Lahtinen <joonas.lahtinen@linux.intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/1470324762-2545-17-git-send-email-chris@chris-wilson.co.uk

In preparation to perform some magic to speed up i915_vma_pin(), which
is among the hottest of hot paths in execbuf, refactor all the bitfields
accessed by i915_vma_pin() into a single unified set of flags.
Signed-off-by: NChris Wilson <chris@chris-wilson.co.uk>
Reviewed-by: NJoonas Lahtinen <joonas.lahtinen@linux.intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/1470324762-2545-16-git-send-email-chris@chris-wilson.co.uk

During execbuffer we look up the i915_vma in order to reserve them in
the VM. However, we then do a double lookup of the vma in order to then
pin them, all because we lack the necessary interfaces to operate on
i915_vma - so introduce i915_vma_pin()!

v2: Tidy parameter lists to remove one level of redirection in the hot
path.
Signed-off-by: NChris Wilson <chris@chris-wilson.co.uk>
Cc: Mika Kuoppala <mika.kuoppala@intel.com>
Reviewed-by: NJoonas Lahtinen <joonas.lahtinen@linux.intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/1470324762-2545-15-git-send-email-chris@chris-wilson.co.uk

In the next few patches, the VMA pinning API is overhauled and to reduce
the churn we pull out the update to the accessors into a prep patch.
Signed-off-by: NChris Wilson <chris@chris-wilson.co.uk>
Reviewed-by: NJoonas Lahtinen <joonas.lahtinen@linux.intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/1470324762-2545-14-git-send-email-chris@chris-wilson.co.uk

Tracking the size of the VMA as allocated allows us to dramatically
reduce the complexity of later functions (like inserting the VMA in to
the drm_mm range manager).
Signed-off-by: NChris Wilson <chris@chris-wilson.co.uk>
Reviewed-by: NJoonas Lahtinen <joonas.lahtinen@linux.intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/1470324762-2545-13-git-send-email-chris@chris-wilson.co.uk

For consistency, internal functions should take drm_i915_private rather
than drm_device. Now that we are subclassing drm_device, there are no
more size wins, but being consistent is its own blessing.
Signed-off-by: NChris Wilson <chris@chris-wilson.co.uk>
Reviewed-by: NJoonas Lahtinen <joonas.lahtinen@linux.intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/1470324762-2545-12-git-send-email-chris@chris-wilson.co.uk

In order to be consistent with other address space functions, we want to
pass around 64-bit sizes, even though all known global GTT are limited
to 4GiB. Similarly, we are trying to be consistent in using the _ggtt_
nomenclature when referring to the special global GTT.

v2: Update docs to consistently state "global GTT".
Signed-off-by: NChris Wilson <chris@chris-wilson.co.uk>
Reviewed-by: NJoonas Lahtinen <joonas.lahtinen@linux.intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/1470324762-2545-11-git-send-email-chris@chris-wilson.co.uk

As we always allocate in chunks of 4096 (that being both the PAGE_SIZE
and our own GTT_PAGE_SIZE), we know that all results from the drm_mm are
aligned to at least 4096. The drm_mm allocator itself is optimised for
alignment == 0, and so by converting alignments of 4096 to 0 we can
satisfy our own requirements and still hit the faster path.
Signed-off-by: NChris Wilson <chris@chris-wilson.co.uk>
Cc: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>
Reviewed-by: NJoonas Lahtinen <joonas.lahtinen@linux.intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/1470324762-2545-10-git-send-email-chris@chris-wilson.co.uk

Split the insertion into the address space's range manager and binding
of that object into the GTT to simplify the code flow when pinning a
VMA.
Signed-off-by: NChris Wilson <chris@chris-wilson.co.uk>
Reviewed-by: NJoonas Lahtinen <joonas.lahtinen@linux.intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/1470324762-2545-9-git-send-email-chris@chris-wilson.co.uk

i915_gem_valid_gtt_space() is used after inserting the VMA to double
check the list - the location should have been chosen to pass all the
restrictions.
Signed-off-by: NChris Wilson <chris@chris-wilson.co.uk>
Reviewed-by: NJoonas Lahtinen <joonas.lahtinen@linux.intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/1470324762-2545-8-git-send-email-chris@chris-wilson.co.uk

Our GPUs impose certain requirements upon buffers that depend upon how
exactly they are used. Typically this is expressed as that they require
a larger surface than would be naively computed by pitch * height.
Normally such requirements are hidden away in the userspace driver, but
when we accept pointers from strangers and later impose extra conditions
on them, the original client allocator has no idea about the
monstrosities in the GPU and we require the userspace driver to inform
the kernel how many padding pages are required beyond the client
allocation.

v2: Long time, no see
v3: Try an anonymous union for uapi struct compatibility
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: http://patchwork.freedesktop.org/patch/msgid/1470324762-2545-7-git-send-email-chris@chris-wilson.co.uk

This is not the full fix, as we are required to percolate the u64 nature
down through the drm_mm stack, but this is required now to prevent
explosions due to mismatch between execbuf (eb_vma_misplaced) and vma
binding (i915_vma_misplaced) - and reduces the risk of spurious changes
as we adjust the vma interface in the next patches.

v2: long long casts not required for u64 printk (%llx)
Signed-off-by: NChris Wilson <chris@chris-wilson.co.uk>
Reviewed-by: NJoonas Lahtinen <joonas.lahtinen@linux.intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/1470324762-2545-6-git-send-email-chris@chris-wilson.co.uk

Move the single line to the callsite as the name is now misleading, and
the purpose is solely to add the request to the execution queue. Here,
we can see that if we failed to dispatch the batch from the request, we
can forgo flushing the GPU when closing the request.
Signed-off-by: NChris Wilson <chris@chris-wilson.co.uk>
Reviewed-by: NJoonas Lahtinen <joonas.lahtinen@linux.intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/1470324762-2545-5-git-send-email-chris@chris-wilson.co.uk

This reimplements the denial-of-service protection against igt from
commit 227f782e ("drm/i915: Retire requests before creating a new
one") and transfers the stall from before each batch into get_pages().
The issue is that the stall is increasing latency between batches which
is detrimental in some cases (especially coupled with execlists) to
keeping the GPU well fed. Also we have made the observation that retiring
requests can of itself free objects (and requests) and therefore makes
a good first step when shrinking.

v2: Recycle objects prior to i915_gem_object_get_pages()
v3: Remove the reference to the ring from i915_gem_requests_ring() as it
operates on an intel_engine_cs.
v4: Since commit 9b5f4e5e ("drm/i915: Retire oldest completed request
before allocating next") we no longer need the safeguard to retire
requests before get_pages(). We no longer see the huge latencies when
hitting the shrinker between allocations.
Signed-off-by: NChris Wilson <chris@chris-wilson.co.uk>
Cc: Daniel Vetter <daniel@ffwll.ch>
Cc: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>
Reviewed-by: NJoonas Lahtinen <joonas.lahtinen@linux.intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/1470324762-2545-4-git-send-email-chris@chris-wilson.co.uk

We should not rely on obj->active being uptodate unless we manually
flush it. Instead, we can verify that the next available batch object is
idle by looking at its last active request (and checking it for
completion).

v2: remove the struct drm_device forward declaration added in the
process of removing its necessity
Signed-off-by: NChris Wilson <chris@chris-wilson.co.uk>
Reviewed-by: NJoonas Lahtinen <joonas.lahtinen@linux.intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/1470324762-2545-3-git-send-email-chris@chris-wilson.co.uk

Eviction is VM local, so we can ignore the significance of the
drm_device in the caller, and leave it to i915_gem_evict_something() to
manage itself.
Signed-off-by: NChris Wilson <chris@chris-wilson.co.uk>
Reviewed-by: NJoonas Lahtinen <joonas.lahtinen@linux.intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/1470324762-2545-2-git-send-email-chris@chris-wilson.co.uk

Slight micro-optimise to produce combine loops so that gcc is able to
optimise the inner-loops concisely. Since we are reviewing the loops, we
can update the comments to describe the current state of affairs, in
particular the distinction between evicting from the global GTT (which
may contain untracked items and transient global pins) and the
per-process GTT.
Signed-off-by: NChris Wilson <chris@chris-wilson.co.uk>
Reviewed-by: NJoonas Lahtinen <joonas.lahtinen@linux.intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/1470324762-2545-1-git-send-email-chris@chris-wilson.co.uk

On Haswell/Broadwell, the HD-Audio block is inside the HDMI/display
power well and so the sna-hda audio codec acquires the display power
well while it is operational. However, Skylake separates the powerwells
again, but yet we still need the audio powerwell to setup the registers.
(But then the hardware uses those registers even while powered off???)

Acquiring the powerwell around setting the chicken bits when setting up
the audio channel does at least silence the WARNs from touching our
registers whilst unpowered. We silence our own test cases, but maybe
there is a latent bug in using the audio channel?

v2: Grab both rpm wakelock and audio wakelock

Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=96214
Fixes: 03b135ce "ALSA: hda - remove dependency on i915 power well for SKL")
Signed-off-by: NChris Wilson <chris@chris-wilson.co.uk>
Cc: Libin Yang <libin.yang@intel.com>
Cc: Takashi Iwai <tiwai@suse.de>
Cc: Marius Vlad <marius.c.vlad@intel.com>
Tested-by: NHans de Goede <hdegoede@redhat.com>
Cc: stable@vger.kernel.org
Link: http://patchwork.freedesktop.org/patch/msgid/1470240540-29004-1-git-send-email-chris@chris-wilson.co.ukReviewed-by: NDaniel Vetter <daniel.vetter@ffwll.ch>

My ASUS PB278 at least doesn't seem to appreciate when you try to
ack sink irqs when there are none. Results in this sort of dmesg spam
[drm:drm_dp_dpcd_access] too many retries, giving up

Let's skip the ack if there are no pending irqs. I have no clue why we
do this in two places. One of them likely should just go away. Oh, and
MST has its own sink irq handler too...
Signed-off-by: NVille Syrjälä <ville.syrjala@linux.intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/1469717448-4297-12-git-send-email-ville.syrjala@linux.intel.comReviewed-by: NDaniel Vetter <daniel.vetter@ffwll.ch>

No need to iterate the rates array in intel_dp_max_link_rate(). We know
the max rate will be the last entry, and we already know the size.

Cc: Ander Conselvan de Oliveira <ander.conselvan.de.oliveira@intel.com>
Cc: Jim Bride <jim.bride@linux.intel.com>
Cc: Manasi D Navare <manasi.d.navare@intel.com>
Cc: Durgadoss R <durgadoss.r@intel.com>
Signed-off-by: NVille Syrjälä <ville.syrjala@linux.intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/1469717448-4297-10-git-send-email-ville.syrjala@linux.intel.comReviewed-by: NDaniel Vetter <daniel.vetter@ffwll.ch>

With HSW + Dell UP2414Q (at least) drm_probe_ddc() occasionally fails,
and then we'll assume that the entire display has been disconnected.
We don't need the EDID from the main link, so we can simply check if
the sink is MST capable, and if so treat is as connected.

v2: Skip drm_probe_ddc() entirely for MST (Daniel)

Cc: Ander Conselvan de Oliveira <ander.conselvan.de.oliveira@intel.com>
Cc: Jim Bride <jim.bride@linux.intel.com>
Cc: Manasi D Navare <manasi.d.navare@intel.com>
Cc: Durgadoss R <durgadoss.r@intel.com>
Signed-off-by: NVille Syrjälä <ville.syrjala@linux.intel.com>
Reviewed-by: NDaniel Vetter <daniel.vetter@ffwll.ch>
Link: http://patchwork.freedesktop.org/patch/msgid/1469800276-6979-1-git-send-email-ville.syrjala@linux.intel.com