If we only call process_csb() from the tasklet, though we lose the
ability to bypass ksoftirqd interrupt processing on direct submission
paths, we can push it out of the irq-off spinlock.
The penalty is that we then allow schedule_out to be called concurrently
with schedule_in requiring us to handle the usage count (baked into the
pointer itself) atomically.
As we do kick the tasklets (via local_bh_enable()) after our submission,
there is a possibility there to see if we can pull the local softirq
processing back from the ksoftirqd.
v2: Store the 'switch_priority_hint' on submission, so that we can
safely check during process_csb().
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Mika Kuoppala <mika.kuoppala@linux.intel.com>
Reviewed-by: Mika Kuoppala <mika.kuoppala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20190816171608.11760-1-chris@chris-wilson.co.uk
As every i915_active_request should be serialised by a dedicated lock,
i915_active consists of a tree of locks; one for each node. Markup up
the i915_active_request with what lock is supposed to be guarding it so
that we can verify that the serialised updated are indeed serialised.
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Reviewed-by: Mika Kuoppala <mika.kuoppala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20190816121000.8507-2-chris@chris-wilson.co.uk
We use timeline->mutex to protect modifications to
context->active_count, and the associated enable/disable callbacks.
Due to complications with engine-pm barrier there is a path where we used
a "superlock" to provide serialised protect and so could not
unconditionally assert with lockdep that it was always held. However,
we can mark the mutex as taken (noting that we may be nested underneath
ourselves) which means we can be reassured the right timeline->mutex is
always treated as held and let lockdep roam free.
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
Reviewed-by: Mika Kuoppala <mika.kuoppala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20190816121000.8507-1-chris@chris-wilson.co.uk
All WOPCM error messages are device specific, so use
device specific error functions.
Signed-off-by: Michal Wajdeczko <michal.wajdeczko@intel.com>
Cc: Chris Wilson <chris@chris-wilson.co.uk>
Reviewed-by: Chris Wilson <chris@chris-wilson.co.uk>
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Link: https://patchwork.freedesktop.org/patch/msgid/20190816105501.31020-5-michal.wajdeczko@intel.com
If WOPCM layout is already locked in HW we shouldn't continue
with our own partitioning as it could be likely different and
we will be unable to enforce it and fail. Instead we should try
to reuse what is already programmed, maybe there will be a fit.
This should enable us to reload driver with slightly different
HuC firmware (or even without HuC) without need to reboot.
v2: reordered/rebased
Signed-off-by: Michal Wajdeczko <michal.wajdeczko@intel.com>
Cc: Daniele Ceraolo Spurio <daniele.ceraolospurio@intel.com>
Cc: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Michal Winiarski <michal.winiarski@intel.com>
Reviewed-by: Daniele Ceraolo Spurio <daniele.ceraolospurio@intel.com>
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Link: https://patchwork.freedesktop.org/patch/msgid/20190816105501.31020-4-michal.wajdeczko@intel.com
We can do WOPCM partitioning using rough estimates and limits
and perform detailed check as separate step.
v2: oops! s/max/min
v3: consolidate overflow checks (Daniele)
Signed-off-by: Michal Wajdeczko <michal.wajdeczko@intel.com>
Cc: Daniele Ceraolo Spurio <daniele.ceraolospurio@intel.com>
Cc: Chris Wilson <chris@chris-wilson.co.uk>
Reviewed-by: Chris Wilson <chris@chris-wilson.co.uk>
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Link: https://patchwork.freedesktop.org/patch/msgid/20190816105501.31020-3-michal.wajdeczko@intel.com
While we need to know WOPCM size to do this sanity check, it has more to
do with FW than with WOPCM. Let's move the check to fetch phase, it's
not like WOPCM is going to grow in the meantime.
v2: rebased
v3: use __intel_uc_fw_get_upload_size (Daniele)
Signed-off-by: Michał Winiarski <michal.winiarski@intel.com>
Signed-off-by: Michal Wajdeczko <michal.wajdeczko@intel.com>
Cc: Daniele Ceraolo Spurio <daniele.ceraolospurio@intel.com>
Cc: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Jackie Li <yaodong.li@intel.com>
Cc: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>
Reviewed-by: Daniele Ceraolo Spurio <daniele.ceraolospurio@intel.com>
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Link: https://patchwork.freedesktop.org/patch/msgid/20190816105501.31020-2-michal.wajdeczko@intel.com
Since nodes are cached in a free-list, and potentially marked as free
without actually being destroyed, thus allowing them to be
opportunistically re-allocated, we should apply kmemleak_update_trace
every time a node is given a new owner and marked as allocated, to aid
in debugging.
Suggested-by: Chris Wilson <chris@chris-wilson.co.uk>
Signed-off-by: Matthew Auld <matthew.auld@intel.com>
Cc: Chris Wilson <chris@chris-wilson.co.uk>
Reviewed-by: Chris Wilson <chris@chris-wilson.co.uk>
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Link: https://patchwork.freedesktop.org/patch/msgid/20190816105357.14340-2-matthew.auld@intel.com
If we are leaking nodes don't hide it. Also stop trying to be
"defensive" and instead embrace Kasan et al.
Signed-off-by: Matthew Auld <matthew.auld@intel.com>
Cc: Chris Wilson <chris@chris-wilson.co.uk>
Reviewed-by: Chris Wilson <chris@chris-wilson.co.uk>
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Link: https://patchwork.freedesktop.org/patch/msgid/20190816105357.14340-1-matthew.auld@intel.com
Move the active tracking for the frontbuffer operations out of the
i915_gem_object and into its own first class (refcounted) object. In the
process of detangling, we switch from low level request tracking to the
easier i915_active -- with the plan that this avoids any potential
atomic callbacks as the frontbuffer tracking wishes to sleep as it
flushes.
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Reviewed-by: Matthew Auld <matthew.auld@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20190816074635.26062-1-chris@chris-wilson.co.uk
Forgo the struct_mutex requirement for request retirement as we have
been transitioning over to only using the timeline->mutex for
controlling the lifetime of a request on that timeline.
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Reviewed-by: Matthew Auld <matthew.auld@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20190815205709.24285-4-chris@chris-wilson.co.uk
In preparation for removing struct_mutex from around context retirement,
we need to make timeline pinning and unpinning safe. Since multiple
engines/contexts can share a single timeline, we cannot rely on
borrowing the context mutex (otherwise we could state that the timeline
is only pinned/unpinned inside the context pin/unpin and so guarded by
it). However, we only perform a sequence of atomic operations inside the
timeline pin/unpin and the sequence of those operations is safe for a
concurrent unpin / pin, so we can relax the struct_mutex requirement.
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Reviewed-by: Matthew Auld <matthew.auld@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20190815205709.24285-3-chris@chris-wilson.co.uk
Since __i915_request_queue() may be called from hardirq (timer) context,
we cannot use local_bh_disable/enable at the lower level. As we do want
to kick the tasklet to speed up initial submission or preemption for
normal client submission, lift it to the normal process context
callpath.
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Reviewed-by: Mika Kuoppala <mika.kuoppala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20190815042031.27750-1-chris@chris-wilson.co.uk
Flush according to what gen11 expects when writing
breadcrumbs. As only the seqnowrite + flush differs
between engine and gens, enclose the footer to
helper.
v2: avoid problem of sane local naming by not using them
Cc: Chris Wilson <chris@chris-wilson.co.uk>
Signed-off-by: Mika Kuoppala <mika.kuoppala@linux.intel.com>
Reviewed-by: Chris Wilson <chris@chris-wilson.co.uk>
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Link: https://patchwork.freedesktop.org/patch/msgid/20190815094929.358-1-mika.kuoppala@linux.intel.com
Add tile cache flushing for gen11. To relive us from the
burden of previous obsolete workarounds, make a dedicated
flush/invalidate callback for gen11.
To fortify an independent single flush, do post
sync op as there are indications that without it
we don't flush everything. This should also make this
callback more readily usable in tgl (see l3 fabric flush).
v2: whitespacing
Cc: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Daniele Ceraolo Spurio <daniele.ceraolospurio@intel.com>
Signed-off-by: Mika Kuoppala <mika.kuoppala@linux.intel.com>
Reviewed-by: Chris Wilson <chris@chris-wilson.co.uk>
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Link: https://patchwork.freedesktop.org/patch/msgid/20190815083055.14132-1-mika.kuoppala@linux.intel.com
Dan reported the following static checker warning:
drivers/gpu/drm/i915/selftests/i915_buddy.c:670 igt_buddy_alloc_range()
error: we previously assumed 'block' could be null (see line 665)
Reported-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Matthew Auld <matthew.auld@intel.com>
Cc: Dan Carpenter <dan.carpenter@oracle.com>
Cc: Chris Wilson <chris@chris-wilson.co.uk>
Reviewed-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Link: https://patchwork.freedesktop.org/patch/msgid/20190815103210.11802-1-matthew.auld@intel.com
Looking around the GT initialisation, we have a few log messages we
think are interesting enough present to the user (such as the amount of L4
cache) and a few to inform them of the result of actions or conflicting
HW restrictions (i.e. quirks). These are device specific messages, so
use the dev family of printk.
v2: shave off a few bytes of .rodata!
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>
Cc: Michal Wajdeczko <michal.wajdeczko@intel.com>
Reviewed-by: Michal Wajdeczko <michal.wajdeczko@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20190815093604.3618-1-chris@chris-wilson.co.uk
We use the request pointer inside the i915_active_node as the indicator
of the barrier's status; we mark it as used during
i915_request_add_active_barriers(), and search for an available barrier
in reuse_idle_barrier(). That check must be carefully serialised to
ensure we do use an engine for the barrier and not just a random
pointer. (Along the other reuse path, we are fully serialised by the
timeline->mutex.) The acquisition of the barrier itself is ordered through
the strong memory barrier in llist_del_all().
Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=111397
Fixes: d8af05ff38 ("drm/i915: Allow sharing the idle-barrier from other kernel requests")
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Reviewed-by: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20190813200905.11369-1-chris@chris-wilson.co.uk
The fb_base is only used for communicating the GTT BAR from one piece of
the display code (kms setup) to another (fbdev). What is required in the
fbdev is just the aperture address which should be derived from the
bo we allocate for the framebuffer directly.
The same appears true for drm/; it is not used by the core or the uAPI,
it is merely for conveniently passing a device address from bit of
display management code to another.
v2: Note that since we only expose enough of a system map to cover our
single framebuffer, the screen_base/size and the smem are one and the
same.
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Daniel Vetter <daniel.vetter@ffwll.ch>
Cc: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>
Cc: Anusha Srivatsa <anusha.srivatsa@intel.com>
Reviewed-by: Anusha Srivatsa <anusha.srivatsa@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20190813182112.23227-1-chris@chris-wilson.co.uk
The engine->guc_id is GuC FW defined and it is not guaranteed to be
below I915_NUM_ENGINES, so we shouldn't use it with the i915-defined
client->submissions, as we might overflow.
Instead of fixing it, just get rid of client->submissions, because the
information we get from it is not interesting anymore now that we only
have 1 client.
Signed-off-by: Daniele Ceraolo Spurio <daniele.ceraolospurio@intel.com>
Cc: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Michal Wajdeczko <michal.wajdeczko@intel.com>
Reviewed-by: Chris Wilson <chris@chris-wilson.co.uk>
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Link: https://patchwork.freedesktop.org/patch/msgid/20190814002145.29056-1-daniele.ceraolospurio@intel.com
A new macro that is going to be added in a further patch will need to
adjust the offset returned by _MMIO_TRANS2(), so here adding
_TRANS2() and moving most of the implementation of _MMIO_TRANS2() to
it and while at it taking the opportunity to rename pipe to trans.
Cc: Rodrigo Vivi <rodrigo.vivi@intel.com>
Cc: Dhinakaran Pandiyan <dhinakaran.pandiya@intel.com>
Reviewed-by: Dhinakaran Pandiyan <dhinakaran.pandiya@intel.com>
Signed-off-by: José Roberto de Souza <jose.souza@intel.com>
Reviewed-by: Lucas De Marchi <lucas.demarchi@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20190730224753.14907-2-jose.souza@intel.com
Just moving it to reduce the tabs and avoid break code lines.
No behavior changes intended here.
v2:
- Reading misc display IRQ outside of gen8_de_misc_irq_handler() as
other irq handlers (Dhinakaran)
Cc: Dhinakaran Pandiyan <dhinakaran.pandiyan@intel.com>
Reviewed-by: Dhinakaran Pandiyan <dhinakaran.pandiyan@intel.com>
Reviewed-by: Rodrigo Vivi <rodrigo.vivi@intel.com>
Signed-off-by: José Roberto de Souza <jose.souza@intel.com>
Reviewed-by: Lucas De Marchi <lucas.demarchi@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20190730224753.14907-1-jose.souza@intel.com
Stop assuming we only get called with irqs-on for disarming the
breadcrumbs, and do a full save/restore spin_lock_irq.
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Mika Kuoppala <mika.kuoppala@linux.intel.com>
Reviewed-by: Mika Kuoppala <mika.kuoppala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20190813132916.20382-2-chris@chris-wilson.co.uk
In this case we want to apply the mask and then shift so the
parentheses is needed.
SPANK! SPANK! SPANK! Naughty programmer!
Fixes: 9749a5b6c0 ("drm/i915/tgl: Fix the read of the DDI that transcoder is attached to")
Cc: Lucas De Marchi <lucas.demarchi@intel.com>
Cc: Chris Wilson <chris@chris-wilson.co.uk>
Reviewed-by: Lucas De Marchi <lucas.demarchi@intel.com>
Reviewed-by: Chris Wilson <chris@chris-wilson.co.uk>
Signed-off-by: José Roberto de Souza <jose.souza@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20190812175405.14479-1-jose.souza@intel.com
Double check the end of the privilege buffer to make sure the size
of the privilege buffer remains unchanged after copy.
v4:
- Refine the commit message. (Zhenyu)
v3:
- To get the right offset of the batch buffer end cmd. (Yan)
v2:
- Use lightweight way to audit batch buffer end. (Yan)
Reviewed-by: Yan Zhao <yan.y.zhao@intel.com>
Signed-off-by: Tina Zhang <tina.zhang@intel.com>
Signed-off-by: Zhenyu Wang <zhenyuw@linux.intel.com>
Add valid length check for the commands with variable length.
v2: remove the macro definition. (Zhenyu)
v3: refine the LRI command. (Zhenyu)
Reviewed-by: Zhenyu Wang <zhenyuw@linux.intel.com>
Signed-off-by: Gao, Fred <fred.gao@intel.com>
Signed-off-by: Zhenyu Wang <zhenyuw@linux.intel.com>
Add the constant valid length of MI command.
v2: Add F_VAL_CONST flag. (Zhenyu Wang)
Reviewed-by: Zhenyu Wang <zhenyuw@linux.intel.com>
Signed-off-by: Gao, Fred <fred.gao@intel.com>
Signed-off-by: Zhenyu Wang <zhenyuw@linux.intel.com>
Add utility for valid command length check.
v2: Add F_VAL_CONST flag to identify the value is const
although LEN maybe variable. (Zhenyu)
v3: unused code removal, flag rename/conflict. (Zhenyu)
v4: redefine F_IP_ADVANCE_CUSTOM and move the check function to
next patch. (Zhenyu)
Reviewed-by: Zhenyu Wang <zhenyuw@linux.intel.com>
Signed-off-by: Gao, Fred <fred.gao@intel.com>
Signed-off-by: Zhenyu Wang <zhenyuw@linux.intel.com>
Factor out tlb and mocs register offset table to fix the issues reported
by klocwork, #512 and #550. Mostly, the reason why the klocwork reports
these problems is because there can be possbilities for platforms, which
have more rings than the ring offset table, to take the dirty data from
the stack as the register offset. It results to a random HW register
offset writting in this scenairo when doing context switch between vGPUs.
After the factoring, the ring offset table of TLB and MOCS should be per
platform.
v2:
- Enable TLB register switch for GEN8. (Zhenyu)
Reviewed-by: Zhenyu Wang <zhenyuw@linux.intel.com>
Signed-off-by: Zhi Wang <zhi.a.wang@intel.com>
Signed-off-by: Zhenyu Wang <zhenyuw@linux.intel.com>
When calling debugfs functions, there is no need to ever check the
return value. The function can work or not, but the code logic should
never do something different based on this.
Because there is no need to check these functions, a number of local
functions can be made to return void to simplify things as nothing can
fail.
Cc: Zhenyu Wang <zhenyuw@linux.intel.com>
Cc: Zhi Wang <zhi.a.wang@intel.com>
Cc: Jani Nikula <jani.nikula@linux.intel.com>
Cc: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>
Cc: Rodrigo Vivi <rodrigo.vivi@intel.com>
Cc: David Airlie <airlied@linux.ie>
Cc: Daniel Vetter <daniel@ffwll.ch>
Cc: intel-gvt-dev@lists.freedesktop.org
Cc: intel-gfx@lists.freedesktop.org
Cc: dri-devel@lists.freedesktop.org
Reviewed-by: Zhenyu Wang <zhenyuw@linux.intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Zhenyu Wang <zhenyuw@linux.intel.com>
We don't care about internal firmware status changes unless
we are doing some real debugging. Note that our CI is not
using DRM_I915_DEBUG_GUC config by default so use it.
v2: protect against accidental overwrites (Chris)
Signed-off-by: Michal Wajdeczko <michal.wajdeczko@intel.com>
Cc: Daniele Ceraolo Spurio <daniele.ceraolospurio@intel.com>
Cc: Chris Wilson <chris@chris-wilson.co.uk>
Reviewed-by: Chris Wilson <chris@chris-wilson.co.uk>
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Link: https://patchwork.freedesktop.org/patch/msgid/20190813081559.23936-1-michal.wajdeczko@intel.com
Since execlists and the guc have diverged in their port tracking, we
cannot simply reuse the execlists cancellation code as it leads to
unbalanced reference counting. Use a local, simpler routine for the guc.
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Daniele Ceraolo Spurio <daniele.ceraolospurio@intel.com>
Reviewed-by: Daniele Ceraolo Spurio <daniele.ceraolospurio@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20190812203626.3948-1-chris@chris-wilson.co.uk
We rely on the tasklet to update the GT PM refcount, so we can't disable
it even if we've processed all the requests for the engine because we
might have detected the request completion before the interrupt arrived.
Since on all platforms on which we plan to support guc submission we
don't allow disabling the breadcrumb interrupts, we can further siplify
the park/unpark flow by removing the interrupt pin/unpin. A BUG_ON has
been added to catch changes to this flow that would require us to
restore some kind of pinning.
v2: split removal of engine_pin/unpin_breadcrumbs_irq to its own
patch (chris)
Signed-off-by: Daniele Ceraolo Spurio <daniele.ceraolospurio@intel.com>
Cc: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Michal Wajdeczko <michal.wajdeczko@intel.com>
Reviewed-by: Chris Wilson <chris@chris-wilson.co.uk>
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Link: https://patchwork.freedesktop.org/patch/msgid/20190812233152.2172-1-daniele.ceraolospurio@intel.com
Remove the raw i915_active_request tracking in favour of the higher
level i915_active tracking for the sole purpose of making the lockless
transition easier in later patches.
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Reviewed-by: Matthew Auld <matthew.auld@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20190812174804.26180-2-chris@chris-wilson.co.uk
We were using the last_fence to track the last request that used this
vma that might be interpreted by a fence register and forced ourselves
to wait for this request before modifying any fence register that
overlapped our vma. Due to requirement that we need to track any XY_BLT
command, linear or tiled, this in effect meant that we have to track the
vma for its active lifespan anyway, so we can forgo the explicit
last_fence tracking and just use the whole vma->active.
Another solution would be to pipeline the register updates, and would
help resolve some long running stalls for gen3 (but only gen 2 and 3!)
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Reviewed-by: Matthew Auld <matthew.auld@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20190812174804.26180-1-chris@chris-wilson.co.uk
i915_irq.c is large. It serves as the central dispatch and handler for
all of our device interrupts. Lets break it up by pulling out the GT
interrupt handlers.
Based on a patch by Chris Wilson.
Signed-off-by: Andi Shyti <andi.shyti@intel.com>
Reviewed-by: Chris Wilson <chris@chris-wilson.co.uk>
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Link: https://patchwork.freedesktop.org/patch/msgid/20190811210633.18417-1-chris@chris-wilson.co.uk
i915_irq.c is large. It serves as the central dispatch and handler for
all of our device interrupts. Pull out the GT pm interrupt handling
(leaving the central dispatch) so that we can encapsulate the logic a
little better.
Based on a patch by Chris Wilson.
Signed-off-by: Andi Shyti <andi.shyti@intel.com>
Reviewed-by: Chris Wilson <chris@chris-wilson.co.uk>
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Link: https://patchwork.freedesktop.org/patch/msgid/20190811142801.2460-1-chris@chris-wilson.co.uk
