Start using device specific parameters instead of module parameters for
most things. The module parameters become the immutable initial values
for i915 parameters. The device specific parameters in i915->params
start life as a copy of i915_modparams. Any later changes are only
reflected in the debugfs.
The stragglers are:
* i915.force_probe and i915.modeset. Needed before dev_priv is
available. This is fine because the parameters are read-only and never
modified.
* i915.verbose_state_checks. Passing dev_priv to I915_STATE_WARN and
I915_STATE_WARN_ON would result in massive and ugly churn. This is
handled by not exposing the parameter via debugfs, and leaving the
parameter writable in sysfs. This may be fixed up in follow-up work.
* i915.inject_probe_failure. Only makes sense in terms of the module,
not the device. This is handled by not exposing the parameter via
debugfs.
v2: Fix uc i915 lookup code (Michał Winiarski)
Cc: Juha-Pekka Heikkilä <juha-pekka.heikkila@intel.com>
Cc: Venkata Sandeep Dhanalakota <venkata.s.dhanalakota@intel.com>
Cc: Michał Winiarski <michal.winiarski@intel.com>
Reviewed-by: Rodrigo Vivi <rodrigo.vivi@intel.com>
Acked-by: Michał Winiarski <michal.winiarski@intel.com>
Signed-off-by: Jani Nikula <jani.nikula@intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/20200618150402.14022-1-jani.nikula@intel.com
We only emit the renderstate once now during module load, it is no
longer a concern that we are delaying context creation and so do not
need to so eagerly optimise. Since the last time we have looked at the
renderstate, we have a pin_map / flush_map facility that supports simple
single mappings, replacing the open-coded kmap_atomic() and
prepare_write. As it should be a single page, of which we only write a
small portion, we stick to a simple WB [kmap] and use clflush on !llc
platforms, rather than creating a temporary WC vmapping for the single
page.
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/20200619234543.17499-2-chris@chris-wilson.co.uk
Smatch warns that we may iterate over an empty array of gt->engines[].
One hopes that this is impossible, but nevertheless we can simply
appease smatch by initialising the timestamp to zero before we starting
probing the busy-time from the engines.
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/20200619151938.21740-1-chris@chris-wilson.co.uk
Return the monotonic timestamp (ktime_get()) at the time of sampling the
busy-time. This is used in preference to taking ktime_get() separately
before or after the read seqlock as there can be some large variance in
reported timestamps. For selftests trying to ascertain that we are
reporting accurate to within a few microseconds, even a small delay
leads to the test failing.
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
Reviewed-by: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20200617130916.15261-2-chris@chris-wilson.co.uk
A couple of very simple tests to ensure that the basic properties of
per-engine busyness accounting [0% and 100% busy] are faithful.
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Reviewed-by: Mika Kuoppala <mika.kuoppala@linux.intel.com>
Cc: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20200617130916.15261-1-chris@chris-wilson.co.uk
Like live_unlite_ring, but instead of simply looking at the impact of
intel_ring_direction(), check that preemption more generally works with
different depths of queued requests in the ring.
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/20200616233733.18050-1-chris@chris-wilson.co.uk
Not too long ago, we realised we had issues with a rolling back a
context so far for a preemption request we considered the resubmit not
to be a rollback but a forward roll. This means we would issue a lite
restore instead of forcing a full restore, continuing execution of the
old requests rather than causing a preemption. Add a selftest to
exercise such a far rollback, such that if we were to skip the full
restore, we would execute invalid instructions in the ring and hang.
Note that while I was able to confirm that this causes us to do a
lite-restore preemption rollback (with commit e36ba817fa ("drm/i915/gt:
Incrementally check for rewinding") disabled), it did not trick the HW
into rolling past the old RING_TAIL. Myybe on other HW.
References: e36ba817fa ("drm/i915/gt: Incrementally check for rewinding")
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/20200616185518.11948-1-chris@chris-wilson.co.uk
Fix inconsistent IS_ERR and PTR_ERR in live_timeslice_nopreempt().
The proper pointer to be passed as argument to PTR_ERR() is ce.
This bug was detected with the help of Coccinelle.
Fixes: b72f02d78e ("drm/i915/gt: Prevent timeslicing into unpreemptable requests")
Signed-off-by: Gustavo A. R. Silva <gustavoars@kernel.org>
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/20200616145452.GA25291@embeddedor
Alexandre Oliva has recently removed these files from Linux Libre
with concerns that the sources weren't available.
The sources are available on IGT repository, and only open source
tools are used to generate the {ivb,hsw}_clear_kernel.c files.
However, the remaining concern from Alexandre Oliva was around
GPL license and the source not been present when distributing
the code.
So, it looks like 2 alternatives are possible, the use of
linux-firmware.git repository to store the blob or making sure
that the source is also present in our tree. Since the goal
is to limit the i915 firmware to only the micro-controller blobs
let's make sure that we do include the asm sources here in our tree.
Btw, I tried to have some diligence here and make sure that the
asms that these commits are adding are truly the source for
the mentioned files:
igt$ ./scripts/generate_clear_kernel.sh -g ivb \
-m ~/mesa/build/src/intel/tools/i965_asm
Output file not specified - using default file "ivb-cb_assembled"
Generating gen7 CB Kernel assembled file "ivb_clear_kernel.c"
for i915 driver...
igt$ diff ~/i915/drm-tip/drivers/gpu/drm/i915/gt/ivb_clear_kernel.c \
ivb_clear_kernel.c
< * Generated by: IGT Gpu Tools on Fri 21 Feb 2020 05:29:32 AM UTC
> * Generated by: IGT Gpu Tools on Mon 08 Jun 2020 10:00:54 AM PDT
61c61
< };
> };
\ No newline at end of file
igt$ ./scripts/generate_clear_kernel.sh -g hsw \
-m ~/mesa/build/src/intel/tools/i965_asm
Output file not specified - using default file "hsw-cb_assembled"
Generating gen7.5 CB Kernel assembled file "hsw_clear_kernel.c"
for i915 driver...
igt$ diff ~/i915/drm-tip/drivers/gpu/drm/i915/gt/hsw_clear_kernel.c \
hsw_clear_kernel.c
5c5
< * Generated by: IGT Gpu Tools on Fri 21 Feb 2020 05:30:13 AM UTC
> * Generated by: IGT Gpu Tools on Mon 08 Jun 2020 10:01:42 AM PDT
61c61
< };
> };
\ No newline at end of file
Used IGT and Mesa master repositories from Fri Jun 5 2020)
IGT: 53e8c878a6fb ("tests/kms_chamelium: Force reprobe after replugging
the connector")
Mesa: 5d13c7477eb1 ("radv: set keep_statistic_info with
RADV_DEBUG=shaderstats")
Mesa built with: meson build -D platforms=drm,x11 -D dri-drivers=i965 \
-D gallium-drivers=iris -D prefix=/usr \
-D libdir=/usr/lib64/ -Dtools=intel \
-Dkulkan-drivers=intel && ninja -C build
v2: Header clean-up and include build instructions in a readme (Chris)
Modified commit message to respect check-patch
Reference: http://www.fsfla.org/pipermail/linux-libre/2020-June/003374.html
Reference: http://www.fsfla.org/pipermail/linux-libre/2020-June/003375.html
Fixes: 47f8253d2b ("drm/i915/gen7: Clear all EU/L3 residual contexts")
Cc: <stable@vger.kernel.org> # v5.7+
Cc: Alexandre Oliva <lxoliva@fsfla.org>
Cc: Prathap Kumar Valsan <prathap.kumar.valsan@intel.com>
Cc: Akeem G Abodunrin <akeem.g.abodunrin@intel.com>
Cc: Mika Kuoppala <mika.kuoppala@linux.intel.com>
Cc: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Jani Nikula <jani.nikula@intel.com>
Cc: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>
Signed-off-by: Rodrigo Vivi <rodrigo.vivi@intel.com>
Reviewed-by: Jon Bloomfield <jon.bloomfield@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20200610201807.191440-1-rodrigo.vivi@intel.com
Just in case everything fails (like for example "missed interrupt
syndrome" on Sandybridge), always flush the submission tasklet from the
heartbeat. This papers over such issues, but will still appear as a
second long glitch, and prevents us from detecting it unless we happen
to be performing a timed test.
v2: We rely on flush_submission() synchronizing with the tasklet on
another CPU.
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/20200615165013.22973-3-chris@chris-wilson.co.uk
gen3 does not fully flush MI stores to memory on MI_FLUSH, such that a
subsequent read from e.g. the sampler can bypass the store and read the
stale value from memory. This is a serious issue when we are using MI
stores to rewrite the batches for relocation, as it means that the batch
is reading from random user/kernel memory. While it is particularly
sensitive [and detectable] for relocations, reading stale data at any
time is a worry.
Having started with a small number of delaying stores and doubling until
no more incoherency was seen over a few hours (with and without
background memory pressure), 32 was the magic number.
Note that it definitely doesn't fix the issue, merely adds a long delay
between requests, sufficient to mostly hide the problem, enough to raise
the mtbf to several hours. This is merely a stop gap.
v2: Follow more closer with the gen5 w/a and include some
post-invalidate flushes as well.
Closes: https://gitlab.freedesktop.org/drm/intel/-/issues/2018
References: a889580c08 ("drm/i915: Flush GPU relocs harder for gen3")
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Mika Kuoppala <mika.kuoppala@linux.intel.com>
Cc: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>
Reviewed-by: Mika Kuoppala <mika.kuoppala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20200612123949.7093-1-chris@chris-wilson.co.uk
Reduce the smoke depth by trimming the number of contexts, repetitions
and wait times. This is in preparation for a less greedy scheduler that
tries to be fair across contexts, resulting in a great many more context
switches. A thousand context switches may be 50-100ms, causing us to
timeout as the HW is not fast enough to complete the deep smoketests.
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Reviewed-by: Andi Shyti <andi.shyti@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20200607222108.14401-5-chris@chris-wilson.co.uk
Since the process_csb() does not require us to hold the
engine->active.lock, we can move the opportunistic flush before
direction submission to outside of the lock.
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/20200612221113.9129-1-chris@chris-wilson.co.uk
With the removal of the internal wait-priority boosting, we can also
remove the selftest to ensure that those waits were being suppressed
from causing preemptions.
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Reviewed-by: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20200607222108.14401-4-chris@chris-wilson.co.uk
We have a test case to exercise resetting an engine while the other
engines are busy, all the TEST_SELF adds on top is that the target
engine also has background activity. In this case it is useful to first
test resetting the engine while there is background activity, as a
separate flag from exercising all others.
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/20200607222108.14401-3-chris@chris-wilson.co.uk
In commit 5ba32c7be8 ("drm/i915/execlists: Always force a context
reload when rewinding RING_TAIL"), we placed the check for rewinding a
context on actually submitting the next request in that context. This
was so that we only had to check once, and could do so with precision
avoiding as many forced restores as possible. For example, to ensure
that we can resubmit the same request a couple of times, we include a
small wa_tail such that on the next submission, the ring->tail will
appear to move forwards when resubmitting the same request. This is very
common as it will happen for every lite-restore to fill the second port
after a context switch.
However, intel_ring_direction() is limited in precision to movements of
upto half the ring size. The consequence being that if we tried to
unwind many requests, we could exceed half the ring and flip the sense
of the direction, so missing a force restore. As no request can be
greater than half the ring (i.e. 2048 bytes in the smallest case), we
can check for rollback incrementally. As we check against the tail that
would be submitted, we do not lose any sensitivity and allow lite
restores for the simple case. We still need to double check upon
submitting the context, to allow for multiple preemptions and
resubmissions.
Fixes: 5ba32c7be8 ("drm/i915/execlists: Always force a context reload when rewinding RING_TAIL")
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Mika Kuoppala <mika.kuoppala@linux.intel.com>
Cc: <stable@vger.kernel.org> # v5.4+
Reviewed-by: Bruce Chang <yu.bruce.chang@intel.com>
Reviewed-by: Mika Kuoppala <mika.kuoppala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20200609151723.12971-1-chris@chris-wilson.co.uk
In some of our hangtests, we try to reset an active engine while it is
spinning inside the recursive spinner. However, we also try to flood the
engine with requests that preempt the hang, and so should disable the
preemption to be sure that we reset the right request.
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/20200607222108.14401-2-chris@chris-wilson.co.uk
Sentinels are supposed to be last requests in the elsp queue, not the
only one, so adjust the assert accordingly.
Signed-off-by: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
Reviewed-by: Mika Kuoppala <mika.kuoppala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20200607222108.14401-1-chris@chris-wilson.co.uk
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
We may choose not to submit for a number of reasons, yet not fill both
ELSP. In which case we must start timeslicing (there will be no ACK
event on which to hook the start) if the queue would benefit from the
currently active context being evicted.
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/20200605122334.2798-2-chris@chris-wilson.co.uk
If we only submit the first port, leaving the second empty yet have
ready requests pending in the queue, use that to set the timeslicing
priority (i.e. the priority at which we will decided to enabling
timeslicing and evict the currently active context if the queue is of
equal priority after its quantum expired).
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/20200605122334.2798-1-chris@chris-wilson.co.uk
Add engine->fw_domain/active to the pretty printer for debug dumps and
debugfs.
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Mika Kuoppala <mika.kuoppala@linux.intel.com>
Cc: Venkata Sandeep Dhanalakota <venkata.s.dhanalakota@intel.com>
Reviewed-by: Mika Kuoppala <mika.kuoppala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20200605144705.31127-1-chris@chris-wilson.co.uk
Sometimes an engine might need to keep forcewake active while it is busy
submitting requests for a particular workaround. Track such nuisance
with engine->fw_domain.
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Reviewed-by: Mika Kuoppala <mika.kuoppala@linux.intel.com>
Cc: Venkata Sandeep Dhanalakota <venkata.s.dhanalakota@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20200604153145.21068-1-chris@chris-wilson.co.uk
Use the plain msec_to_jiffies() rather than the _timeout variant so we
round down and do not add an extra jiffy to our interval. For example,
with timeslicing we do not want to err on the longer side as any
fairness depends on catching hogging contexts on the GPU. Bring on
CFS.
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/20200604135938.3975-1-chris@chris-wilson.co.uk
Set GS Timer to 224. Combine with Wa_1604555607 due to register FF_MODE2
not being able to be read.
V2: Math issue fixed
Cc: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Caz Yokoyama <caz.yokoyama@intel.com>
Cc: Matt Atwood <matthew.s.atwood@intel.com>
Signed-off-by: Clint Taylor <clinton.a.taylor@intel.com>
Acked-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/20200603221150.14745-1-clinton.a.taylor@intel.com
We infrequently use the direct i915 backpointer from the i915_request,
so do we really need to waste the space in the struct for it? 8 bytes
from the most frequently allocated struct vs an 3 bytes and pointer
chasing in using rq->engine->i915?
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Reviewed-by: Akeem G Abodunrin <akeem.g.abodunrin@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20200602220953.21178-1-chris@chris-wilson.co.uk
If we injected an error (such as pretending the GuC firmware was
broken), then suppress the error message as it is expected and our CI
complains if it sees any *ERROR*.
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/20200603104657.25651-1-chris@chris-wilson.co.uk
For reasons that be, the HW only allows usersace to read its own
CTX_TIMESTAMP [context local HW runtime] on rcs. Make it available for
all by adding it to the whitelists.
v2: The change took effect from Cometlake.
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Reviewed-by: José Roberto de Souza <jose.souza@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20200602154839.6902-1-chris@chris-wilson.co.uk
Cometlake is a small refresh of Coffeelake, but since we have found out a
difference in the plaforms, we need to identify them as separate platforms.
Since we previously took Coffeelake/Cometlake as identical, update all
IS_COFFEELAKE() to also include IS_COMETLAKE().
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Reviewed-by: José Roberto de Souza <jose.souza@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20200602140541.5481-1-chris@chris-wilson.co.uk
As a timestamp will automatically update itself, it will not hold only
contexts we write into it, and will change from the baseline value
making us suspect that our writes are landing. As this confuses us and
we would need more careful treatment to detect invalid stores into the
timestamp, skip it when verifying the whitelists.
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Reviewed-by: José Roberto de Souza <jose.souza@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20200602154839.6902-1-chris@chris-wilson.co.uk
Pull the routines for writing CS packets out of intel_ring_submission
into their own files. These are low level operations for building CS
instructions, rather than the logic for filling the global ring buffer
with requests, and we will want to reuse them outside of this context.
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Acked-by: Mika Kuoppala <mika.kuoppala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20200601072446.19548-2-chris@chris-wilson.co.uk
We may choose to only submit ELSP[0], even though we have sufficient
requests to fill the whole ELSP. Normally, we only start timeslicing if
we fill more than one port, but in this case we need to start
timeslicing for the queue that we choose not to submit.
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/20200528205727.20309-1-chris@chris-wilson.co.uk
If the ring submission is stalled on an external request, nothing can be
submitted, not even the heartbeat in the kernel context. Since nothing
is running, resetting the engine/device does not unblock the system and
is pointless. We can see if the heartbeat is supposed to be running
before declaring foul.
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/20200528074109.28235-2-chris@chris-wilson.co.uk
Across suspend/resume, we clear the entire GGTT and rebuild from
scratch. In particular, we want to only preserve the global entries for
use by the HW, and delay reinstating the local binds until required by
the user. This means that we can evict any local binds in the global GTT,
saving any time in preserving their state, as they will be rebound on
demand.
References: https://gitlab.freedesktop.org/drm/intel/-/issues/1947
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/20200528082427.21402-2-chris@chris-wilson.co.uk
We should be able to skip restoring LOCAL (user) binds within the GGTT on
resume and let them be restored upon demand. However, our consistency
checks demand that the bind flags match the node state, and we cannot
simply clear the flags, we need to evict as well. For now, make sure we
restore the bind flags exactly upon resume.
Fixes: 0109a16ef3 ("drm/i915/gt: Clear LOCAL_BIND from shared GGTT on resume")
Fixes: bf0840cdb3 ("drm/i915/gt: Stop cross-polluting PIN_GLOBAL with PIN_USER with no-ppgtt")
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/20200528150452.7880-1-chris@chris-wilson.co.uk
We have a I915_REQUEST_NOPREEMPT flag that we set when we must prevent
the HW from preempting during the course of this request. We need to
honour this flag and protect the HW even if we have a heartbeat request,
or other maximum priority barrier, pending. As such, restrict the
timeslicing check to avoid preempting into the topmost priority band,
leaving the unpreemptable requests in blissful peace running
uninterrupted on the HW.
v2: Set the I915_PRIORITY_BARRIER to be less than
I915_PRIORITY_UNPREEMPTABLE so that we never submit a request
(heartbeat or barrier) that can legitimately preempt the current
non-premptable request.
Fixes: 2a98f4e65b ("drm/i915: add infrastructure to hold off preemption on a request")
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
Reviewed-by: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20200527162418.24755-1-chris@chris-wilson.co.uk
