If we find ourselves waiting on a MI_SEMAPHORE_WAIT, either within the
user batch or in our own preamble, the engine raises a
GT_WAIT_ON_SEMAPHORE interrupt. We can unmask that interrupt and so
respond to a semaphore wait by yielding the timeslice, if we have
another context to yield to!
The only real complication is that the interrupt is only generated for
the start of the semaphore wait, and is asynchronous to our
process_csb() -- that is, we may not have registered the timeslice before
we see the interrupt. To ensure we don't miss a potential semaphore
blocking forward progress (e.g. selftests/live_timeslice_preempt) we mark
the interrupt and apply it to the next timeslice regardless of whether it
was active at the time.
v2: We use semaphores in preempt-to-busy, within the timeslicing
implementation itself! Ergo, when we do insert a preemption due to an
expired timeslice, the new context may start with the missed semaphore
flagged by the retired context and be yielded, ad infinitum. To avoid
this, read the context id at the time of the semaphore interrupt and
only yield if that context is still active.
Fixes: 8ee36e048c ("drm/i915/execlists: Minimalistic timeslicing")
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
Cc: Kenneth Graunke <kenneth@whitecape.org>
Reviewed-by: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20200407130811.17321-1-chris@chris-wilson.co.uk
If we want to percolate information back from the HW, up through the GEM
context, we need to wait until the intel_context is scheduled out for
the last time. This is handled by the retirement of the intel_context's
barrier, i.e. by listening to the pulse after the notional unpin. So
wait until the intel_context is finally retired before releasing the
engine, so that we can inspect the final context state and pass it on.
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/20200406155840.1728-3-chris@chris-wilson.co.uk
Allow the caller to also wait upon the barriers stored in i915_active.
v2: Hook up i915_request_await_active(I915_ACTIVE_AWAIT_BARRIER) as well
for completeness, and avoid the lazy GEM_BUG_ON()!
v3: Pull flush_lazy_signals() under the active-ref protection as it too
walks the rbtree and so we must be careful that we do not free it as we
iterate.
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/20200406155840.1728-2-chris@chris-wilson.co.uk
Later use will require asynchronous waits on the active timelines, but
will not utilize an async wait on the exclusive channel. Make the await
on the exclusive fence explicit in the selection flags.
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/20200406155840.1728-1-chris@chris-wilson.co.uk
__i915_gem_object_flush_map() takes a byte range, so feed it the written
bytes and do not mistake the u32 index as bytes!
Fixes: a679f58d05 ("drm/i915: Flush pages on acquisition")
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Matthew Auld <matthew.william.auld@gmail.com>
Cc: <stable@vger.kernel.org> # v5.2+
Reviewed-by: Matthew Auld <matthew.william.auld@gmail.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20200406114821.10949-1-chris@chris-wilson.co.uk
On TypeC ports if a sink deasserts/reasserts its HPD signal, generating
a hotplug interrupt without the sink getting unplugged/replugged from
the connector, there can be an up to 3 seconds delay until the AUX
channel gets functional. To avoid detection failures this delay causes
retry the detection for 5 seconds.
I noticed this on ICL/TGL RVPs and a DELL XPS 13 7390 ICL laptop.
References: https://gitlab.freedesktop.org/drm/intel/issues/1067
Signed-off-by: Imre Deak <imre.deak@intel.com>
Reviewed-by: José Roberto de Souza <jose.souza@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20200330095425.29113-2-imre.deak@intel.com
On TypeC connectors we need to retry the detection after hotplug events
for a longer time, so add a retry counter to support this. The next
patch will add detection retries on TypeC ports needing this.
Signed-off-by: Imre Deak <imre.deak@intel.com>
Reviewed-by: José Roberto de Souza <jose.souza@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20200330095425.29113-1-imre.deak@intel.com
While extremely unlikely to be populated, we could capture a request on
the virtual engine which we should free along with the virtual engine.
Fixes: 43acd6516c ("drm/i915: Keep a per-engine request pool")
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Reviewed-by: Janusz Krzysztofik <janusz.krzysztofik@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20200403203303.10903-1-chris@chris-wilson.co.uk
If we submit, we do not start timeslicing until we process the CS event
that marks the start of the context running on HW. So in the selftest,
be sure to wait until we have processed the pending events before
asserting that timeslicing has begun.
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Acked-by: Michael J. Ruhl <michael.j.ruhl@intel.com>
Reviewed-by: Mika Kuoppala <mika.kuoppala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20200403190209.21818-1-chris@chris-wilson.co.uk
It is wrong to block the user thread in the next poll when OA data is
already available which could not fit in the user buffer provided in
the previous read. In several cases the exact user buffer size is not
known. Blocking user space in poll can lead to data loss when the
buffer size used is smaller than the available data.
This change fixes this issue and allows user space to read all OA data
even when using a buffer size smaller than the available data using
multiple non-blocking reads rather than staying blocked in poll till
the next timer interrupt.
v2: Fix ret value for blocking reads (Umesh)
v3: Mistake during patch send (Ashutosh)
v4: Remove -EAGAIN from comment (Umesh)
v5: Improve condition for clearing pollin and return (Lionel)
v6: Improve blocking read loop and other cleanups (Lionel)
v7: Added Cc stable
Testcase: igt/perf/polling-small-buf
Reviewed-by: Lionel Landwerlin <lionel.g.landwerlin@intel.com>
Signed-off-by: Ashutosh Dixit <ashutosh.dixit@intel.com>
Cc: Umesh Nerlige Ramappa <umesh.nerlige.ramappa@intel.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Link: https://patchwork.freedesktop.org/patch/msgid/20200403010120.3067-1-ashutosh.dixit@intel.com
Make sure we revoke the user's mmaps of this vma to force them to take a
pagefault *before* we remove the associated aperture detiling register.
Fixes: 0d86ee3509 ("drm/i915/gt: Make fence revocation unequivocal")
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Matthew Auld <matthew.auld@intel.com>
Reviewed-by: Matthew Auld <matthew.auld@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20200403160951.8271-1-chris@chris-wilson.co.uk
Move the final DP_TP_CTL frobbing of port sync to the master
encoder's enable hook. Now neatly out of sight from the high level
modeset code.
And thus we've eliminated all the special casing of port sync
in the high level modeset code.
Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20200313164831.5980-14-ville.syrjala@linux.intel.com
Reviewed-by: José Roberto de Souza <jose.souza@intel.com>
We're going to want access to the atomic state for iterating
the slave crtcs when enabling the port sync master crtc. Pass
the atomic state all the way down.
The alternative would be yet another encoder hook which we'll
have to call after all the normal modeset stuff is done. Not
really a fan of yet another hook just for this.
Note that during readout state sanitation we are now going
to pass NULL as the atomic state since we don't have one.
We need to change that and then we can also s/crtc_state/crtc/
and s/conn_state/conn/ for the encoder hooks as well.
Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20200313164831.5980-13-ville.syrjala@linux.intel.com
Reviewed-by: José Roberto de Souza <jose.souza@intel.com>
Currently only port sync pipes do the sequence such that
we first do the modeset part for every pipe and then do
the plane/etc. updates. Let's follow that apporach for
all pipes in skl+ so that we can properly integrate the
port sync into the normal modeset flow.
v2: Remove now stale TODO of port sync slave entries[]
s/oldnew/new/
Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20200313164831.5980-12-ville.syrjala@linux.intel.com
Reviewed-by: José Roberto de Souza <jose.souza@intel.com>
Don't assume there is just one port sync slave. We might have several.
v2: Fix unitialized new_crtc_state usage (José)
Fix clearing of modeset_pipes for slaves
s/oldnew/new/
Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20200313164831.5980-11-ville.syrjala@linux.intel.com
Reviewed-by: José Roberto de Souza <jose.souza@intel.com>
Transcoder port sync was introduced to the hardware in BDW. We
can trivially enable it for SKL+ since the same codepaths are
already used for ICL+ port sync. The only difference is the actual
location of the bits we need to poke.
We leave BDW out (at least for now) since it uses different modeset
paths that haven't been adapted for port sync, and IIRC using the
feature would involve some extra workarounds we've not implemented.
Pre-BDW hardware does not support port sync so we'd have to tweak
the modeset sequence to start the pipes as close together as possible
and hope for the best. So far no one has seriously tried to implement
that.
Closes: https://gitlab.freedesktop.org/drm/intel/issues/27
Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20200313164831.5980-9-ville.syrjala@linux.intel.com
Reviewed-by: Manasi Navare <manasi.d.navare@intel.com>
We have a bunch of code that would like to know which
CPU transcoders are actually present in the hardware. Rather than
use various ad-hoc methods let's just include a full bitmask in
the device info, alongside pipe_mask.
v2: Rebase
Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20200318170235.15176-1-ville.syrjala@linux.intel.com
Reviewed-by: José Roberto de Souza <jose.souza@intel.com>
We use timer->expires == 0 to detect if a timer had been cancelled, but
it's a valid expiration we could set. Just skip using 0 and set the
expiry for the next jiffie.
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/20200403073657.13427-1-chris@chris-wilson.co.uk
Add a tiny per-engine request mempool so that we should always have a
request available for powermanagement allocations from tricky
contexts. This reserve is expected to be only used for kernel
contexts when barriers must be emitted [almost] without fail.
The main consumer for this reserved request is expected to be engine-pm,
for which we know that there will always be at least the previous pm
request that we can reuse under mempressure (so there should always be
a spare request for engine_park()).
This is an alternative to using a comparatively bulky mempool, which
requires custom handling for both our reserved allocation requirement
and to protect our TYPESAFE_BY_RCU slab cache. The advantage of mempool
would be that it would allow us to keep a larger per-engine request
pool. However, converting over to mempool is straightforward should the
need arise.
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Janusz Krzysztofik <janusz.krzysztofik@linux.intel.com>
Cc: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
Reviewed-and-tested-by: Janusz Krzysztofik <janusz.krzysztofik@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20200402184037.21630-1-chris@chris-wilson.co.uk
This workaround now applies to all steppings, not just A0.
Wa_1409085225 is a temporary A0-only W/A however it is
identical to Wa_14010229206 and hence the combined workaround
is made permanent.
Bspec: 52890
Signed-off-by: Swathi Dhanavanthri <swathi.dhanavanthri@intel.com>
Tested-by: Rafael Antognolli <rafael.antognolli@intel.com>
Reviewed-by: Matt Roper <matthew.d.roper@intel.com>
[mattrope: added missing blank line]
Signed-off-by: Matt Roper <matthew.d.roper@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20200326234955.16155-1-swathi.dhanavanthri@intel.com
In order to kill off a hostile context, we need to be able to reset the
GPU. So check that is supported prior to beginning the test.
Reported-by: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
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/20200402205839.25065-1-chris@chris-wilson.co.uk
Now that we can peek at GEM->engines[] and obtain a reference to them
using RCU, do so for instances where we can safely iterate the
potentially old copy of the engines. For setting, we can do this when we
know the engine properties are copied over before swapping, so we know
the new engines already have the global property and we update the old
before they are discarded. For reading, we only need to be safe; as we
do so on behalf of the user, their races are their own problem.
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/20200402124218.6375-1-chris@chris-wilson.co.uk
If we receive the error interrupt before the CS interrupt, we may find
ourselves without an active request to reset, skipping the GPU reset.
All because the attempt to reset was too early.
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/20200401110435.30389-1-chris@chris-wilson.co.uk
drivers/gpu/drm/i915/gt/uc/intel_uc_fw.c:205: warning: Excess function parameter 'supported' description in 'intel_uc_fw_init_early'
drivers/gpu/drm/i915/gt/uc/intel_uc_fw.c:205: warning: Excess function parameter 'platform' description in 'intel_uc_fw_init_early'
drivers/gpu/drm/i915/gt/uc/intel_uc_fw.c:205: warning: Excess function parameter 'rev' description in 'intel_uc_fw_init_early'
drivers/gpu/drm/i915/gt/uc/intel_guc_log.c:696: warning: Function parameter or member 'log' not described in 'intel_guc_log_info'
drivers/gpu/drm/i915/gt/uc/intel_guc_log.c:696: warning: Excess function parameter 'guc' description in 'intel_guc_log_info'
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/20200330212254.18236-1-chris@chris-wilson.co.uk
We cached the number of vma bound to the object in order to speed up
shrinker decisions. This has been superseded by being more proactive in
removing objects we cannot shrink from the shrinker lists, and so we can
drop the clumsy attempt at atomically counting the bind count and
comparing it to the number of pinned mappings of the object. This will
only get more clumsier with asynchronous binding and unbinding.
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/20200401223924.16667-1-chris@chris-wilson.co.uk
If we must revoke the fence because the VMA is no longer present, or
because the fence no longer applies, ensure that we do and convert it
into an error if we try but cannot.
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/20200401210104.15907-3-chris@chris-wilson.co.uk
Only GPU activity via the GGTT fence is asynchronous, we know that we
control the CPU access directly, so we only need to wait for the GPU to
stop using the fence before we relinquish it.
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/20200401210104.15907-1-chris@chris-wilson.co.uk
If the current node/entry location is occupied, and the object is not
pinned, try assigning it some free space. We cannot wait here, so if in
doubt, we unreserve and try to grab all at once.
v2: Use the final pin_flags so that we won't have to move the object if
we find the wrong free space.
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/20200401194135.5442-1-chris@chris-wilson.co.uk
If the user passes in a readonly reloc[], by the time we notice we have
already committed to modifying the execobjects, or have indeed done so
already. Reporting the failure just compounds the issue as we have no
second pass to fall back to anymore.
"Be damned if you do, and damned if you don't."
Testcase: igt/gem_exec_reloc/readonly
Fixes: 7dc8f11437 ("drm/i915/gem: Drop relocation slowpath")
References: fddcd00a49 ("drm/i915: Force the slow path after a user-write error")
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Matthew Auld <matthew.auld@intel.com>
Cc: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>
Reviewed-by: Andi Shyti <andi.shyti@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20200331162150.3635-1-chris@chris-wilson.co.uk
When we allocate space in the GGTT we may have to allocate a larger
region than will be populated by the object to accommodate fencing. Make
sure that this space beyond the end of the buffer points safely into
scratch space, in case the HW tries to access it anyway (e.g. fenced
access to the last tile row).
v2: Preemptively / conservatively guard gen6 ggtt as well.
Reported-by: Imre Deak <imre.deak@intel.com>
References: https://gitlab.freedesktop.org/drm/intel/-/issues/1554
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Matthew Auld <matthew.auld@intel.com>
Cc: Imre Deak <imre.deak@intel.com>
Cc: stable@vger.kernel.org
Reviewed-by: Matthew Auld <matthew.auld@intel.com>
Reviewed-by: Imre Deak <imre.deak@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20200331152348.26946-1-chris@chris-wilson.co.uk
For CI it is enough to point out a single failure
in isolation. However it is beneficial to gather
info in logs for transients further down
the line.
Do not stop into first comparison failure but
continue probing forward.
v2: for all engines and poisons (Chris)
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/20200331135403.16906-1-mika.kuoppala@linux.intel.com
Since we may be attempting to reset an active engine, we try to freeze
it in place before resetting -- to be on the safe side. We can go one
step further if we are using the CS flow semaphore to prevent the
context switching into the next.
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/20200331091459.29179-2-chris@chris-wilson.co.uk
Since we may kick more than engine, and may kick each one a couple of
times, coalesce the tasklet execution to the end. This also ensures that
we have the chance to run the tasklet immediately after priority
bumping.
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/20200331114852.11583-1-chris@chris-wilson.co.uk
Specification was updated with vswing tables for different
configurations.
Also reordering icl_mg_phy_ddi_buf_trans struct to match table order.
BSpec: 21735
Signed-off-by: José Roberto de Souza <jose.souza@intel.com>
Reviewed-by: Clinton Taylor <clinton.a.taylor@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20200330210044.130510-3-jose.souza@intel.com
DDI ports have its encoders initialized with INTEL_OUTPUT_DDI type and
later eDP ports that have the type changed to INTEL_OUTPUT_EDP.
But for all other DDI ports it can drive HDMI or DP depending on what
user connects to the ports.
ehl_get_combo_buf_trans() and tgl_get_combo_buf_trans() was checking
for INTEL_OUTPUT_DP that was never true, causing wrong vswing tables
being used.
So here replacing the INTEL_OUTPUT_DP checks by the valid output types
that this functions receives as parameters. HDMI cases will be
correctly handled as it do not use encoder->type, instead it calls the
functions with INTEL_OUTPUT_HDMI as type parameter and HDMI don't have
retraining.
v2:
changed INTEL_OUTPUT_DDI to INTEL_OUTPUT_EDP and INTEL_OUTPUT_HDMI
Fixes: bd3cf6f7ce ("drm/i915/dp/tgl+: Update combo phy vswing tables")
Cc: Clinton A Taylor <clinton.a.taylor@intel.com>
Cc: Matt Roper <matthew.d.roper@intel.com>
Cc: Ville Syrjälä <ville.syrjala@linux.intel.com>
Reviewed-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Signed-off-by: José Roberto de Souza <jose.souza@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20200330210044.130510-1-jose.souza@intel.com
The DDI IO power well must not be enabled for a TypeC port in TBT mode,
ensure this during driver loading/system resume.
This gets rid of error messages like
[drm] *ERROR* power well DDI E TC2 IO state mismatch (refcount 1/enabled 0)
and avoids leaking the power ref when disabling the output.
Cc: <stable@vger.kernel.org> # v5.4+
Signed-off-by: Imre Deak <imre.deak@intel.com>
Reviewed-by: José Roberto de Souza <jose.souza@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20200330152244.11316-1-imre.deak@intel.com
process_csb: 0000:00:02.0 bcs0: cs-irq head=4, tail=5
process_csb: 0000:00:02.0 bcs0: csb[5]: status=0x00008002:0x60000020
trace_ports: 0000:00:02.0 bcs0: preempted { ff84:45154! prio 2 }
trace_ports: 0000:00:02.0 bcs0: promote { ff84:45155* prio 2 }
trace_ports: 0000:00:02.0 bcs0: submit { ff84:45156 prio 2 }
process_csb: 0000:00:02.0 bcs0: cs-irq head=5, tail=6
process_csb: 0000:00:02.0 bcs0: csb[6]: status=0x00000018:0x60000020
trace_ports: 0000:00:02.0 bcs0: completed { ff84:45155* prio 2 }
process_csb: 0000:00:02.0 bcs0: ring:{start:0x00178000, head:0928, tail:0928, ctl:00000000, mode:00000200}
process_csb: 0000:00:02.0 bcs0: rq:{start:00178000, head:08b0, tail:08f0, seqno:ff84:45155, hwsp:45156},
process_csb: 0000:00:02.0 bcs0: ctx:{start:00178000, head:e000928, tail:0928},
process_csb: GEM_BUG_ON("context completed before request")
In this sequence, we can see that although we have submitted the next
request [ff84:45156] to HW (via ELSP[]) it has not yet reported the
lite-restore. Instead, we see the completion event of the currently
active request [ff84:45155] but at the time of processing that event,
the breadcrumb has not yet been written. Though by the time we do print
out the debug info, the seqno write of ff84:45156 has landed!
Therefore there is a serialisation problem between the seqno writes and
CS events, not just between the CS buffer and its head/tail pointers as
previously observed on Icelake.
This is not a huge problem, as we don't strictly rely on the breadcrumb
to determine HW activity, but it may indicate that interrupt delivery is
before the seqno write, aka bringing back the plague of missed
interrupts from yesteryear. However, there is no indication of this
wider problem, so let's just flush the seqno read before reporting an
error. If it persists after the fresh read we can worry again.
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/20200330234318.30638-1-chris@chris-wilson.co.uk
Upon a GPU reset, we copy the default context image over top of the
guilty image. This will rollback the CTX_TIMESTAMP register to before
our value of ce->runtime.last. Reset both back to 0 so that we do not
encounter an underflow on the next schedule out after resume.
This should not be a huge issue in practice, as hangs should be rare in
correct code.
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/20200330125827.5804-1-chris@chris-wilson.co.uk
