Something that I completely missed when implementing the new MST VCPI
atomic helpers is that with those helpers, there's technically a chance
of us having to grab additional modeset locks in ->compute_config() and
furthermore, that means we have the potential to hit a normal modeset
deadlock. However, because ->compute_config() only returns a bool this
means we can't return -EDEADLK when we need to drop locks and try again
which means we end up just failing the atomic check permanently. Whoops.
So, fix this by modifying ->compute_config() to pass down an actual
error code instead of a bool so that the atomic check can be restarted
on modeset deadlocks.
Thanks to Ville Syrjälä for pointing this out!
Changes since v1:
* Add some newlines
* Return only -EINVAL from hsw_crt_compute_config()
* Propogate return code from intel_dp_compute_dsc_params()
* Change all of the intel_dp_compute_link_config*() variants
* Don't miss if (hdmi_port_clock_valid()) branch in
intel_hdmi_compute_config()
[Cherry-picked from drm-misc-next to drm-intel-next-queued to fix
linux-next & drm-tip conflict, while waiting for proper propagation of
the DP MST series that this commit fixes. In hindsight, a topic branch
might have been a better approach for it.]
Signed-off-by: Lyude Paul <lyude@redhat.com>
Cc: Ville Syrjälä <ville.syrjala@linux.intel.com>
Fixes: eceae14724 ("drm/dp_mst: Start tracking per-port VCPI allocations")
Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=109320
Reviewed-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20190115200800.3121-1-lyude@redhat.com
(cherry picked from commit 96550555a7)
Signed-off-by: Jani Nikula <jani.nikula@intel.com>
Acked-by: Daniel Vetter <daniel@ffwll.ch>
Since commit 93065ac753 ("mm, oom: distinguish blockable mode for mmu
notifiers") we have been able to report failure from
mmu_invalidate_range_start which allows us to use a trylock on the
struct_mutex to avoid potential recursion and report -EBUSY instead.
Furthermore, this allows us to pull the work into the main callback and
avoid the sleight-of-hand in using a workqueue to avoid lockdep.
However, not all paths to mmu_invalidate_range_start are prepared to
handle failure, so instead of reporting the recursion, deal with it by
propagating the failure upwards, who can decide themselves to handle it
or report it.
v2: Mark up the recursive lock behaviour and comment on the various weak
points.
v3: Follow commit 3824e41975 ("drm/i915: Use mutex_lock_killable() from
inside the shrinker") and also use mutex_lock_killable().
v3.1: No leak on EINTR.
Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=108375
References: 93065ac753 ("mm, oom: distinguish blockable mode for mmu notifiers")
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/20190115124442.3500-1-chris@chris-wilson.co.uk
On Braswell, under heavy stress, if we update the GGTT while
simultaneously accessing another region inside the GTT, we are returned
the wrong values. To prevent this we stop the machine to update the GGTT
entries so that no memory traffic can occur at the same time.
This was first spotted in
commit 5bab6f60cb
Author: Chris Wilson <chris@chris-wilson.co.uk>
Date: Fri Oct 23 18:43:32 2015 +0100
drm/i915: Serialise updates to GGTT with access through GGTT on Braswell
but removed again in forlorn hope with
commit 4509276ee8
Author: Chris Wilson <chris@chris-wilson.co.uk>
Date: Mon Feb 20 12:47:18 2017 +0000
drm/i915: Remove Braswell GGTT update w/a
However, gem_concurrent_blit is once again only stable with the patch
applied and CI is detecting the odd failure in forked gem_mmap_gtt tests
(which smell like the same issue). Fwiw, a wide variety of CPU memory
barriers (around GGTT flushing, fence updates, PTE updates) and GPU
flushes/invalidates (between requests, after PTE updates) were tried as
part of the investigation to find an alternate cause, nothing comes
close to serialised GGTT updates.
Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=105591
Testcase: igt/gem_concurrent_blit
Testcase: igt/gem_mmap_gtt/*forked*
References: 5bab6f60cb ("drm/i915: Serialise updates to GGTT with access through GGTT on Braswell")
References: 4509276ee8 ("drm/i915: Remove Braswell GGTT update w/a")
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/20190114211729.30352-1-chris@chris-wilson.co.uk
Currently Ironlake operates under the assumption that rpm awake (and its
error checking is disabled). As such, we have missed a few places where we
access registers without taking the rpm wakeref and thus trigger
warnings. intel_ips being one culprit.
As this involved adding a potentially sleeping rpm_get, we have to
rearrange the spinlocks slightly and so switch to acquiring a device-ref
under the spinlock rather than hold the spinlock for the whole
operation. To be consistent, we make the change in pattern common to the
intel_ips interface even though this adds a few more atomic operations
than necessary in a few cases.
v2: Sagar noted the mb around setting mch_dev were overkill as we only
need ordering there, and that i915_emon_status was still using
struct_mutex for no reason, but lacked rpm.
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Jani Nikula <jani.nikula@intel.com>
Reviewed-by: John Harrison <John.C.Harrison@Intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20190114142129.24398-21-chris@chris-wilson.co.uk
The majority of runtime-pm operations are bounded and scoped within a
function; these are easy to verify that the wakeref are handled
correctly. We can employ the compiler to help us, and reduce the number
of wakerefs tracked when debugging, by passing around cookies provided
by the various rpm_get functions to their rpm_put counterpart. This
makes the pairing explicit, and given the required wakeref cookie the
compiler can verify that we pass an initialised value to the rpm_put
(quite handy for double checking error paths).
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Jani Nikula <jani.nikula@intel.com>
Reviewed-by: Mika Kuoppala <mika.kuoppala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20190114142129.24398-16-chris@chris-wilson.co.uk
The majority of runtime-pm operations are bounded and scoped within a
function; these are easy to verify that the wakeref are handled
correctly. We can employ the compiler to help us, and reduce the number
of wakerefs tracked when debugging, by passing around cookies provided
by the various rpm_get functions to their rpm_put counterpart. This
makes the pairing explicit, and given the required wakeref cookie the
compiler can verify that we pass an initialised value to the rpm_put
(quite handy for double checking error paths).
For regular builds, the compiler should be able to eliminate the unused
local variables and the program growth should be minimal. Fwiw, it came
out as a net improvement as gcc was able to refactor rpm_get and
rpm_get_if_in_use together,
v2: Just s/rpm_put/rpm_put_unchecked/ everywhere, leaving the manual
mark up for smaller more targeted patches.
v3: Mention the cookie in Returns
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Jani Nikula <jani.nikula@intel.com>
Cc: Mika Kuoppala <mika.kuoppala@linux.intel.com>
Reviewed-by: Mika Kuoppala <mika.kuoppala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20190114142129.24398-2-chris@chris-wilson.co.uk
Everytime we take a wakeref, record the stack trace of where it was
taken; clearing the set if we ever drop back to no owners. For debugging
a rpm leak, we can look at all the current wakerefs and check if they
have a matching rpm_put.
v2: Use skip=0 for unwinding the stack as it appears our noinline
function doesn't appear on the stack (nor does save_stack_trace itself!)
v3: Allow rpm->debug_count to disappear between inspections and so
avoid calling krealloc(0) as that may return a ZERO_PTR not NULL! (Mika)
v4: Show who last acquire/released the runtime pm
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Jani Nikula <jani.nikula@intel.com>
Cc: Mika Kuoppala <mika.kuoppala@linux.intel.com>
Reviewed-by: Mika Kuoppala <mika.kuoppala@linux.intel.com>
Tested-by: Mika Kuoppala <mika.kuoppala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20190114142129.24398-1-chris@chris-wilson.co.uk
The wait-for-idle used from within the shrinker_lock_uninterruptible
depends on the struct_mutex locking state being known and declared to
i915_request_wait(). As it is conceivable that we reach the vmap
notifier from underneath struct_mutex (and so keep on relying on the
mutex_trylock_recursive), we should not blindly call i915_request_wait.
In the process we can remove the dubious polling to acquire
struct_mutex, and simply act, or not, on a successful trylock.
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/20190109164204.23935-2-chris@chris-wilson.co.uk
If the current process is being killed (it was interrupted with SIGKILL
or equivalent), it will not make any progress in page allocation and we
can abort performing the shrinking on its behalf. So we can use
mutex_lock_killable() instead (although this path should only be
reachable from kswapd currently).
Tvrtko pointed out that it should also be reachable from debugfs, which
he would prefer retain its interruptiblity. As a compromise, killable is a
step in the right direction!
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/20190109164204.23935-1-chris@chris-wilson.co.uk
