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| author | Chris Wilson <chris@chris-wilson.co.uk> | 2019-11-08 13:35:11 +0300 |
|---|---|---|
| committer | Chris Wilson <chris@chris-wilson.co.uk> | 2019-11-08 14:37:03 +0300 |
| commit | d79e1bd676f090f359a30e9fff4b992dcc071347 (patch) | |
| tree | a89ccb93043e3f269f5ace84da74c18d6e913820 /drivers/gpu/drm/i915/i915_pmu.c | |
| parent | c1c82d267ae8b42de0802c31fabeb843189adb9d (diff) | |
| download | linux-d79e1bd676f090f359a30e9fff4b992dcc071347.tar.xz | |
drm/i915/pmu: Only use exclusive mmio access for gen7
On gen7, we have to avoid concurrent access to the same mmio cacheline,
and so coordinate all mmio access with the uncore->lock. However, for
pmu, we want to avoid perturbing the system and disabling interrupts
unnecessarily, so restrict the w/a to gen7 where it is requied to
prevent machine hangs.
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/20191108103511.20951-2-chris@chris-wilson.co.uk
Diffstat (limited to 'drivers/gpu/drm/i915/i915_pmu.c')
| -rw-r--r-- | drivers/gpu/drm/i915/i915_pmu.c | 21 |
1 files changed, 19 insertions, 2 deletions
diff --git a/drivers/gpu/drm/i915/i915_pmu.c b/drivers/gpu/drm/i915/i915_pmu.c index 8e74f40413b8..4804775644bf 100644 --- a/drivers/gpu/drm/i915/i915_pmu.c +++ b/drivers/gpu/drm/i915/i915_pmu.c @@ -292,6 +292,16 @@ add_sample(struct i915_pmu_sample *sample, u32 val) sample->cur += val; } +static bool exclusive_mmio_access(const struct drm_i915_private *i915) +{ + /* + * We have to avoid concurrent mmio cache line access on gen7 or + * risk a machine hang. For a fun history lesson dig out the old + * userspace intel_gpu_top and run it on Ivybridge or Haswell! + */ + return IS_GEN(i915, 7); +} + static void engines_sample(struct intel_gt *gt, unsigned int period_ns) { @@ -304,6 +314,7 @@ engines_sample(struct intel_gt *gt, unsigned int period_ns) for_each_engine(engine, gt, id) { struct intel_engine_pmu *pmu = &engine->pmu; + spinlock_t *mmio_lock; unsigned long flags; bool busy; u32 val; @@ -311,7 +322,12 @@ engines_sample(struct intel_gt *gt, unsigned int period_ns) if (!intel_engine_pm_get_if_awake(engine)) continue; - spin_lock_irqsave(&engine->uncore->lock, flags); + mmio_lock = NULL; + if (exclusive_mmio_access(i915)) + mmio_lock = &engine->uncore->lock; + + if (unlikely(mmio_lock)) + spin_lock_irqsave(mmio_lock, flags); val = ENGINE_READ_FW(engine, RING_CTL); if (val == 0) /* powerwell off => engine idle */ @@ -342,7 +358,8 @@ engines_sample(struct intel_gt *gt, unsigned int period_ns) add_sample(&pmu->sample[I915_SAMPLE_BUSY], period_ns); skip: - spin_unlock_irqrestore(&engine->uncore->lock, flags); + if (unlikely(mmio_lock)) + spin_unlock_irqrestore(mmio_lock, flags); intel_engine_pm_put(engine); } } |