From 6ec81b82732e2b4a5ac0853fd33919ff1ca94238 Mon Sep 17 00:00:00 2001 From: Arnd Bergmann Date: Wed, 27 May 2020 16:05:08 +0200 Subject: drm/i915/pmu: avoid an maybe-uninitialized warning Conditional spinlocks make it hard for gcc and for lockdep to follow the code flow. This one causes a warning with at least gcc-9 and higher: In file included from include/linux/irq.h:14, from drivers/gpu/drm/i915/i915_pmu.c:7: drivers/gpu/drm/i915/i915_pmu.c: In function 'i915_sample': include/linux/spinlock.h:289:3: error: 'flags' may be used uninitialized in this function [-Werror=maybe-uninitialized] 289 | _raw_spin_unlock_irqrestore(lock, flags); \ | ^~~~~~~~~~~~~~~~~~~~~~~~~~~ drivers/gpu/drm/i915/i915_pmu.c:288:17: note: 'flags' was declared here 288 | unsigned long flags; | ^~~~~ Split out the part between the locks into a separate function for readability and to let the compiler figure out what the logic actually is. Fixes: d79e1bd676f0 ("drm/i915/pmu: Only use exclusive mmio access for gen7") Signed-off-by: Arnd Bergmann Reviewed-by: Chris Wilson Signed-off-by: Chris Wilson Link: https://patchwork.freedesktop.org/patch/msgid/20200527140526.1458215-1-arnd@arndb.de --- drivers/gpu/drm/i915/i915_pmu.c | 84 ++++++++++++++++++++--------------------- 1 file changed, 42 insertions(+), 42 deletions(-) (limited to 'drivers/gpu/drm') diff --git a/drivers/gpu/drm/i915/i915_pmu.c b/drivers/gpu/drm/i915/i915_pmu.c index f6f44ad5e335..802837de1767 100644 --- a/drivers/gpu/drm/i915/i915_pmu.c +++ b/drivers/gpu/drm/i915/i915_pmu.c @@ -269,12 +269,48 @@ static bool exclusive_mmio_access(const struct drm_i915_private *i915) return IS_GEN(i915, 7); } +static void engine_sample(struct intel_engine_cs *engine, unsigned int period_ns) +{ + struct intel_engine_pmu *pmu = &engine->pmu; + bool busy; + u32 val; + + val = ENGINE_READ_FW(engine, RING_CTL); + if (val == 0) /* powerwell off => engine idle */ + return; + + if (val & RING_WAIT) + add_sample(&pmu->sample[I915_SAMPLE_WAIT], period_ns); + if (val & RING_WAIT_SEMAPHORE) + add_sample(&pmu->sample[I915_SAMPLE_SEMA], period_ns); + + /* No need to sample when busy stats are supported. */ + if (intel_engine_supports_stats(engine)) + return; + + /* + * While waiting on a semaphore or event, MI_MODE reports the + * ring as idle. However, previously using the seqno, and with + * execlists sampling, we account for the ring waiting as the + * engine being busy. Therefore, we record the sample as being + * busy if either waiting or !idle. + */ + busy = val & (RING_WAIT_SEMAPHORE | RING_WAIT); + if (!busy) { + val = ENGINE_READ_FW(engine, RING_MI_MODE); + busy = !(val & MODE_IDLE); + } + if (busy) + add_sample(&pmu->sample[I915_SAMPLE_BUSY], period_ns); +} + static void engines_sample(struct intel_gt *gt, unsigned int period_ns) { struct drm_i915_private *i915 = gt->i915; struct intel_engine_cs *engine; enum intel_engine_id id; + unsigned long flags; if ((i915->pmu.enable & ENGINE_SAMPLE_MASK) == 0) return; @@ -283,53 +319,17 @@ engines_sample(struct intel_gt *gt, unsigned int period_ns) return; for_each_engine(engine, gt, id) { - struct intel_engine_pmu *pmu = &engine->pmu; - spinlock_t *mmio_lock; - unsigned long flags; - bool busy; - u32 val; - if (!intel_engine_pm_get_if_awake(engine)) continue; - 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 */ - goto skip; - - if (val & RING_WAIT) - add_sample(&pmu->sample[I915_SAMPLE_WAIT], period_ns); - if (val & RING_WAIT_SEMAPHORE) - add_sample(&pmu->sample[I915_SAMPLE_SEMA], period_ns); - - /* No need to sample when busy stats are supported. */ - if (intel_engine_supports_stats(engine)) - goto skip; - - /* - * While waiting on a semaphore or event, MI_MODE reports the - * ring as idle. However, previously using the seqno, and with - * execlists sampling, we account for the ring waiting as the - * engine being busy. Therefore, we record the sample as being - * busy if either waiting or !idle. - */ - busy = val & (RING_WAIT_SEMAPHORE | RING_WAIT); - if (!busy) { - val = ENGINE_READ_FW(engine, RING_MI_MODE); - busy = !(val & MODE_IDLE); + if (exclusive_mmio_access(i915)) { + spin_lock_irqsave(&engine->uncore->lock, flags); + engine_sample(engine, period_ns); + spin_unlock_irqrestore(&engine->uncore->lock, flags); + } else { + engine_sample(engine, period_ns); } - if (busy) - add_sample(&pmu->sample[I915_SAMPLE_BUSY], period_ns); -skip: - if (unlikely(mmio_lock)) - spin_unlock_irqrestore(mmio_lock, flags); intel_engine_pm_put_async(engine); } } -- cgit v1.2.3