Commit 6ec81b82 authored by Arnd Bergmann's avatar Arnd Bergmann Committed by Chris Wilson

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: d79e1bd6 ("drm/i915/pmu: Only use exclusive mmio access for gen7")
Signed-off-by: default avatarArnd Bergmann <arnd@arndb.de>
Reviewed-by: default avatarChris Wilson <chris@chris-wilson.co.uk>
Signed-off-by: default avatarChris Wilson <chris@chris-wilson.co.uk>
Link: https://patchwork.freedesktop.org/patch/msgid/20200527140526.1458215-1-arnd@arndb.de
parent 0109a16e
...@@ -269,39 +269,15 @@ static bool exclusive_mmio_access(const struct drm_i915_private *i915) ...@@ -269,39 +269,15 @@ static bool exclusive_mmio_access(const struct drm_i915_private *i915)
return IS_GEN(i915, 7); return IS_GEN(i915, 7);
} }
static void static void engine_sample(struct intel_engine_cs *engine, unsigned int period_ns)
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;
if ((i915->pmu.enable & ENGINE_SAMPLE_MASK) == 0)
return;
if (!intel_gt_pm_is_awake(gt))
return;
for_each_engine(engine, gt, id) {
struct intel_engine_pmu *pmu = &engine->pmu; struct intel_engine_pmu *pmu = &engine->pmu;
spinlock_t *mmio_lock;
unsigned long flags;
bool busy; bool busy;
u32 val; 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); val = ENGINE_READ_FW(engine, RING_CTL);
if (val == 0) /* powerwell off => engine idle */ if (val == 0) /* powerwell off => engine idle */
goto skip; return;
if (val & RING_WAIT) if (val & RING_WAIT)
add_sample(&pmu->sample[I915_SAMPLE_WAIT], period_ns); add_sample(&pmu->sample[I915_SAMPLE_WAIT], period_ns);
...@@ -310,7 +286,7 @@ engines_sample(struct intel_gt *gt, unsigned int period_ns) ...@@ -310,7 +286,7 @@ engines_sample(struct intel_gt *gt, unsigned int period_ns)
/* No need to sample when busy stats are supported. */ /* No need to sample when busy stats are supported. */
if (intel_engine_supports_stats(engine)) if (intel_engine_supports_stats(engine))
goto skip; return;
/* /*
* While waiting on a semaphore or event, MI_MODE reports the * While waiting on a semaphore or event, MI_MODE reports the
...@@ -326,10 +302,34 @@ engines_sample(struct intel_gt *gt, unsigned int period_ns) ...@@ -326,10 +302,34 @@ engines_sample(struct intel_gt *gt, unsigned int period_ns)
} }
if (busy) if (busy)
add_sample(&pmu->sample[I915_SAMPLE_BUSY], period_ns); 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;
if (!intel_gt_pm_is_awake(gt))
return;
for_each_engine(engine, gt, id) {
if (!intel_engine_pm_get_if_awake(engine))
continue;
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);
}
skip:
if (unlikely(mmio_lock))
spin_unlock_irqrestore(mmio_lock, flags);
intel_engine_pm_put_async(engine); intel_engine_pm_put_async(engine);
} }
} }
......
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