diff options
| author | Tvrtko Ursulin <tvrtko.ursulin@intel.com> | 2016-06-29 12:27:22 +0100 |
|---|---|---|
| committer | Tvrtko Ursulin <tvrtko.ursulin@intel.com> | 2016-06-29 15:53:15 +0100 |
| commit | 18f4b8435c50888bb36cf8de3b7f0075f00dc12c (patch) | |
| tree | 22fc1a86c1c0461f418df08faccce9e92540d664 | |
| parent | c68b0ab2e08fd8913a794d11e74cbf5cd589b3df (diff) | |
drm/i915: Use atomic waits for short non-atomic ones
usleep_range is not recommended for waits shorten than 10us.
Make the wait_for_us use the atomic variant for such waits.
To do so we need to reimplement the _wait_for_atomic macro to
be safe with regards to preemption and interrupts.
v2: Reimplement _wait_for_atomic to be irq and preemption safe.
(Chris Wilson and Imre Deak)
v3: Fixed in_atomic check due rebase error.
v4: Build bug on non-constant timeouts.
v5: Compile away cpu migration code in atomic paths.
Signed-off-by: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
Cc: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Imre Deak <imre.deak@intel.com>
Cc: Mika Kuoppala <mika.kuoppala@intel.com>
Reviewed-by: Chris Wilson <chris@chris-wilson.co.uk>
Link: http://patchwork.freedesktop.org/patch/msgid/1467114710-29989-1-git-send-email-tvrtko.ursulin@linux.intel.com
| -rw-r--r-- | drivers/gpu/drm/i915/intel_drv.h | 62 |
1 files changed, 43 insertions, 19 deletions
diff --git a/drivers/gpu/drm/i915/intel_drv.h b/drivers/gpu/drm/i915/intel_drv.h index 3156d8df7921..98a5be4ec8c5 100644 --- a/drivers/gpu/drm/i915/intel_drv.h +++ b/drivers/gpu/drm/i915/intel_drv.h @@ -69,39 +69,63 @@ }) #define wait_for(COND, MS) _wait_for((COND), (MS) * 1000, 1000) -#define wait_for_us(COND, US) _wait_for((COND), (US), 1) /* If CONFIG_PREEMPT_COUNT is disabled, in_atomic() always reports false. */ #if defined(CONFIG_DRM_I915_DEBUG) && defined(CONFIG_PREEMPT_COUNT) -# define _WAIT_FOR_ATOMIC_CHECK WARN_ON_ONCE(!in_atomic()) +# define _WAIT_FOR_ATOMIC_CHECK(ATOMIC) WARN_ON_ONCE((ATOMIC) && !in_atomic()) #else -# define _WAIT_FOR_ATOMIC_CHECK do { } while (0) +# define _WAIT_FOR_ATOMIC_CHECK(ATOMIC) do { } while (0) #endif -#define _wait_for_atomic(COND, US) ({ \ - unsigned long end__; \ - int ret__ = 0; \ - _WAIT_FOR_ATOMIC_CHECK; \ +#define _wait_for_atomic(COND, US, ATOMIC) \ +({ \ + int cpu, ret, timeout = (US) * 1000; \ + u64 base; \ + _WAIT_FOR_ATOMIC_CHECK(ATOMIC); \ BUILD_BUG_ON((US) > 50000); \ - end__ = (local_clock() >> 10) + (US) + 1; \ - while (!(COND)) { \ - if (time_after((unsigned long)(local_clock() >> 10), end__)) { \ - /* Unlike the regular wait_for(), this atomic variant \ - * cannot be preempted (and we'll just ignore the issue\ - * of irq interruptions) and so we know that no time \ - * has passed since the last check of COND and can \ - * immediately report the timeout. \ - */ \ - ret__ = -ETIMEDOUT; \ + if (!(ATOMIC)) { \ + preempt_disable(); \ + cpu = smp_processor_id(); \ + } \ + base = local_clock(); \ + for (;;) { \ + u64 now = local_clock(); \ + if (!(ATOMIC)) \ + preempt_enable(); \ + if (COND) { \ + ret = 0; \ + break; \ + } \ + if (now - base >= timeout) { \ + ret = -ETIMEDOUT; \ break; \ } \ cpu_relax(); \ + if (!(ATOMIC)) { \ + preempt_disable(); \ + if (unlikely(cpu != smp_processor_id())) { \ + timeout -= now - base; \ + cpu = smp_processor_id(); \ + base = local_clock(); \ + } \ + } \ } \ + ret; \ +}) + +#define wait_for_us(COND, US) \ +({ \ + int ret__; \ + BUILD_BUG_ON(!__builtin_constant_p(US)); \ + if ((US) > 10) \ + ret__ = _wait_for((COND), (US), 10); \ + else \ + ret__ = _wait_for_atomic((COND), (US), 0); \ ret__; \ }) -#define wait_for_atomic(COND, MS) _wait_for_atomic((COND), (MS) * 1000) -#define wait_for_atomic_us(COND, US) _wait_for_atomic((COND), (US)) +#define wait_for_atomic(COND, MS) _wait_for_atomic((COND), (MS) * 1000, 1) +#define wait_for_atomic_us(COND, US) _wait_for_atomic((COND), (US), 1) #define KHz(x) (1000 * (x)) #define MHz(x) KHz(1000 * (x)) |