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* [RFC] drm/i915: Introduce GEM_MAYBE_BUILD_BUG_ON
@ 2017-04-11 13:57 Michal Wajdeczko
  2017-04-11 15:28 ` ✓ Fi.CI.BAT: success for " Patchwork
  2017-04-12 11:13 ` [RFC] " Tvrtko Ursulin
  0 siblings, 2 replies; 5+ messages in thread
From: Michal Wajdeczko @ 2017-04-11 13:57 UTC (permalink / raw)
  To: intel-gfx

This is slightly weaker version of MAYBE_BUILD_BUG_ON that allows
us to avoid adding implicit BUG but still detect as much as possible
during the build. With this new macro we can fix the problem with
GCC 4.4.7 that wrongly triggers build break in wait_for_atomic()
when invoked with non-const parameter.

Fixes: 1d1a9774 ("drm/i915: Extend intel_wait_for_register_fw() with fast timeout")
Signed-off-by: Michal Wajdeczko <michal.wajdeczko@intel.com>
Suggested-by: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
Cc: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
Cc: Chris Wilson <chris@chris-wilson.co.uk>
---
 drivers/gpu/drm/i915/i915_gem.h  | 9 +++++++++
 drivers/gpu/drm/i915/intel_drv.h | 2 +-
 2 files changed, 10 insertions(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/i915/i915_gem.h b/drivers/gpu/drm/i915/i915_gem.h
index 5a49487..ce23cf1 100644
--- a/drivers/gpu/drm/i915/i915_gem.h
+++ b/drivers/gpu/drm/i915/i915_gem.h
@@ -42,6 +42,15 @@
 #define GEM_DEBUG_BUG_ON(expr)
 #endif
 
+#define GEM_MAYBE_BUILD_BUG_ON(expr) \
+	do { \
+		if (__builtin_constant_p((expr))) \
+			BUILD_BUG_ON(expr); \
+		else \
+			GEM_BUG_ON(expr); \
+	} while (0)
+
+
 #define I915_NUM_ENGINES 5
 
 #endif /* __I915_GEM_H__ */
diff --git a/drivers/gpu/drm/i915/intel_drv.h b/drivers/gpu/drm/i915/intel_drv.h
index 7bc0c25..ce50ec4 100644
--- a/drivers/gpu/drm/i915/intel_drv.h
+++ b/drivers/gpu/drm/i915/intel_drv.h
@@ -88,7 +88,7 @@
 	int cpu, ret, timeout = (US) * 1000; \
 	u64 base; \
 	_WAIT_FOR_ATOMIC_CHECK(ATOMIC); \
-	BUILD_BUG_ON((US) > 50000); \
+	GEM_MAYBE_BUILD_BUG_ON((US) > 50000); \
 	if (!(ATOMIC)) { \
 		preempt_disable(); \
 		cpu = smp_processor_id(); \
-- 
2.7.4

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^ permalink raw reply related	[flat|nested] 5+ messages in thread

end of thread, other threads:[~2017-04-12 12:58 UTC | newest]

Thread overview: 5+ messages (download: mbox.gz follow: Atom feed
-- links below jump to the message on this page --
2017-04-11 13:57 [RFC] drm/i915: Introduce GEM_MAYBE_BUILD_BUG_ON Michal Wajdeczko
2017-04-11 15:28 ` ✓ Fi.CI.BAT: success for " Patchwork
2017-04-12 11:13 ` [RFC] " Tvrtko Ursulin
2017-04-12 11:29   ` Chris Wilson
2017-04-12 12:58   ` Michal Wajdeczko

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