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Commit 5f77eeb0 authored by Daniel Vetter's avatar Daniel Vetter
Browse files

drm/i915: Use BUILD_BUG if possible in the i915 WARN_ON 



Faster feedback to errors is always better. This is inspired by the
addition to WARN_ONs to mask/enable helpers for registers to make sure
callers have the arguments ordered correctly: Pretty much always the
arguments are static.

We use WARN_ON(1) a lot in default switch statements though where we
should always handle all cases. So add a new macro specifically for
that.

The idea to use __builtin_constant_p is from Chris Wilson.

v2: Use the ({}) gcc-ism to avoid the static inline, suggested by
Dave. My first attempt used __cond as the temp var, which is the same
used by BUILD_BUG_ON, but with inverted sense. Hilarity ensued, so
sprinkle i915 into the name.

Also use a temporary variable to only evaluate the condition once,
suggested by Damien.

v3: It's crazy but apparently 32bit gcc can't compile out the
BUILD_BUG_ON in a lot of cases and just falls over. I have no idea
why, but until clue grows just disable this nifty idea on 32bit
builds. Reported by 0-day builder.

v4: Got it all wrong, apparently its the gcc version. We need 4.9+.
Now reported by Imre.

v5: Chris suggested to add the case to MISSING_CASE for speedier
debug.

v6: Even some gcc 4.9 versions don't see through the maze, so give up
for now. Keep the skeleton and MISSING_CASE stuff though.

Cc: Imre Deak <imre.deak@intel.com>
Cc: Damien Lespiau <damien.lespiau@intel.com>
Cc: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Jani Nikula <jani.nikula@linux.intel.com>
Cc: Dave Gordon <david.s.gordon@intel.com>
Signed-off-by: default avatarDaniel Vetter <daniel.vetter@intel.com>
parent 3f7531c3

drivers/gpu/drm/i915/i915_debugfs.c

+1 −1
Original line number Diff line number Diff line
@@ -2347,7 +2347,7 @@ static const char *power_domain_str(enum intel_display_power_domain domain) 
	case POWER_DOMAIN_INIT:

		return "INIT";

	default:

		WARN_ON(1);

		MISSING_CASE(domain);

		return "?";

	}

}

drivers/gpu/drm/i915/i915_drv.h

+13 −1
Original line number Diff line number Diff line
@@ -58,7 +58,19 @@ 
#define DRIVER_DATE		"20141205"



#undef WARN_ON

#define WARN_ON(x)		WARN(x, "WARN_ON(" #x ")")

/* Many gcc seem to no see through this and fall over :( */

#if 0

#define WARN_ON(x) ({ \

	bool __i915_warn_cond = (x); \

	if (__builtin_constant_p(__i915_warn_cond)) \

		BUILD_BUG_ON(__i915_warn_cond); \

	WARN(__i915_warn_cond, "WARN_ON(" #x ")"); })

#else

#define WARN_ON(x) WARN((x), "WARN_ON(" #x ")")

#endif



#define MISSING_CASE(x) WARN(1, "Missing switch case (%lu) in %s\n", \

			     (long) (x), __func__);



enum pipe {

	INVALID_PIPE = -1,

drivers/gpu/drm/i915/i915_gem_gtt.c

+3 −3
Original line number Diff line number Diff line
@@ -132,7 +132,7 @@ static gen6_gtt_pte_t snb_pte_encode(dma_addr_t addr, 
		pte |= GEN6_PTE_UNCACHED;

		break;

	default:

		WARN_ON(1);

		MISSING_CASE(level);

	}



	return pte;
@@ -156,7 +156,7 @@ static gen6_gtt_pte_t ivb_pte_encode(dma_addr_t addr, 
		pte |= GEN6_PTE_UNCACHED;

		break;

	default:

		WARN_ON(1);

		MISSING_CASE(level);

	}



	return pte;
@@ -1146,7 +1146,7 @@ int i915_ppgtt_init_hw(struct drm_device *dev) 
	else if (INTEL_INFO(dev)->gen >= 8)

		gen8_ppgtt_enable(dev);

	else

		WARN_ON(1);

		MISSING_CASE(INTEL_INFO(dev)->gen);



	if (ppgtt) {

		for_each_ring(ring, dev_priv, i) {

drivers/gpu/drm/i915/intel_display.c

+2 −2
Original line number Diff line number Diff line
@@ -4847,7 +4847,7 @@ static void cherryview_set_cdclk(struct drm_device *dev, int cdclk) 
		cmd = 0;

		break;

	default:

		WARN_ON(1);

		MISSING_CASE(cdclk);

		return;

	}
@@ -8224,7 +8224,7 @@ static void i9xx_update_cursor(struct drm_crtc *crtc, u32 base) 
				cntl |= CURSOR_MODE_256_ARGB_AX;

				break;

			default:

				WARN_ON(1);

				MISSING_CASE(intel_crtc->cursor_width);

				return;

		}

		cntl |= pipe << 28; /* Connect to correct pipe */

drivers/gpu/drm/i915/intel_uncore.c

+2 −2
Original line number Diff line number Diff line
@@ -1202,7 +1202,7 @@ void intel_uncore_init(struct drm_device *dev) 


	switch (INTEL_INFO(dev)->gen) {

	default:

		WARN_ON(1);

		MISSING_CASE(INTEL_INFO(dev)->gen);

		return;

	case 9:

		ASSIGN_WRITE_MMIO_VFUNCS(gen9);
@@ -1300,7 +1300,7 @@ int i915_reg_read_ioctl(struct drm_device *dev, 
		reg->val = I915_READ8(reg->offset);

		break;

	default:

		WARN_ON(1);

		MISSING_CASE(entry->size);

		ret = -EINVAL;

		goto out;

	}