From 5f77eeb05c9ee1de03fbe695b41362aae401726a Mon Sep 17 00:00:00 2001 From: Daniel Vetter Date: Mon, 8 Dec 2014 16:40:10 +0100 Subject: [PATCH] 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 Cc: Damien Lespiau Cc: Chris Wilson Cc: Jani Nikula Cc: Dave Gordon Signed-off-by: Daniel Vetter --- drivers/gpu/drm/i915/i915_debugfs.c | 2 +- drivers/gpu/drm/i915/i915_drv.h | 14 +++++++++++++- drivers/gpu/drm/i915/i915_gem_gtt.c | 6 +++--- drivers/gpu/drm/i915/intel_display.c | 4 ++-- drivers/gpu/drm/i915/intel_uncore.c | 4 ++-- 5 files changed, 21 insertions(+), 9 deletions(-) diff --git a/drivers/gpu/drm/i915/i915_debugfs.c b/drivers/gpu/drm/i915/i915_debugfs.c index 165a38f36009..479e0c119111 100644 --- a/drivers/gpu/drm/i915/i915_debugfs.c +++ b/drivers/gpu/drm/i915/i915_debugfs.c @@ -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 "?"; } } diff --git a/drivers/gpu/drm/i915/i915_drv.h b/drivers/gpu/drm/i915/i915_drv.h index c74dc946cbf6..5f4cca3ef01c 100644 --- a/drivers/gpu/drm/i915/i915_drv.h +++ b/drivers/gpu/drm/i915/i915_drv.h @@ -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, diff --git a/drivers/gpu/drm/i915/i915_gem_gtt.c b/drivers/gpu/drm/i915/i915_gem_gtt.c index ac03a382000b..ce4e46c443a1 100644 --- a/drivers/gpu/drm/i915/i915_gem_gtt.c +++ b/drivers/gpu/drm/i915/i915_gem_gtt.c @@ -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) { diff --git a/drivers/gpu/drm/i915/intel_display.c b/drivers/gpu/drm/i915/intel_display.c index 841af6c1f50b..878c4857ff49 100644 --- a/drivers/gpu/drm/i915/intel_display.c +++ b/drivers/gpu/drm/i915/intel_display.c @@ -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 */ diff --git a/drivers/gpu/drm/i915/intel_uncore.c b/drivers/gpu/drm/i915/intel_uncore.c index 46de8d75b4bf..883d2febb705 100644 --- a/drivers/gpu/drm/i915/intel_uncore.c +++ b/drivers/gpu/drm/i915/intel_uncore.c @@ -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; } -- 2.20.1