drm/i915: Enable inject_load_failure only in DEBUG config

We're using i915_inject_load_failure() to inject dummy
faults during driver load, but since this is debug utility
we shouldn't expose it in default config as it consumes
both code and data.

add/remove: 0/1 grow/shrink: 0/2 up/down: 0/-302 (-302)
Function                                     old     new   delta
__i915_inject_load_failure                    61       -     -61
i915_gem_init                               1331    1268     -63
i915_driver_load                            5923    5745    -178
Total: Before=1177454, After=1177152, chg -0.03%

add/remove: 0/1 grow/shrink: 0/0 up/down: 0/-4 (-4)
Data                                         old     new   delta
i915_load_fail_count                           4       -      -4
Total: Before=56762, After=56758, chg -0.01%

add/remove: 4/8 grow/shrink: 0/1 up/down: 245/-591 (-346)
RO Data                                      old     new   delta
__param_str_inject_load_failure               20       -     -20
__UNIQUE_ID_inject_load_failuretype200        34       -     -34
__param_inject_load_failure                   40       -     -40
__func__                                    4998    4896    -102
__UNIQUE_ID_inject_load_failure201           150       -    -150
Total: Before=119095, After=118749, chg -0.29%

Signed-off-by: Michal Wajdeczko <michal.wajdeczko@intel.com>
Cc: Chris Wilson <chris@chris-wilson.co.uk>
Link: https://patchwork.freedesktop.org/patch/msgid/20180201173248.3912-1-michal.wajdeczko@intel.com
Reviewed-by: Chris Wilson <chris@chris-wilson.co.uk>
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>

drivers/gpu/drm/i915/i915_drv.c

@@ -55,6 +55,7 @@
 
 static struct drm_driver driver;
 
+#if IS_ENABLED(CONFIG_DRM_I915_DEBUG)
 static unsigned int i915_load_fail_count;
 
 bool __i915_inject_load_failure(const char *func, int line)
@@ -70,6 +71,7 @@ bool __i915_inject_load_failure(const char *func, int line)
 
 	return false;
 }
+#endif
 
 #define FDO_BUG_URL "https://bugs.freedesktop.org/enter_bug.cgi?product=DRI"
 #define FDO_BUG_MSG "Please file a bug at " FDO_BUG_URL " against DRM/Intel " \
@@ -107,8 +109,12 @@ __i915_printk(struct drm_i915_private *dev_priv, const char *level,
 
 static bool i915_error_injected(struct drm_i915_private *dev_priv)
 {
+#if IS_ENABLED(CONFIG_DRM_I915_DEBUG)
 	return i915_modparams.inject_load_failure &&
 	       i915_load_fail_count == i915_modparams.inject_load_failure;
+#else
+	return false;
+#endif
 }
 
 #define i915_load_error(dev_priv, fmt, ...)				     \

drivers/gpu/drm/i915/i915_drv.h

@@ -104,9 +104,13 @@
 #define I915_STATE_WARN_ON(x)						\
 	I915_STATE_WARN((x), "%s", "WARN_ON(" __stringify(x) ")")
 
+#if IS_ENABLED(CONFIG_DRM_I915_DEBUG)
 bool __i915_inject_load_failure(const char *func, int line);
 #define i915_inject_load_failure() \
 	__i915_inject_load_failure(__func__, __LINE__)
+#else
+#define i915_inject_load_failure() false
+#endif
 
 typedef struct {
 	uint32_t val;

drivers/gpu/drm/i915/i915_params.c

@@ -167,8 +167,10 @@ i915_param_named_unsafe(huc_firmware_path, charp, 0400,
 i915_param_named_unsafe(enable_dp_mst, bool, 0600,
 	"Enable multi-stream transport (MST) for new DisplayPort sinks. (default: true)");
 
+#if IS_ENABLED(CONFIG_DRM_I915_DEBUG)
 i915_param_named_unsafe(inject_load_failure, uint, 0400,
 	"Force an error after a number of failure check points (0:disabled (default), N:force failure at the Nth failure check point)");
+#endif
 
 i915_param_named(enable_dpcd_backlight, bool, 0600,
 	"Enable support for DPCD backlight control (default:false)");