drm/i915: Add fault injection support

Add support for forcing an error at selected places in the driver. As an
example add 4 options to fail during driver loading.

Requested by Chris.

v2:
- Add fault point for modeset initialization
- Print debug message when injecting an error
v3:
- Rename inject_fault to inject_load_failure, rename the related macros
  and helper accordingly (Chris)
- Use a counter instead of a mask to identify the failure point (Daniel)
- Mark the module option as _unsafe and keep i915_params ordered (Joonas)
v4:
- Rebase on latest -nightly
v5:
- Use DRM_INFO instead of DRM_DEBUG_DRIVER, making it clearer in CI reports
  that a following error message is expected (IRC r-b from Chris on v5)

CC: Chris Wilson <chris@chris-wilson.co.uk>
CC: Daniel Vetter <daniel.vetter@ffwll.ch>
CC: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>
Signed-off-by: Imre Deak <imre.deak@intel.com>
Reviewed-by: Chris Wilson <chris@chris-wilson.co.uk>

1 files changed, 4 insertions, 0 deletions

diff --git a/drivers/gpu/drm/i915/i915_drv.h b/drivers/gpu/drm/i915/i915_drv.h
index e6d4b1ce130e..00c41a4bde2a 100644
--- a/drivers/gpu/drm/i915/i915_drv.h
+++ b/drivers/gpu/drm/i915/i915_drv.h
@@ -98,6 +98,10 @@
 #define I915_STATE_WARN_ON(x)						\
 	I915_STATE_WARN((x), "%s", "WARN_ON(" __stringify(x) ")")
 
+bool __i915_inject_load_failure(const char *func, int line);
+#define i915_inject_load_failure() \
+	__i915_inject_load_failure(__func__, __LINE__)
+
 static inline const char *yesno(bool v)
 {
 	return v ? "yes" : "no";