drm/i915: tame the chattermouth (v2)

Many distro's have mechanism in place to collect and automatically file
bugs for failed WARN()s.  And since i915 has a lot of hw state sanity
checks which result in WARN(), it generates quite a lot of noise which
is somewhat disconcerting to the end user.

Separate out the internal hw-is-in-the-state-I-expected checks into
I915_STATE_WARN()s and allow configuration via i915.verbose_checks module
param about whether this will generate a full blown stacktrace or just
DRM_ERROR().  The new moduleparam defaults to true, so by default there
is no change in behavior.  And even when disabled, you will still get
an error message logged.

v2: paint the macro names blue, clarify that the default behavior
    remains the same as before

Signed-off-by: Rob Clark <robdclark@gmail.com>
Acked-by: Jani Nikula <jani.nikula@intel.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>

1 files changed, 30 insertions, 0 deletions

diff --git a/drivers/gpu/drm/i915/i915_drv.h b/drivers/gpu/drm/i915/i915_drv.h
index eb4d64fecf8a..f3185293bed1 100644
--- a/drivers/gpu/drm/i915/i915_drv.h
+++ b/drivers/gpu/drm/i915/i915_drv.h
@@ -72,6 +72,35 @@
 #define MISSING_CASE(x) WARN(1, "Missing switch case (%lu) in %s\n", \
                              (long) (x), __func__);
 
+/* Use I915_STATE_WARN(x) and I915_STATE_WARN_ON() (rather than WARN() and
+ * WARN_ON()) for hw state sanity checks to check for unexpected conditions
+ * which may not necessarily be a user visible problem.  This will either
+ * WARN() or DRM_ERROR() depending on the verbose_checks moduleparam, to
+ * enable distros and users to tailor their preferred amount of i915 abrt
+ * spam.
+ */
+#define I915_STATE_WARN(condition, format...) ({                        \
+        int __ret_warn_on = !!(condition);                              \
+        if (unlikely(__ret_warn_on)) {                                  \
+                if (i915.verbose_state_checks)                          \
+                        __WARN_printf(format);                          \
+                else                                                    \
+                        DRM_ERROR(format);                              \
+        }                                                               \
+        unlikely(__ret_warn_on);                                        \
+})
+
+#define I915_STATE_WARN_ON(condition) ({                                \
+        int __ret_warn_on = !!(condition);                              \
+        if (unlikely(__ret_warn_on)) {                                  \
+                if (i915.verbose_state_checks)                          \
+                        __WARN_printf("WARN_ON(" #condition ")\n");     \
+                else                                                    \
+                        DRM_ERROR("WARN_ON(" #condition ")\n");         \
+        }                                                               \
+        unlikely(__ret_warn_on);                                        \
+})
+
 enum pipe {
         INVALID_PIPE = -1,
         PIPE_A = 0,
@@ -2401,6 +2430,7 @@ struct i915_params {
         bool disable_vtd_wa;
         int use_mmio_flip;
         bool mmio_debug;
+        bool verbose_state_checks;
 };
 extern struct i915_params i915 __read_mostly;