[PATCH] drm: Add DRM_NOTICE_IF

[Chris Wilson]

Styled after WARN_ON/DRM_ERROR_ON, this prints a mild warning message (a
KERN_NOTICE for significant but mild events) that allows us to insert
interesting events without alarming the user or bug reporting tools.

For an example I have changed a DRM_ERROR for being unable to set a
performance enhancement in i915.

Signed-off-by: Chris Wilson <chris at chris-wilson.co.uk>
---
 drivers/gpu/drm/i915/intel_lrc.c |  5 ++---
 include/drm/drmP.h               | 20 ++++++++++++++++++++
 2 files changed, 22 insertions(+), 3 deletions(-)

diff --git a/drivers/gpu/drm/i915/intel_lrc.c b/drivers/gpu/drm/i915/intel_lrc.c
index 184d5f2dce21..f62cd78f8691 100644
--- a/drivers/gpu/drm/i915/intel_lrc.c
+++ b/drivers/gpu/drm/i915/intel_lrc.c
@@ -1902,13 +1902,12 @@ static int gen8_init_rcs_context(struct drm_i915_gem_request *req)
 	if (ret)
 		return ret;
 
-	ret = intel_rcs_context_init_mocs(req);
 	/*
 	 * Failing to program the MOCS is non-fatal.The system will not
 	 * run at peak performance. So generate an error and carry on.
 	 */
-	if (ret)
-		DRM_ERROR("MOCS failed to program: expect performance issues.\n");
+	DRM_NOTICE_IF(intel_rcs_context_init_mocs(req),
+		      "MOCS failed to program: expect performance issues.\n");
 
 	return intel_lr_context_render_state_init(req);
 }
diff --git a/include/drm/drmP.h b/include/drm/drmP.h
index b76af322d812..f2d68d185274 100644
--- a/include/drm/drmP.h
+++ b/include/drm/drmP.h
@@ -181,6 +181,26 @@ void drm_err(const char *format, ...);
 })
 
 /**
+ * Mild warning on assertion-esque failure.
+ *
+ * \param cond condition on which to *fail*
+ * \param fmt printf() like format string.
+ * \param arg arguments
+ *
+ * This is similar to WARN_ON but only prints a NOTICE rather than a warning
+ * and the whole stacktrace. It is only intended for mild issues which
+ * while significant do not critically impact the user (such as a performance
+ * issue).
+ */
+#define DRM_NOTICE_IF(cond, fmt, ...) ({				\
+	bool __cond = !!(cond);						\
+	if (unlikely(__cond))						\
+		printk(KERN_NOTICE "[" DRM_NAME ":%s] " fmt,		\
+		       __func__, ##__VA_ARGS__);			\
+	unlikely(__cond);						\
+})
+
+/**
  * Rate limited error output.  Like DRM_ERROR() but won't flood the log.
  *
  * \param fmt printf() like format string.
-- 
2.4.6