[PATCH 2/7] drm_print: fixup improve stale comment

[Jim Cromie <jim.cromie@gmail.com>]

Cited commit uses stale macro name, fix this.  And improve the explanation.

When DRM_USE_DYNAMIC_DEBUG=y, DECLARE_DYNDBG_CLASSMAP() does the
mapping of DRM_UT_* onto BITs in drm.debug.  While this is still using
the drm_debug_category enum to do the mapping, its doing so somewhat
indirectly, with the ordered set of DRM_UT_* enum-vals.  This requires
that the macro args: DRM_UT_* list must be kept in sync.

fixes: f158936b60a7 (drm: POC drm on dyndbg - use in core, 2 helpers, 3 drivers.)
Signed-off-by: Jim Cromie <jim.cromie@gmail.com>
---
. emphasize ABI non-change despite enum val change - Jani
---
 include/drm/drm_print.h | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/include/drm/drm_print.h b/include/drm/drm_print.h
index a44fb7ef257f..06deb58d5af4 100644
--- a/include/drm/drm_print.h
+++ b/include/drm/drm_print.h
@@ -276,7 +276,10 @@ static inline struct drm_printer drm_err_printer(const char *prefix)
  *
  */
 enum drm_debug_category {
-	/* These names must match those in DYNAMIC_DEBUG_CLASSBITS */
+	/*
+	 * Keep DECLARE_DYNDBG_CLASSMAP args in sync with changes
+	 * here, the values define BIT()s in drm.debug, so are ABI.
+	 */
 	/**
 	 * @DRM_UT_CORE: Used in the generic drm code: drm_ioctl.c, drm_mm.c,
 	 * drm_memory.c, ...
-- 
2.38.1