diff mbox series

[1/2] drm: mark CONFIG_DRM_USE_DYNAMIC_DEBUG as BROKEN for now

Message ID 20221205161005.222274-2-jim.cromie@gmail.com
State New
Headers
Series DRM - avoid regression in -rc, fix comment |

Commit Message

Jim Cromie Dec. 5, 2022, 4:10 p.m. UTC 
  CONFIG_DRM_USE_DYNAMIC_DEBUG=y has a regression, due to a chicken-egg
initialization problem:

1- modprobe i915
   i915 needs drm.ko, which is loaded 1st

2- "modprobe drm drm.debug=0x1ff" (virtual/implied)
   drm.debug is set post-initialization, from boot-args etc

3- `modprobe i915` finishes

W/O drm.debug-on-dyndbg that just works, because drm_dbg* does
drm_debug_enabled() to check __drm_debug & DRM_UT_<CAT> before
printing.

But the whole point of CONFIG_DRM_USE_DYNAMIC_DEBUG is to avoid that
runtime test, by enabling (at end/after module_init) a static-key at
selected callsites in the just-loaded module.

And since drm.ko is loaded before all dependent modules, no other
modules are "just-loaded", and their drm.debug callsites are not
present yet, just those in drm.ko itself.

CC: <ville.syrjala@linux.intel.com>
Signed-off-by: Jim Cromie <jim.cromie@gmail.com>
---
.v2 - default=N, cuz CI tests BROKEN stuff too. @ville.syrjala
---
 drivers/gpu/drm/Kconfig | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)
diff mbox series

Patch

diff --git a/drivers/gpu/drm/Kconfig b/drivers/gpu/drm/Kconfig
index 34f5a092c99e..5adc8d5b6a40 100644
--- a/drivers/gpu/drm/Kconfig
+++ b/drivers/gpu/drm/Kconfig
@@ -53,7 +53,8 @@  config DRM_DEBUG_MM
 
 config DRM_USE_DYNAMIC_DEBUG
 	bool "use dynamic debug to implement drm.debug"
-	default y
+	default n
+	depends on BROKEN	# chicken-egg initial enable problem
 	depends on DRM
 	depends on DYNAMIC_DEBUG || DYNAMIC_DEBUG_CORE
 	depends on JUMP_LABEL