linux-kernel - [PATCH v2 59/59] drm: RFC - make drm_dyndbg_user.o for drm-*

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Message-ID: <20250320185238.447458-60-jim.cromie@gmail.com>
Date: Thu, 20 Mar 2025 12:52:37 -0600
From: Jim Cromie <jim.cromie@...il.com>
To: linux-kernel@...r.kernel.org,
	dri-devel@...ts.freedesktop.org,
	amd-gfx@...ts.freedesktop.org,
	intel-gvt-dev@...ts.freedesktop.org,
	intel-gfx@...ts.freedesktop.org,
	intel-gfx-trybot@...ts.freedesktop.org
Cc: jbaron@...mai.com,
	gregkh@...uxfoundation.org,
	ukaszb@...omium.org,
	louis.chauvet@...tlin.com,
	daniel.vetter@...ll.ch,
	tvrtko.ursulin@...ux.intel.com,
	jani.nikula@...el.com,
	ville.syrjala@...ux.intel.com,
	Jim Cromie <jim.cromie@...il.com>
Subject: [PATCH v2 59/59] drm: RFC - make drm_dyndbg_user.o for drm-*_helpers, drivers

Add new drm_dyndbg_user.c with a single call to
DYNDBG_CLASSMAP_USE(drm_debug_classes).  This creates a _class_user
record (and a linkage dependency).

If a driver adds this object to its Makefile target, it gets the
record, which authorizes dyndbg to enable the module's class'd
pr_debugs, such as DRMs <category>_dbg() macros.

So Id like to automatically inject this object into drivers.  I tried
subdir-objs-y, but thats not a thing.

In drm/Makefile:

Add object dependency to drm_*_helper-y targets:

  $targ-$(CONFIG_DRM_USE_DYNAMIC_DEBUG) += drm_dyndbg_user.o

Attempt a foreach:

  to add $driver-y += ../drm_dyndbg_user.o

this appears to be a train-wreck for impl reasons, but it describes a
want/need reasonably well.  It might not be a good maintainble idea.

Explicitly adding to radeon/Makefile worked:

  $radeon-$(CONFIG_DRM_USE_DYNAMIC_DEBUG) += ../drm_dyndbg_user.o

But doing this is just as per-module as just adding the _USE()
explicitly to the main .c file, which is less magical than make-fu.

Also, it appears to cause make && make rebuilds.

and try to link it to helpers and everything

Signed-off-by: Jim Cromie <jim.cromie@...il.com>
---
 drivers/gpu/drm/Makefile          |  9 +++++++++
 drivers/gpu/drm/drm_dyndbg_user.c | 11 +++++++++++
 2 files changed, 20 insertions(+)
 create mode 100644 drivers/gpu/drm/drm_dyndbg_user.c

diff --git a/drivers/gpu/drm/Makefile b/drivers/gpu/drm/Makefile
index 704f94efc804..1adb5a262180 100644
--- a/drivers/gpu/drm/Makefile
+++ b/drivers/gpu/drm/Makefile
@@ -74,10 +74,12 @@ drm-y := \
 	drm_vblank_work.o \
 	drm_vma_manager.o \
 	drm_writeback.o
+
 drm-$(CONFIG_DRM_CLIENT) += \
 	drm_client.o \
 	drm_client_event.o \
 	drm_client_modeset.o
+
 drm-$(CONFIG_DRM_LIB_RANDOM) += lib/drm_random.o
 drm-$(CONFIG_COMPAT) += drm_ioc32.o
 drm-$(CONFIG_DRM_PANEL) += drm_panel.o
@@ -111,20 +113,25 @@ obj-$(CONFIG_DRM_BUDDY) += drm_buddy.o
 drm_dma_helper-y := drm_gem_dma_helper.o
 drm_dma_helper-$(CONFIG_DRM_FBDEV_EMULATION) += drm_fbdev_dma.o
 drm_dma_helper-$(CONFIG_DRM_KMS_HELPER) += drm_fb_dma_helper.o
+drm_dma_helper-$(CONFIG_DRM_USE_DYNAMIC_DEBUG) += drm_dyndbg_user.o
 obj-$(CONFIG_DRM_GEM_DMA_HELPER) += drm_dma_helper.o
 
 drm_shmem_helper-y := drm_gem_shmem_helper.o
 drm_shmem_helper-$(CONFIG_DRM_FBDEV_EMULATION) += drm_fbdev_shmem.o
+drm_shmem_helper-$(CONFIG_DRM_USE_DYNAMIC_DEBUG) += drm_dyndbg_user.o
 obj-$(CONFIG_DRM_GEM_SHMEM_HELPER) += drm_shmem_helper.o
 
 drm_suballoc_helper-y := drm_suballoc.o
+drm_suballoc_helper-$(CONFIG_DRM_USE_DYNAMIC_DEBUG) += drm_dyndbg_user.o
 obj-$(CONFIG_DRM_SUBALLOC_HELPER) += drm_suballoc_helper.o
 
 drm_vram_helper-y := drm_gem_vram_helper.o
+drm_vram_helper-$(CONFIG_DRM_USE_DYNAMIC_DEBUG) += drm_dyndbg_user.o
 obj-$(CONFIG_DRM_VRAM_HELPER) += drm_vram_helper.o
 
 drm_ttm_helper-y := drm_gem_ttm_helper.o
 drm_ttm_helper-$(CONFIG_DRM_FBDEV_EMULATION) += drm_fbdev_ttm.o
+drm_ttm_helper-$(CONFIG_DRM_USE_DYNAMIC_DEBUG) += drm_dyndbg_user.o
 obj-$(CONFIG_DRM_TTM_HELPER) += drm_ttm_helper.o
 
 #
@@ -149,11 +156,13 @@ drm_kms_helper-y := \
 	drm_simple_kms_helper.o
 drm_kms_helper-$(CONFIG_DRM_PANEL_BRIDGE) += bridge/panel.o
 drm_kms_helper-$(CONFIG_DRM_FBDEV_EMULATION) += drm_fb_helper.o
+drm_kms_helper-$(CONFIG_DRM_USE_DYNAMIC_DEBUG) += drm_dyndbg_user.o
 obj-$(CONFIG_DRM_KMS_HELPER) += drm_kms_helper.o
 
 #
 # Drivers and the rest
 #
+subdir-obj-$(CONFIG_DRM_USE_DYNAMIC_DEBUG) += drm_dyndbg_user.o
 
 obj-y			+= tests/
 
diff --git a/drivers/gpu/drm/drm_dyndbg_user.c b/drivers/gpu/drm/drm_dyndbg_user.c
new file mode 100644
index 000000000000..9e4aa87d4b58
--- /dev/null
+++ b/drivers/gpu/drm/drm_dyndbg_user.c
@@ -0,0 +1,11 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+
+#include "drm/drm_print.h"
+/*
+ * if DRM_USE_DYNAMIC_DEBBUG:
+ *    DYNDBG_CLASSMAP_USE(drm_debug_classes);
+ *
+ * dyndbg classmaps are opt-in, so modules which call drm:_*_dbg must
+ * link this to authorize dyndbg to change the static-keys underneath.
+ */
+DRM_CLASSMAP_USE(drm_debug_classes);
-- 
2.49.0