[RESEND,v3,1/2] drm: enable (most) W=1 warnings by default across the subsystem

Commit Message

Jani Nikula March 5, 2024, 9:07 a.m. UTC

At least the i915 and amd drivers enable a bunch more compiler warnings
than the kernel defaults.

Extend most of the W=1 warnings to the entire drm subsystem by
default. Use the copy-pasted warnings from scripts/Makefile.extrawarn
with s/KBUILD_CFLAGS/subdir-ccflags-y/ to make it easier to compare and
keep up with them in the future.

This is similar to the approach currently used in i915.

Some of the -Wextra warnings do need to be disabled, just like in
Makefile.extrawarn, but take care to not disable them for W=2 or W=3
builds, depending on the warning.

There are too many -Wformat-truncation warnings to cleanly fix up front;
leave that warning disabled for now.

v3:
- Drop -Wmissing-declarations (already enabled by default)
- Drop -Wmissing-prototypes (already enabled by default)

v2:
- Drop -Wformat-truncation (too many warnings)
- Drop -Wstringop-overflow (already enabled by default)

Cc: David Airlie <[e-mail]>
Cc: Daniel Vetter <[e-mail]>
Cc: Maarten Lankhorst <[e-mail]>
Cc: Maxime Ripard <[e-mail]>
Cc: Thomas Zimmermann <[e-mail]>
Cc: Alex Deucher <[e-mail]>
Cc: Christian König <[e-mail]>
Cc: Pan, Xinhui <[e-mail]>
Cc: Karol Herbst <[e-mail]>
Cc: Lyude Paul <[e-mail]>
Cc: Rob Clark <[e-mail]>
Cc: Abhinav Kumar <[e-mail]>
Cc: Dmitry Baryshkov <[e-mail]>
Cc: Sean Paul <[e-mail]>
Cc: Marijn Suijten <[e-mail]>
Cc: Hamza Mahfooz <[e-mail]>
Acked-by: Javier Martinez Canillas <[e-mail]>
Acked-by: Thomas Zimmermann <[e-mail]>
Acked-by: Sui Jingfeng <[e-mail]>
Acked-by: Danilo Krummrich <[e-mail]>
Signed-off-by: Jani Nikula <[e-mail]>
---
 drivers/gpu/drm/Makefile | 25 +++++++++++++++++++++++++
 1 file changed, 25 insertions(+)

Patch

diff --git a/drivers/gpu/drm/Makefile b/drivers/gpu/drm/Makefile
index 6eb2b553a163..ea456f057e8a 100644
--- a/drivers/gpu/drm/Makefile
+++ b/drivers/gpu/drm/Makefile
@@ -5,6 +5,31 @@ 
 
 CFLAGS-$(CONFIG_DRM_USE_DYNAMIC_DEBUG)	+= -DDYNAMIC_DEBUG_MODULE
 
+# Unconditionally enable W=1 warnings locally
+# --- begin copy-paste W=1 warnings from scripts/Makefile.extrawarn
+subdir-ccflags-y += -Wextra -Wunused -Wno-unused-parameter
+subdir-ccflags-y += $(call cc-option, -Wrestrict)
+subdir-ccflags-y += -Wmissing-format-attribute
+subdir-ccflags-y += -Wold-style-definition
+subdir-ccflags-y += -Wmissing-include-dirs
+subdir-ccflags-y += $(call cc-option, -Wunused-but-set-variable)
+subdir-ccflags-y += $(call cc-option, -Wunused-const-variable)
+subdir-ccflags-y += $(call cc-option, -Wpacked-not-aligned)
+subdir-ccflags-y += $(call cc-option, -Wformat-overflow)
+# FIXME: fix -Wformat-truncation warnings and uncomment
+#subdir-ccflags-y += $(call cc-option, -Wformat-truncation)
+subdir-ccflags-y += $(call cc-option, -Wstringop-truncation)
+# The following turn off the warnings enabled by -Wextra
+ifeq ($(findstring 2, $(KBUILD_EXTRA_WARN)),)
+subdir-ccflags-y += -Wno-missing-field-initializers
+subdir-ccflags-y += -Wno-type-limits
+subdir-ccflags-y += -Wno-shift-negative-value
+endif
+ifeq ($(findstring 3, $(KBUILD_EXTRA_WARN)),)
+subdir-ccflags-y += -Wno-sign-compare
+endif
+# --- end copy-paste
+
 drm-y := \
 	drm_aperture.o \
 	drm_atomic.o \