drm: enable (most) W=1 warnings by default across the subsystem

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 <[email protected]>
Cc: Daniel Vetter <[email protected]>
Cc: Maarten Lankhorst <[email protected]>
Cc: Maxime Ripard <[email protected]>
Cc: Thomas Zimmermann <[email protected]>
Cc: Alex Deucher <[email protected]>
Cc: Christian König <[email protected]>
Cc: Pan
Cc: Karol Herbst <[email protected]>
Cc: Lyude Paul <[email protected]>
Cc: Rob Clark <[email protected]>
Cc: Abhinav Kumar <[email protected]>
Cc: Dmitry Baryshkov <[email protected]>
Cc: Sean Paul <[email protected]>
Cc: Marijn Suijten <[email protected]>
Cc: Hamza Mahfooz <[email protected]>
Acked-by: Javier Martinez Canillas <[email protected]>
Acked-by: Thomas Zimmermann <[email protected]>
Acked-by: Sui Jingfeng <[email protected]>
Acked-by: Danilo Krummrich <[email protected]>
Acked-by: Maxime Ripard <[email protected]>
Link: https://patchwork.freedesktop.org/patch/msgid/a50f1a69d5af72e913996179a75bc3a71d81ebea.1709629403.git.jani.nikula@intel.com
Signed-off-by: Jani Nikula <[email protected]>

diff --git a/drivers/gpu/drm/Makefile b/drivers/gpu/drm/Makefile
index 6eb2b553a163607adbf8ff77e5ffb0454129cff2..ea456f057e8a1c8713d2a1f18bbddc37cc2d2740 100644 (file)
--- 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 \