drm/amd/amdgpu: introduce DRM_AMDGPU_WERROR

We want to do -Werror builds on our CI. However, non-amdgpu breakages
have prevented us from doing so thus far. Also, there are a number of
additional checks that we should enable, that the community cares about
and are hidden behind -Wextra. So, define DRM_AMDGPU_WERROR to only
enable -Werror for the amdgpu kernel module and enable -Wextra while
disabling all of the checks that are too noisy.

Cc: Alex Deucher <alexander.deucher@amd.com>
Cc: Kenny Ho <kenny.ho@amd.com>
Suggested-by: Jani Nikula <jani.nikula@linux.intel.com>
Reviewed-by: Kenny Ho <Kenny.Ho@amd.com>
Signed-off-by: Hamza Mahfooz <hamza.mahfooz@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

drivers/gpu/drm/amd/amdgpu/Kconfig

@@ -69,6 +69,16 @@ config DRM_AMDGPU_USERPTR
 	  This option selects CONFIG_HMM and CONFIG_HMM_MIRROR if it
 	  isn't already selected to enabled full userptr support.
 
+config DRM_AMDGPU_WERROR
+	bool "Force the compiler to throw an error instead of a warning when compiling"
+	depends on DRM_AMDGPU
+	depends on EXPERT
+	depends on !COMPILE_TEST
+	default n
+	help
+	  Add -Werror to the build flags for amdgpu.ko.
+	  Only enable this if you are warning code for amdgpu.ko.
+
 source "drivers/gpu/drm/amd/acp/Kconfig"
 source "drivers/gpu/drm/amd/display/Kconfig"
 source "drivers/gpu/drm/amd/amdkfd/Kconfig"

drivers/gpu/drm/amd/amdgpu/Makefile

@@ -39,6 +39,15 @@ ccflags-y := -I$(FULL_AMD_PATH)/include/asic_reg \
 	-I$(FULL_AMD_DISPLAY_PATH)/amdgpu_dm \
 	-I$(FULL_AMD_PATH)/amdkfd
 
+subdir-ccflags-y := -Wextra
+subdir-ccflags-y += -Wunused-but-set-variable
+subdir-ccflags-y += -Wno-unused-parameter
+subdir-ccflags-y += -Wno-type-limits
+subdir-ccflags-y += -Wno-sign-compare
+subdir-ccflags-y += -Wno-missing-field-initializers
+subdir-ccflags-y += -Wno-override-init
+subdir-ccflags-$(CONFIG_DRM_AMDGPU_WERROR) += -Werror
+
 amdgpu-y := amdgpu_drv.o
 
 # add KMS driver