Revert "drm/i915: use localized __diag_ignore_all() instead of per file"

This reverts commit 88e96644.

__diag_ignore_all() only works for GCC 8 or later.

-Woverride-init (from -Wextra, enabled in i915 Makefile) combined with
CONFIG_WERROR=y or W=e breaks the build for older GCC.

With i386_defconfig and x86_64_defconfig enabling CONFIG_WERROR=y by
default, we really need to roll back the change.

An alternative would be to disable -Woverride-init in the Makefile for
GCC <8, but the revert seems like the safest bet now.

Closes: https://gitlab.freedesktop.org/drm/intel/-/issues/8768Reported-by: John Garry <john.g.garry@oracle.com>
References: https://lore.kernel.org/r/ad2601c0-84bb-c574-3702-a83ff8faf98c@oracle.com
References: https://lore.kernel.org/r/87wmzezns4.fsf@intel.com
Fixes: 88e96644 ("drm/i915: use localized __diag_ignore_all() instead of per file")
Cc: Gustavo Sousa <gustavo.sousa@intel.com>
Cc: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>
Cc: Rodrigo Vivi <rodrigo.vivi@intel.com>
Cc: Tvrtko Ursulin <tvrtko.ursulin@linux.intel.com>
Signed-off-by: Jani Nikula <jani.nikula@intel.com>
Reviewed-by: Gustavo Sousa <gustavo.sousa@intel.com>
Tested-by: John Garry <john.g.garry@oracle.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20230711110214.25093-1-jani.nikula@intel.com

drivers/gpu/drm/i915/Makefile

@@ -23,6 +23,11 @@ subdir-ccflags-y += $(call cc-option, -Wunused-but-set-variable)
 subdir-ccflags-y += $(call cc-disable-warning, frame-address)
 subdir-ccflags-$(CONFIG_DRM_I915_WERROR) += -Werror
 
+# Fine grained warnings disable
+CFLAGS_i915_pci.o = $(call cc-disable-warning, override-init)
+CFLAGS_display/intel_display_device.o = $(call cc-disable-warning, override-init)
+CFLAGS_display/intel_fbdev.o = $(call cc-disable-warning, override-init)
+
 subdir-ccflags-y += -I$(srctree)/$(src)
 
 # Please keep these build lists sorted!

drivers/gpu/drm/i915/display/intel_display_device.c

@@ -16,9 +16,6 @@
 #include "intel_display_reg_defs.h"
 #include "intel_fbc.h"
 
-__diag_push();
-__diag_ignore_all("-Woverride-init", "Allow overriding inherited members");
-
 static const struct intel_display_device_info no_display = {};
 
 #define PIPE_A_OFFSET		0x70000
@@ -727,8 +724,6 @@ static const struct intel_display_device_info xe_lpdp_display = {
 		BIT(PORT_TC1) | BIT(PORT_TC2) | BIT(PORT_TC3) | BIT(PORT_TC4),
 };
 
-__diag_pop();
-
 #undef INTEL_VGA_DEVICE
 #undef INTEL_QUANTA_VGA_DEVICE
 #define INTEL_VGA_DEVICE(id, info) { id, info }

drivers/gpu/drm/i915/display/intel_fbdev.c

@@ -135,9 +135,6 @@ static int intel_fbdev_mmap(struct fb_info *info, struct vm_area_struct *vma)
 	return i915_gem_fb_mmap(obj, vma);
 }
 
-__diag_push();
-__diag_ignore_all("-Woverride-init", "Allow overriding the default ops");
-
 static const struct fb_ops intelfb_ops = {
 	.owner = THIS_MODULE,
 	__FB_DEFAULT_DEFERRED_OPS_RDWR(intel_fbdev),
@@ -149,8 +146,6 @@ static const struct fb_ops intelfb_ops = {
 	.fb_mmap = intel_fbdev_mmap,
 };
 
-__diag_pop();
-
 static int intelfb_alloc(struct drm_fb_helper *helper,
 			 struct drm_fb_helper_surface_size *sizes)
 {

drivers/gpu/drm/i915/i915_pci.c

@@ -38,9 +38,6 @@
 #include "i915_reg.h"
 #include "intel_pci_config.h"
 
-__diag_push();
-__diag_ignore_all("-Woverride-init", "Allow overriding inherited members");
-
 #define PLATFORM(x) .platform = (x)
 #define GEN(x) \
 	.__runtime.graphics.ip.ver = (x), \
@@ -846,8 +843,6 @@ static const struct intel_device_info mtl_info = {
 
 #undef PLATFORM
 
-__diag_pop();
-
 /*
  * Make sure any device matches here are from most specific to most
  * general.  For example, since the Quanta match is based on the subsystem