drm: introduce fb_modifiers_not_supported flag in mode_config

If only linear modifier is advertised, since there are many drivers that
only linear supported, the DRM core should handle this rather than
open-coding in every driver. However, there are legacy drivers such as
radeon that do not support modifiers but infer the actual layout of the
underlying buffer. Therefore, a new flag fb_modifiers_not_supported is
introduced for these legacy drivers, and allow_fb_modifiers is replaced
with this new flag.

v3:
 - change the order as follows:
   1. add fb_modifiers_not_supported flag
   2. add default modifiers
   3. remove allow_fb_modifiers flag
 - add a conditional disable in amdgpu_dm_plane_init()

v4:
 - modify kernel docs

v5:
 - modify kernel docs
Signed-off-by: Tomohito Esaki <etom@igel.co.jp>
Acked-by: Harry Wentland <harry.wentland@amd.com>
Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Link: https://patchwork.freedesktop.org/patch/msgid/20220128060836.11216-2-etom@igel.co.jp

drivers/gpu/drm/amd/amdgpu/amdgpu_display.c

@@ -956,7 +956,7 @@ static int amdgpu_display_verify_sizes(struct amdgpu_framebuffer *rfb)
 	int ret;
 	unsigned int i, block_width, block_height, block_size_log2;
 
-	if (!rfb->base.dev->mode_config.allow_fb_modifiers)
+	if (rfb->base.dev->mode_config.fb_modifiers_not_supported)
 		return 0;
 
 	for (i = 0; i < format_info->num_planes; ++i) {
@@ -1143,7 +1143,7 @@ int amdgpu_display_framebuffer_init(struct drm_device *dev,
 	if (ret)
 		return ret;
 
-	if (!dev->mode_config.allow_fb_modifiers) {
+	if (dev->mode_config.fb_modifiers_not_supported) {
 		drm_WARN_ONCE(dev, adev->family >= AMDGPU_FAMILY_AI,
 			      "GFX9+ requires FB check based on format modifier\n");
 		ret = check_tiling_flags_gfx6(rfb);
@@ -1151,7 +1151,7 @@ int amdgpu_display_framebuffer_init(struct drm_device *dev,
 			return ret;
 	}
 
-	if (dev->mode_config.allow_fb_modifiers &&
+	if (!dev->mode_config.fb_modifiers_not_supported &&
 	    !(rfb->base.flags & DRM_MODE_FB_MODIFIERS)) {
 		ret = convert_tiling_flags_to_modifier(rfb);
 		if (ret) {

drivers/gpu/drm/amd/amdgpu/dce_v10_0.c

@@ -2798,6 +2798,8 @@ static int dce_v10_0_sw_init(void *handle)
 	adev_to_drm(adev)->mode_config.preferred_depth = 24;
 	adev_to_drm(adev)->mode_config.prefer_shadow = 1;
 
+	adev_to_drm(adev)->mode_config.fb_modifiers_not_supported = true;
+
 	adev_to_drm(adev)->mode_config.fb_base = adev->gmc.aper_base;
 
 	r = amdgpu_display_modeset_create_props(adev);

drivers/gpu/drm/amd/amdgpu/dce_v11_0.c

@@ -2916,6 +2916,8 @@ static int dce_v11_0_sw_init(void *handle)
 	adev_to_drm(adev)->mode_config.preferred_depth = 24;
 	adev_to_drm(adev)->mode_config.prefer_shadow = 1;
 
+	adev_to_drm(adev)->mode_config.fb_modifiers_not_supported = true;
+
 	adev_to_drm(adev)->mode_config.fb_base = adev->gmc.aper_base;
 
 	r = amdgpu_display_modeset_create_props(adev);

drivers/gpu/drm/amd/amdgpu/dce_v6_0.c

@@ -2674,6 +2674,7 @@ static int dce_v6_0_sw_init(void *handle)
 	adev_to_drm(adev)->mode_config.max_height = 16384;
 	adev_to_drm(adev)->mode_config.preferred_depth = 24;
 	adev_to_drm(adev)->mode_config.prefer_shadow = 1;
+	adev_to_drm(adev)->mode_config.fb_modifiers_not_supported = true;
 	adev_to_drm(adev)->mode_config.fb_base = adev->gmc.aper_base;
 
 	r = amdgpu_display_modeset_create_props(adev);

drivers/gpu/drm/amd/amdgpu/dce_v8_0.c

@@ -2695,6 +2695,8 @@ static int dce_v8_0_sw_init(void *handle)
 	adev_to_drm(adev)->mode_config.preferred_depth = 24;
 	adev_to_drm(adev)->mode_config.prefer_shadow = 1;
 
+	adev_to_drm(adev)->mode_config.fb_modifiers_not_supported = true;
+
 	adev_to_drm(adev)->mode_config.fb_base = adev->gmc.aper_base;
 
 	r = amdgpu_display_modeset_create_props(adev);

drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c

@@ -7828,6 +7828,9 @@ static int amdgpu_dm_plane_init(struct amdgpu_display_manager *dm,
 	if (res)
 		return res;
 
+	if (modifiers == NULL)
+		adev_to_drm(dm->adev)->mode_config.fb_modifiers_not_supported = true;
+
 	res = drm_universal_plane_init(adev_to_drm(dm->adev), plane, possible_crtcs,
 				       &dm_plane_funcs, formats, num_formats,
 				       modifiers, plane->type, NULL);

drivers/gpu/drm/drm_framebuffer.c

@@ -309,7 +309,7 @@ drm_internal_framebuffer_create(struct drm_device *dev,
 	}
 
 	if (r->flags & DRM_MODE_FB_MODIFIERS &&
-	    !dev->mode_config.allow_fb_modifiers) {
+	    dev->mode_config.fb_modifiers_not_supported) {
 		DRM_DEBUG_KMS("driver does not support fb modifiers\n");
 		return ERR_PTR(-EINVAL);
 	}
@@ -594,7 +594,7 @@ int drm_mode_getfb2_ioctl(struct drm_device *dev,
 	r->pixel_format = fb->format->format;
 
 	r->flags = 0;
-	if (dev->mode_config.allow_fb_modifiers)
+	if (!dev->mode_config.fb_modifiers_not_supported)
 		r->flags |= DRM_MODE_FB_MODIFIERS;
 
 	for (i = 0; i < ARRAY_SIZE(r->handles); i++) {
@@ -607,7 +607,7 @@ int drm_mode_getfb2_ioctl(struct drm_device *dev,
 	for (i = 0; i < fb->format->num_planes; i++) {
 		r->pitches[i] = fb->pitches[i];
 		r->offsets[i] = fb->offsets[i];
-		if (dev->mode_config.allow_fb_modifiers)
+		if (!dev->mode_config.fb_modifiers_not_supported)
 			r->modifier[i] = fb->modifier;
 	}
 

drivers/gpu/drm/drm_ioctl.c

@@ -297,7 +297,7 @@ static int drm_getcap(struct drm_device *dev, void *data, struct drm_file *file_
 			req->value = 64;
 		break;
 	case DRM_CAP_ADDFB2_MODIFIERS:
-		req->value = dev->mode_config.allow_fb_modifiers;
+		req->value = !dev->mode_config.fb_modifiers_not_supported;
 		break;
 	case DRM_CAP_CRTC_IN_VBLANK_EVENT:
 		req->value = 1;

drivers/gpu/drm/nouveau/nouveau_display.c

@@ -708,11 +708,13 @@ nouveau_display_create(struct drm_device *dev)
 				     &disp->disp);
 		if (ret == 0) {
 			nouveau_display_create_properties(dev);
-			if (disp->disp.object.oclass < NV50_DISP)
+			if (disp->disp.object.oclass < NV50_DISP) {
+				dev->mode_config.fb_modifiers_not_supported = true;
 				ret = nv04_display_create(dev);
-			else
+			} else {
 				ret = nv50_display_create(dev);
 			}
+		}
 	} else {
 		ret = 0;
 	}

drivers/gpu/drm/radeon/radeon_display.c

@@ -1596,6 +1596,8 @@ int radeon_modeset_init(struct radeon_device *rdev)
 	rdev->ddev->mode_config.preferred_depth = 24;
 	rdev->ddev->mode_config.prefer_shadow = 1;
 
+	rdev->ddev->mode_config.fb_modifiers_not_supported = true;
+
 	rdev->ddev->mode_config.fb_base = rdev->mc.aper_base;
 
 	ret = radeon_modeset_create_props(rdev);

include/drm/drm_mode_config.h

@@ -933,6 +933,16 @@ struct drm_mode_config {
 	 */
 	bool allow_fb_modifiers;
 
+	/**
+	 * @fb_modifiers_not_supported:
+	 *
+	 * When this flag is set, the DRM device will not expose modifier
+	 * support to userspace. This is only used by legacy drivers that infer
+	 * the buffer layout through heuristics without using modifiers. New
+	 * drivers shall not set fhis flag.
+	 */
+	bool fb_modifiers_not_supported;
+
 	/**
 	 * @normalize_zpos:
 	 *