drm/nouveau/kms/nv50-: Add .blend_modes to nv50_wndw_func

At the moment, we currently (incorrectly) only expose a blend property on
the plane if we have a nv50_wndw_func->blend_set function for the given
wndw type. But we need to expose a blend property for all types of planes
that can display color formats with an alpha channel.

Prepare for doing this by introducing a way of looking up the supported
blend modes for a type of wndw by introducing .blend_modes, which describes
all possible blending modes nouveau currently supports for a type of wndw.

Signed-off-by: Lyude Paul <lyude@redhat.com>
Reviewed-by: Dave Airlie <airlied@redhat.com>
Fixes: 860e748bdd ("drm: ensure blend mode supported if pixel format with alpha exposed")
Link: https://patch.msgid.link/20260720215058.398210-2-lyude@redhat.com

drivers/gpu/drm/nouveau/dispnv50/base.h

@@ -1,5 +1,7 @@
 #ifndef __NV50_KMS_BASE_H__
 #define __NV50_KMS_BASE_H__
+#include <drm/drm_blend.h>
+
 #include "wndw.h"
 
 int base507c_new(struct nouveau_drm *, int, s32, struct nv50_wndw **);
@@ -24,4 +26,8 @@ extern const struct nv50_wndw_func base907c;
 int base917c_new(struct nouveau_drm *, int, s32, struct nv50_wndw **);
 
 int nv50_base_new(struct nouveau_drm *, int head, struct nv50_wndw **);
+
+/* The only blend mode supported by base channels */
+#define BASE_BLEND_MODES BIT(DRM_MODE_BLEND_PIXEL_NONE)
+
 #endif

drivers/gpu/drm/nouveau/dispnv50/base507c.c

@@ -297,6 +297,7 @@ base507c = {
 	.image_set = base507c_image_set,
 	.image_clr = base507c_image_clr,
 	.update = base507c_update,
+	.blend_modes = BASE_BLEND_MODES,
 };
 
 int

drivers/gpu/drm/nouveau/dispnv50/base827c.c

@@ -93,6 +93,7 @@ base827c = {
 	.image_set = base827c_image_set,
 	.image_clr = base507c_image_clr,
 	.update = base507c_update,
+	.blend_modes = BASE_BLEND_MODES,
 };
 
 int

drivers/gpu/drm/nouveau/dispnv50/base907c.c

@@ -205,6 +205,7 @@ base907c = {
 	.image_set = base907c_image_set,
 	.image_clr = base507c_image_clr,
 	.update = base507c_update,
+	.blend_modes = BASE_BLEND_MODES,
 };
 
 int

drivers/gpu/drm/nouveau/dispnv50/curs507a.c

@@ -29,6 +29,7 @@
 #include <nvhw/class/cl507a.h>
 
 #include <drm/drm_atomic_helper.h>
+#include <drm/drm_blend.h>
 #include <drm/drm_fourcc.h>
 
 bool
@@ -164,6 +165,8 @@ curs507a_wndw = {
 	.acquire = curs507a_acquire,
 	.release = curs507a_release,
 	.prepare = curs507a_prepare,
+	// TODO: Cursors also support premulti, but we haven't hooked it up anywhere yet.
+	.blend_modes = BIT(DRM_MODE_BLEND_COVERAGE),
 };
 
 int

drivers/gpu/drm/nouveau/dispnv50/wndw.h

@@ -1,6 +1,8 @@
 #ifndef __NV50_KMS_WNDW_H__
 #define __NV50_KMS_WNDW_H__
 #define nv50_wndw(p) container_of((p), struct nv50_wndw, plane)
+#include <drm/drm_blend.h>
+
 #include "disp.h"
 #include "atom.h"
 #include "lut.h"
@@ -74,6 +76,7 @@ struct nv50_wndw_func {
 	int (*image_clr)(struct nv50_wndw *);
 	int (*scale_set)(struct nv50_wndw *, struct nv50_wndw_atom *);
 	int (*blend_set)(struct nv50_wndw *, struct nv50_wndw_atom *);
+	unsigned int blend_modes;
 
 	int (*update)(struct nv50_wndw *, u32 *interlock);
 };
@@ -139,4 +142,11 @@ int wndwca7e_new(struct nouveau_drm *, enum drm_plane_type, int, s32,
 
 int nv50_wndw_new(struct nouveau_drm *, enum drm_plane_type, int index,
 		  struct nv50_wndw **);
+
+/* A set of blend modes supported by all wndws */
+#define WNDW_BLEND_MODES                \
+	(  BIT(DRM_MODE_BLEND_COVERAGE) \
+	 | BIT(DRM_MODE_BLEND_PREMULTI) \
+	 | BIT(DRM_MODE_BLEND_PIXEL_NONE))
+
 #endif

drivers/gpu/drm/nouveau/dispnv50/wndwc37e.c

@@ -343,6 +343,7 @@ wndwc37e = {
 	.image_set = wndwc37e_image_set,
 	.image_clr = wndwc37e_image_clr,
 	.blend_set = wndwc37e_blend_set,
+	.blend_modes = WNDW_BLEND_MODES,
 	.update = wndwc37e_update,
 };
 

drivers/gpu/drm/nouveau/dispnv50/wndwc57e.c

@@ -231,6 +231,7 @@ wndwc57e = {
 	.image_set = wndwc57e_image_set,
 	.image_clr = wndwc37e_image_clr,
 	.blend_set = wndwc37e_blend_set,
+	.blend_modes = WNDW_BLEND_MODES,
 	.update = wndwc37e_update,
 };
 

drivers/gpu/drm/nouveau/dispnv50/wndwc67e.c

@@ -95,6 +95,7 @@ wndwc67e = {
 	.image_set = wndwc67e_image_set,
 	.image_clr = wndwc37e_image_clr,
 	.blend_set = wndwc37e_blend_set,
+	.blend_modes = WNDW_BLEND_MODES,
 	.update = wndwc37e_update,
 };
 

drivers/gpu/drm/nouveau/dispnv50/wndwca7e.c

@@ -231,6 +231,7 @@ wndwca7e = {
 	.image_set = wndwca7e_image_set,
 	.image_clr = wndwca7e_image_clr,
 	.blend_set = wndwc37e_blend_set,
+	.blend_modes = WNDW_BLEND_MODES,
 	.update = wndwc37e_update,
 };