drm/ast: Move cursor format conversion into helper function

Move the format conversion of the cursor framebuffer into the new
helper ast_cursor_plane_get_argb4444(). It returns a buffer in system
memory, which the atomic_update handler copies to video memory.

The returned buffer is either the GEM buffer itself, or a temporary
copy within the plane in ARGB4444 format.

As a small change, list supported formats explicitly in the switch
statement. Do not assume ARGB8888 input by default. The cursor
framebuffer knows its format, so should we.

Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de>
Reviewed-by: Jocelyn Falempe <jfalempe@redhat.com>
Link: https://patch.msgid.link/20251126094626.41985-2-tzimmermann@suse.de

1 files changed, 39 insertions, 23 deletions

diff --git a/drivers/gpu/drm/ast/ast_cursor.c b/drivers/gpu/drm/ast/ast_cursor.c
index 2d3ad7610c2e..24d696df8fcd 100644
--- a/drivers/gpu/drm/ast/ast_cursor.c
+++ b/drivers/gpu/drm/ast/ast_cursor.c
@@ -181,6 +181,38 @@ static int ast_cursor_plane_helper_atomic_check(struct drm_plane *plane,
 	return 0;
 }
 
+static const u8 *ast_cursor_plane_get_argb4444(struct ast_cursor_plane *ast_cursor_plane,
+					       struct drm_shadow_plane_state *shadow_plane_state,
+					       const struct drm_rect *clip)
+{
+	struct drm_plane_state *plane_state = &shadow_plane_state->base;
+	struct drm_framebuffer *fb = plane_state->fb;
+	u8 *argb4444 = NULL;
+
+	switch (fb->format->format) {
+	case DRM_FORMAT_ARGB4444:
+		argb4444 = shadow_plane_state->data[0].vaddr;
+		break;
+	case DRM_FORMAT_ARGB8888:
+		{
+			struct iosys_map argb4444_dst[DRM_FORMAT_MAX_PLANES] = {
+				IOSYS_MAP_INIT_VADDR(ast_cursor_plane->argb4444),
+			};
+			unsigned int argb4444_dst_pitch[DRM_FORMAT_MAX_PLANES] = {
+				AST_HWC_PITCH,
+			};
+
+			drm_fb_argb8888_to_argb4444(argb4444_dst, argb4444_dst_pitch,
+						    shadow_plane_state->data, fb, clip,
+						    &shadow_plane_state->fmtcnv_state);
+			argb4444 = argb4444_dst[0].vaddr;
+		}
+		break;
+	}
+
+	return argb4444;
+}
+
 static void ast_cursor_plane_helper_atomic_update(struct drm_plane *plane,
 						  struct drm_atomic_state *state)
 {
@@ -205,29 +237,13 @@ static void ast_cursor_plane_helper_atomic_update(struct drm_plane *plane,
 	 */
 
 	if (drm_atomic_helper_damage_merged(old_plane_state, plane_state, &damage)) {
-		u8 *argb4444;
-
-		switch (fb->format->format) {
-		case DRM_FORMAT_ARGB4444:
-			argb4444 = shadow_plane_state->data[0].vaddr;
-			break;
-		default:
-			argb4444 = ast_cursor_plane->argb4444;
-			{
-				struct iosys_map argb4444_dst[DRM_FORMAT_MAX_PLANES] = {
-					IOSYS_MAP_INIT_VADDR(argb4444),
-				};
-				unsigned int argb4444_dst_pitch[DRM_FORMAT_MAX_PLANES] = {
-					AST_HWC_PITCH,
-				};
-
-				drm_fb_argb8888_to_argb4444(argb4444_dst, argb4444_dst_pitch,
-							    shadow_plane_state->data, fb, &damage,
-							    &shadow_plane_state->fmtcnv_state);
-			}
-			break;
-		}
-		ast_set_cursor_image(ast, argb4444, fb->width, fb->height);
+		const u8 *argb4444 = ast_cursor_plane_get_argb4444(ast_cursor_plane,
+								   shadow_plane_state,
+								   &damage);
+
+		if (argb4444)
+			ast_set_cursor_image(ast, argb4444, fb->width, fb->height);
+
 		ast_set_cursor_base(ast, dst_off);
 	}