drm/cirrus: Move vmap out of commit tail

Vmap operations may acquire the dmabuf reservation lock, which is not
allowed within atomic commit-tail functions. Therefore move vmap and
vunmap from the damage handler into prepare_fb and cleanup_fb callbacks.

The mapping is provided as GEM shadow-buffered plane. The functions in
the commit tail use the pre-established mapping for damage handling.
Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de>
Tested-by: Gerd Hoffmann <kraxel@redhat.com>
Acked-by: Gerd Hoffmann <kraxel@redhat.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20210208115538.6430-6-tzimmermann@suse.de

drivers/gpu/drm/tiny/cirrus.c

@@ -33,8 +33,9 @@
 #include <drm/drm_file.h>
 #include <drm/drm_format_helper.h>
 #include <drm/drm_fourcc.h>
-#include <drm/drm_gem_shmem_helper.h>
+#include <drm/drm_gem_atomic_helper.h>
 #include <drm/drm_gem_framebuffer_helper.h>
+#include <drm/drm_gem_shmem_helper.h>
 #include <drm/drm_ioctl.h>
 #include <drm/drm_managed.h>
 #include <drm/drm_modeset_helper_vtables.h>
@@ -311,22 +312,15 @@ static int cirrus_mode_set(struct cirrus_device *cirrus,
 	return 0;
 }
 
-static int cirrus_fb_blit_rect(struct drm_framebuffer *fb,
+static int cirrus_fb_blit_rect(struct drm_framebuffer *fb, const struct dma_buf_map *map,
 			       struct drm_rect *rect)
 {
 	struct cirrus_device *cirrus = to_cirrus(fb->dev);
-	struct dma_buf_map map;
-	void *vmap;
-	int idx, ret;
+	void *vmap = map->vaddr; /* TODO: Use mapping abstraction properly */
+	int idx;
 
-	ret = -ENODEV;
 	if (!drm_dev_enter(&cirrus->dev, &idx))
-		goto out;
-
-	ret = drm_gem_shmem_vmap(fb->obj[0], &map);
-	if (ret)
-		goto out_dev_exit;
-	vmap = map.vaddr; /* TODO: Use mapping abstraction properly */
+		return -ENODEV;
 
 	if (cirrus->cpp == fb->format->cpp[0])
 		drm_fb_memcpy_dstclip(cirrus->vram,
@@ -345,16 +339,12 @@ static int cirrus_fb_blit_rect(struct drm_framebuffer *fb,
 	else
 		WARN_ON_ONCE("cpp mismatch");
 
-	drm_gem_shmem_vunmap(fb->obj[0], &map);
-	ret = 0;
-
-out_dev_exit:
 	drm_dev_exit(idx);
-out:
-	return ret;
+
+	return 0;
 }
 
-static int cirrus_fb_blit_fullscreen(struct drm_framebuffer *fb)
+static int cirrus_fb_blit_fullscreen(struct drm_framebuffer *fb, const struct dma_buf_map *map)
 {
 	struct drm_rect fullscreen = {
 		.x1 = 0,
@@ -362,7 +352,7 @@ static int cirrus_fb_blit_fullscreen(struct drm_framebuffer *fb)
 		.y1 = 0,
 		.y2 = fb->height,
 	};
-	return cirrus_fb_blit_rect(fb, &fullscreen);
+	return cirrus_fb_blit_rect(fb, map, &fullscreen);
 }
 
 static int cirrus_check_size(int width, int height,
@@ -441,9 +431,10 @@ static void cirrus_pipe_enable(struct drm_simple_display_pipe *pipe,
 			       struct drm_plane_state *plane_state)
 {
 	struct cirrus_device *cirrus = to_cirrus(pipe->crtc.dev);
+	struct drm_shadow_plane_state *shadow_plane_state = to_drm_shadow_plane_state(plane_state);
 
 	cirrus_mode_set(cirrus, &crtc_state->mode, plane_state->fb);
-	cirrus_fb_blit_fullscreen(plane_state->fb);
+	cirrus_fb_blit_fullscreen(plane_state->fb, &shadow_plane_state->map[0]);
 }
 
 static void cirrus_pipe_update(struct drm_simple_display_pipe *pipe,
@@ -451,16 +442,15 @@ static void cirrus_pipe_update(struct drm_simple_display_pipe *pipe,
 {
 	struct cirrus_device *cirrus = to_cirrus(pipe->crtc.dev);
 	struct drm_plane_state *state = pipe->plane.state;
+	struct drm_shadow_plane_state *shadow_plane_state = to_drm_shadow_plane_state(state);
 	struct drm_crtc *crtc = &pipe->crtc;
 	struct drm_rect rect;
 
-	if (pipe->plane.state->fb &&
-	    cirrus->cpp != cirrus_cpp(pipe->plane.state->fb))
-		cirrus_mode_set(cirrus, &crtc->mode,
-				pipe->plane.state->fb);
+	if (state->fb && cirrus->cpp != cirrus_cpp(state->fb))
+		cirrus_mode_set(cirrus, &crtc->mode, state->fb);
 
 	if (drm_atomic_helper_damage_merged(old_state, state, &rect))
-		cirrus_fb_blit_rect(pipe->plane.state->fb, &rect);
+		cirrus_fb_blit_rect(state->fb, &shadow_plane_state->map[0], &rect);
 }
 
 static const struct drm_simple_display_pipe_funcs cirrus_pipe_funcs = {
@@ -468,6 +458,7 @@ static const struct drm_simple_display_pipe_funcs cirrus_pipe_funcs = {
 	.check	    = cirrus_pipe_check,
 	.enable	    = cirrus_pipe_enable,
 	.update	    = cirrus_pipe_update,
+	DRM_GEM_SIMPLE_DISPLAY_PIPE_SHADOW_PLANE_FUNCS,
 };
 
 static const uint32_t cirrus_formats[] = {