drm/ast: Convert ast to SHMEM

Replace GEM VRAM helpers with GEM SHMEM helpers in ast. Avoids OOM
errors when allocating video memory. Also adds support for dma-buf
functionality.

Aspeed display hardware supports display resolutions of FullHD and
higher at 32-bit pixel depth. But the amount of video memory is in
the range of 8 MiB to 32 MiB, which adds constraints to the actually
available resolutions. As atomic modesetting with VRAM helpers
requires double buffering in video memory, ast fails to pageflip
in some configurations. For example, FullHD with an active cursor
plane does not work on devices with 16 MiB of video memory.

Resolve this problem by converting the ast driver to GEM SHMEM helpers.
Keep the buffer objects in system memory and copy to video memory
on pageflips via shadow-plane helpers. Userspace used to require shadow
planes for decent performance, but that's now provided by the driver.
To replace the memory management, the patch also implements damage
handling for the primary plane.

With GEM SHMEM helpers, dma-buf import and export is now supported
by ast. This allows easier screen mirroring across devices or with
an Aspeed-based BMC. A corresponding feature request is available
at [1].

v2:
	* fix typos in commit message (Jocelyn)

Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de>
Reviewed-by: Jocelyn Falempe <jfalempe@redhat.com>
Tested-by: Jocelyn Falempe <jfalempe@redhat.com>
Link: https://lore.kernel.org/dri-devel/20220901124451.2523077-1-oushixiong@kylinos.cn/ # [1]
Link: https://patchwork.freedesktop.org/patch/msgid/20221013112923.769-8-tzimmermann@suse.de

1 files changed, 108 insertions, 96 deletions

diff --git a/drivers/gpu/drm/ast/ast_mode.c b/drivers/gpu/drm/ast/ast_mode.c
index 59c70fd5b925..1b991658290b 100644
--- a/drivers/gpu/drm/ast/ast_mode.c
+++ b/drivers/gpu/drm/ast/ast_mode.c
@@ -36,11 +36,13 @@
 #include <drm/drm_atomic_state_helper.h>
 #include <drm/drm_crtc.h>
 #include <drm/drm_crtc_helper.h>
+#include <drm/drm_damage_helper.h>
 #include <drm/drm_edid.h>
+#include <drm/drm_format_helper.h>
 #include <drm/drm_fourcc.h>
 #include <drm/drm_gem_atomic_helper.h>
 #include <drm/drm_gem_framebuffer_helper.h>
-#include <drm/drm_gem_vram_helper.h>
+#include <drm/drm_gem_shmem_helper.h>
 #include <drm/drm_managed.h>
 #include <drm/drm_probe_helper.h>
 #include <drm/drm_simple_kms_helper.h>
@@ -566,6 +568,29 @@ static void ast_wait_for_vretrace(struct ast_private *ast)
 }
 
 /*
+ * Planes
+ */
+
+static int ast_plane_init(struct drm_device *dev, struct ast_plane *ast_plane,
+			  void __iomem *vaddr, u64 offset, unsigned long size,
+			  uint32_t possible_crtcs,
+			  const struct drm_plane_funcs *funcs,
+			  const uint32_t *formats, unsigned int format_count,
+			  const uint64_t *format_modifiers,
+			  enum drm_plane_type type)
+{
+	struct drm_plane *plane = &ast_plane->base;
+
+	ast_plane->vaddr = vaddr;
+	ast_plane->offset = offset;
+	ast_plane->size = size;
+
+	return drm_universal_plane_init(dev, plane, possible_crtcs, funcs,
+					formats, format_count, format_modifiers,
+					type, NULL);
+}
+
+/*
  * Primary plane
  */
 
@@ -607,17 +632,29 @@ static int ast_primary_plane_helper_atomic_check(struct drm_plane *plane,
 	return 0;
 }
 
+static void ast_handle_damage(struct ast_plane *ast_plane, struct iosys_map *src,
+			      struct drm_framebuffer *fb,
+			      const struct drm_rect *clip)
+{
+	struct iosys_map dst = IOSYS_MAP_INIT_VADDR(ast_plane->vaddr);
+
+	iosys_map_incr(&dst, drm_fb_clip_offset(fb->pitches[0], fb->format, clip));
+	drm_fb_memcpy(&dst, fb->pitches, src, fb, clip);
+}
+
 static void ast_primary_plane_helper_atomic_update(struct drm_plane *plane,
 						   struct drm_atomic_state *state)
 {
 	struct drm_device *dev = plane->dev;
 	struct ast_private *ast = to_ast_private(dev);
 	struct drm_plane_state *plane_state = drm_atomic_get_new_plane_state(state, plane);
+	struct drm_shadow_plane_state *shadow_plane_state = to_drm_shadow_plane_state(plane_state);
 	struct drm_framebuffer *fb = plane_state->fb;
 	struct drm_plane_state *old_plane_state = drm_atomic_get_old_plane_state(state, plane);
 	struct drm_framebuffer *old_fb = old_plane_state->fb;
-	struct drm_gem_vram_object *gbo;
-	s64 gpu_addr;
+	struct ast_plane *ast_plane = to_ast_plane(plane);
+	struct drm_rect damage;
+	struct drm_atomic_helper_damage_iter iter;
 
 	if (!old_fb || (fb->format != old_fb->format)) {
 		struct drm_crtc *crtc = plane_state->crtc;
@@ -629,13 +666,13 @@ static void ast_primary_plane_helper_atomic_update(struct drm_plane *plane,
 		ast_set_vbios_color_reg(ast, fb->format, vbios_mode_info);
 	}
 
-	gbo = drm_gem_vram_of_gem(fb->obj[0]);
-	gpu_addr = drm_gem_vram_offset(gbo);
-	if (drm_WARN_ON_ONCE(dev, gpu_addr < 0))
-		return; /* Bug: we didn't pin the BO to VRAM in prepare_fb. */
+	drm_atomic_helper_damage_iter_init(&iter, old_plane_state, plane_state);
+	drm_atomic_for_each_plane_damage(&iter, &damage) {
+		ast_handle_damage(ast_plane, shadow_plane_state->data, fb, &damage);
+	}
 
 	ast_set_offset_reg(ast, fb);
-	ast_set_start_address_crt1(ast, (u32)gpu_addr);
+	ast_set_start_address_crt1(ast, (u32)ast_plane->offset);
 
 	ast_set_index_reg_mask(ast, AST_IO_SEQ_PORT, 0x1, 0xdf, 0x00);
 }
@@ -649,7 +686,7 @@ static void ast_primary_plane_helper_atomic_disable(struct drm_plane *plane,
 }
 
 static const struct drm_plane_helper_funcs ast_primary_plane_helper_funcs = {
-	DRM_GEM_VRAM_PLANE_HELPER_FUNCS,
+	DRM_GEM_SHADOW_PLANE_HELPER_FUNCS,
 	.atomic_check = ast_primary_plane_helper_atomic_check,
 	.atomic_update = ast_primary_plane_helper_atomic_update,
 	.atomic_disable = ast_primary_plane_helper_atomic_disable,
@@ -659,27 +696,30 @@ static const struct drm_plane_funcs ast_primary_plane_funcs = {
 	.update_plane = drm_atomic_helper_update_plane,
 	.disable_plane = drm_atomic_helper_disable_plane,
 	.destroy = drm_plane_cleanup,
-	.reset = drm_atomic_helper_plane_reset,
-	.atomic_duplicate_state = drm_atomic_helper_plane_duplicate_state,
-	.atomic_destroy_state = drm_atomic_helper_plane_destroy_state,
+	DRM_GEM_SHADOW_PLANE_FUNCS,
 };
 
 static int ast_primary_plane_init(struct ast_private *ast)
 {
 	struct drm_device *dev = &ast->base;
-	struct drm_plane *primary_plane = &ast->primary_plane;
+	struct ast_plane *ast_primary_plane = &ast->primary_plane;
+	struct drm_plane *primary_plane = &ast_primary_plane->base;
+	void __iomem *vaddr = ast->vram;
+	u64 offset = ast->vram_base;
+	unsigned long cursor_size = roundup(AST_HWC_SIZE + AST_HWC_SIGNATURE_SIZE, PAGE_SIZE);
+	unsigned long size = ast->vram_fb_available - cursor_size;
 	int ret;
 
-	ret = drm_universal_plane_init(dev, primary_plane, 0x01,
-				       &ast_primary_plane_funcs,
-				       ast_primary_plane_formats,
-				       ARRAY_SIZE(ast_primary_plane_formats),
-				       NULL, DRM_PLANE_TYPE_PRIMARY, NULL);
+	ret = ast_plane_init(dev, ast_primary_plane, vaddr, offset, size,
+			     0x01, &ast_primary_plane_funcs,
+			     ast_primary_plane_formats, ARRAY_SIZE(ast_primary_plane_formats),
+			     NULL, DRM_PLANE_TYPE_PRIMARY);
 	if (ret) {
-		drm_err(dev, "drm_universal_plane_init() failed: %d\n", ret);
+		drm_err(dev, "ast_plane_init() failed: %d\n", ret);
 		return ret;
 	}
 	drm_plane_helper_add(primary_plane, &ast_primary_plane_helper_funcs);
+	drm_plane_enable_fb_damage_clips(primary_plane);
 
 	return 0;
 }
@@ -828,31 +868,26 @@ static void ast_cursor_plane_helper_atomic_update(struct drm_plane *plane,
 	struct drm_shadow_plane_state *shadow_plane_state = to_drm_shadow_plane_state(plane_state);
 	struct drm_framebuffer *fb = plane_state->fb;
 	struct drm_plane_state *old_plane_state = drm_atomic_get_old_plane_state(state, plane);
-	struct drm_framebuffer *old_fb = old_plane_state->fb;
 	struct ast_private *ast = to_ast_private(plane->dev);
-	struct iosys_map dst_map = ast_plane->map;
-	u64 dst_off = ast_plane->off;
 	struct iosys_map src_map = shadow_plane_state->data[0];
+	struct drm_rect damage;
+	const u8 *src = src_map.vaddr; /* TODO: Use mapping abstraction properly */
+	u64 dst_off = ast_plane->offset;
+	u8 __iomem *dst = ast_plane->vaddr; /* TODO: Use mapping abstraction properly */
+	u8 __iomem *sig = dst + AST_HWC_SIZE; /* TODO: Use mapping abstraction properly */
 	unsigned int offset_x, offset_y;
 	u16 x, y;
 	u8 x_offset, y_offset;
-	u8 __iomem *dst;
-	u8 __iomem *sig;
-	const u8 *src;
-
-	src = src_map.vaddr; /* TODO: Use mapping abstraction properly */
-	dst = dst_map.vaddr_iomem; /* TODO: Use mapping abstraction properly */
-	sig = dst + AST_HWC_SIZE; /* TODO: Use mapping abstraction properly */
 
 	/*
-	 * Do data transfer to HW cursor BO. If a new cursor image was installed,
-	 * point the scanout engine to dst_gbo's offset and page-flip the HWC buffers.
+	 * Do data transfer to hardware buffer and point the scanout
+	 * engine to the offset.
 	 */
 
-	ast_update_cursor_image(dst, src, fb->width, fb->height);
-
-	if (fb != old_fb)
+	if (drm_atomic_helper_damage_merged(old_plane_state, plane_state, &damage)) {
+		ast_update_cursor_image(dst, src, fb->width, fb->height);
 		ast_set_cursor_base(ast, dst_off);
+	}
 
 	/*
 	 * Update location in HWC signature and registers.
@@ -900,36 +935,22 @@ static const struct drm_plane_helper_funcs ast_cursor_plane_helper_funcs = {
 	.atomic_disable = ast_cursor_plane_helper_atomic_disable,
 };
 
-static void ast_cursor_plane_destroy(struct drm_plane *plane)
-{
-	struct ast_plane *ast_plane = to_ast_plane(plane);
-	struct drm_gem_vram_object *gbo = ast_plane->gbo;
-	struct iosys_map map = ast_plane->map;
-
-	drm_gem_vram_vunmap(gbo, &map);
-	drm_gem_vram_unpin(gbo);
-	drm_gem_vram_put(gbo);
-
-	drm_plane_cleanup(plane);
-}
-
 static const struct drm_plane_funcs ast_cursor_plane_funcs = {
 	.update_plane = drm_atomic_helper_update_plane,
 	.disable_plane = drm_atomic_helper_disable_plane,
-	.destroy = ast_cursor_plane_destroy,
+	.destroy = drm_plane_cleanup,
 	DRM_GEM_SHADOW_PLANE_FUNCS,
 };
 
 static int ast_cursor_plane_init(struct ast_private *ast)
 {
 	struct drm_device *dev = &ast->base;
-	struct ast_plane *ast_plane = &ast->cursor_plane;
-	struct drm_plane *cursor_plane = &ast_plane->base;
+	struct ast_plane *ast_cursor_plane = &ast->cursor_plane;
+	struct drm_plane *cursor_plane = &ast_cursor_plane->base;
 	size_t size;
-	struct drm_gem_vram_object *gbo;
-	struct iosys_map map;
+	void __iomem *vaddr;
+	u64 offset;
 	int ret;
-	s64 off;
 
 	/*
 	 * Allocate backing storage for cursors. The BOs are permanently
@@ -938,52 +959,26 @@ static int ast_cursor_plane_init(struct ast_private *ast)
 
 	size = roundup(AST_HWC_SIZE + AST_HWC_SIGNATURE_SIZE, PAGE_SIZE);
 
-	gbo = drm_gem_vram_create(dev, size, 0);
-	if (IS_ERR(gbo))
-		return PTR_ERR(gbo);
-
-	ret = drm_gem_vram_pin(gbo, DRM_GEM_VRAM_PL_FLAG_VRAM |
-				    DRM_GEM_VRAM_PL_FLAG_TOPDOWN);
-	if (ret)
-		goto err_drm_gem_vram_put;
-	ret = drm_gem_vram_vmap(gbo, &map);
-	if (ret)
-		goto err_drm_gem_vram_unpin;
-	off = drm_gem_vram_offset(gbo);
-	if (off < 0) {
-		ret = off;
-		goto err_drm_gem_vram_vunmap;
-	}
+	if (ast->vram_fb_available < size)
+		return -ENOMEM;
 
-	ast_plane->gbo = gbo;
-	ast_plane->map = map;
-	ast_plane->off = off;
-
-	/*
-	 * Create the cursor plane. The plane's destroy callback will release
-	 * the backing storages' BO memory.
-	 */
+	vaddr = ast->vram + ast->vram_fb_available - size;
+	offset = ast->vram_base + ast->vram_fb_available - size;
 
-	ret = drm_universal_plane_init(dev, cursor_plane, 0x01,
-				       &ast_cursor_plane_funcs,
-				       ast_cursor_plane_formats,
-				       ARRAY_SIZE(ast_cursor_plane_formats),
-				       NULL, DRM_PLANE_TYPE_CURSOR, NULL);
+	ret = ast_plane_init(dev, ast_cursor_plane, vaddr, offset, size,
+			     0x01, &ast_cursor_plane_funcs,
+			     ast_cursor_plane_formats, ARRAY_SIZE(ast_cursor_plane_formats),
+			     NULL, DRM_PLANE_TYPE_CURSOR);
 	if (ret) {
-		drm_err(dev, "drm_universal_plane failed(): %d\n", ret);
-		goto err_drm_gem_vram_vunmap;
+		drm_err(dev, "ast_plane_init() failed: %d\n", ret);
+		return ret;
 	}
 	drm_plane_helper_add(cursor_plane, &ast_cursor_plane_helper_funcs);
+	drm_plane_enable_fb_damage_clips(cursor_plane);
 
-	return 0;
+	ast->vram_fb_available -= size;
 
-err_drm_gem_vram_vunmap:
-	drm_gem_vram_vunmap(gbo, &map);
-err_drm_gem_vram_unpin:
-	drm_gem_vram_unpin(gbo);
-err_drm_gem_vram_put:
-	drm_gem_vram_put(gbo);
-	return ret;
+	return 0;
 }
 
 /*
@@ -1313,7 +1308,7 @@ static int ast_crtc_init(struct drm_device *dev)
 	struct drm_crtc *crtc = &ast->crtc;
 	int ret;
 
-	ret = drm_crtc_init_with_planes(dev, crtc, &ast->primary_plane,
+	ret = drm_crtc_init_with_planes(dev, crtc, &ast->primary_plane.base,
 					&ast->cursor_plane.base, &ast_crtc_funcs,
 					NULL);
 	if (ret)
@@ -1735,9 +1730,27 @@ static const struct drm_mode_config_helper_funcs ast_mode_config_helper_funcs =
 	.atomic_commit_tail = ast_mode_config_helper_atomic_commit_tail,
 };
 
+static enum drm_mode_status ast_mode_config_mode_valid(struct drm_device *dev,
+						       const struct drm_display_mode *mode)
+{
+	static const unsigned long max_bpp = 4; /* DRM_FORMAT_XRGB8888 */
+	struct ast_private *ast = to_ast_private(dev);
+	unsigned long fbsize, fbpages, max_fbpages;
+
+	max_fbpages = (ast->vram_fb_available) >> PAGE_SHIFT;
+
+	fbsize = mode->hdisplay * mode->vdisplay * max_bpp;
+	fbpages = DIV_ROUND_UP(fbsize, PAGE_SIZE);
+
+	if (fbpages > max_fbpages)
+		return MODE_MEM;
+
+	return MODE_OK;
+}
+
 static const struct drm_mode_config_funcs ast_mode_config_funcs = {
-	.fb_create = drm_gem_fb_create,
-	.mode_valid = drm_vram_helper_mode_valid,
+	.fb_create = drm_gem_fb_create_with_dirty,
+	.mode_valid = ast_mode_config_mode_valid,
 	.atomic_check = drm_atomic_helper_check,
 	.atomic_commit = drm_atomic_helper_commit,
 };
@@ -1756,7 +1769,6 @@ int ast_mode_config_init(struct ast_private *ast)
 	dev->mode_config.min_width = 0;
 	dev->mode_config.min_height = 0;
 	dev->mode_config.preferred_depth = 24;
-	dev->mode_config.prefer_shadow = 1;
 	dev->mode_config.fb_base = pci_resource_start(pdev, 0);
 
 	if (ast->chip == AST2100 ||