1 // SPDX-License-Identifier: GPL-2.0-or-later
3 * drm gem framebuffer helper functions
5 * Copyright (C) 2017 Noralf Trønnes
8 #include <linux/dma-buf.h>
9 #include <linux/dma-fence.h>
10 #include <linux/dma-resv.h>
11 #include <linux/slab.h>
13 #include <drm/drm_atomic.h>
14 #include <drm/drm_atomic_uapi.h>
15 #include <drm/drm_damage_helper.h>
16 #include <drm/drm_fb_helper.h>
17 #include <drm/drm_fourcc.h>
18 #include <drm/drm_framebuffer.h>
19 #include <drm/drm_gem.h>
20 #include <drm/drm_gem_framebuffer_helper.h>
21 #include <drm/drm_modeset_helper.h>
22 #include <drm/drm_simple_kms_helper.h>
27 * This library provides helpers for drivers that don't subclass
28 * &drm_framebuffer and use &drm_gem_object for their backing storage.
30 * Drivers without additional needs to validate framebuffers can simply use
31 * drm_gem_fb_create() and everything is wired up automatically. Other drivers
32 * can use all parts independently.
36 * drm_gem_fb_get_obj() - Get GEM object backing the framebuffer
40 * No additional reference is taken beyond the one that the &drm_frambuffer
44 * Pointer to &drm_gem_object for the given framebuffer and plane index or NULL
45 * if it does not exist.
47 struct drm_gem_object *drm_gem_fb_get_obj(struct drm_framebuffer *fb,
53 return fb->obj[plane];
55 EXPORT_SYMBOL_GPL(drm_gem_fb_get_obj);
57 static struct drm_framebuffer *
58 drm_gem_fb_alloc(struct drm_device *dev,
59 const struct drm_mode_fb_cmd2 *mode_cmd,
60 struct drm_gem_object **obj, unsigned int num_planes,
61 const struct drm_framebuffer_funcs *funcs)
63 struct drm_framebuffer *fb;
66 fb = kzalloc(sizeof(*fb), GFP_KERNEL);
68 return ERR_PTR(-ENOMEM);
70 drm_helper_mode_fill_fb_struct(dev, fb, mode_cmd);
72 for (i = 0; i < num_planes; i++)
75 ret = drm_framebuffer_init(dev, fb, funcs);
77 DRM_DEV_ERROR(dev->dev, "Failed to init framebuffer: %d\n",
87 * drm_gem_fb_destroy - Free GEM backed framebuffer
90 * Frees a GEM backed framebuffer with its backing buffer(s) and the structure
91 * itself. Drivers can use this as their &drm_framebuffer_funcs->destroy
94 void drm_gem_fb_destroy(struct drm_framebuffer *fb)
98 for (i = 0; i < 4; i++)
99 drm_gem_object_put_unlocked(fb->obj[i]);
101 drm_framebuffer_cleanup(fb);
104 EXPORT_SYMBOL(drm_gem_fb_destroy);
107 * drm_gem_fb_create_handle - Create handle for GEM backed framebuffer
109 * @file: DRM file to register the handle for
110 * @handle: Pointer to return the created handle
112 * This function creates a handle for the GEM object backing the framebuffer.
113 * Drivers can use this as their &drm_framebuffer_funcs->create_handle
114 * callback. The GETFB IOCTL calls into this callback.
117 * 0 on success or a negative error code on failure.
119 int drm_gem_fb_create_handle(struct drm_framebuffer *fb, struct drm_file *file,
120 unsigned int *handle)
122 return drm_gem_handle_create(file, fb->obj[0], handle);
124 EXPORT_SYMBOL(drm_gem_fb_create_handle);
127 * drm_gem_fb_create_with_funcs() - Helper function for the
128 * &drm_mode_config_funcs.fb_create
131 * @file: DRM file that holds the GEM handle(s) backing the framebuffer
132 * @mode_cmd: Metadata from the userspace framebuffer creation request
133 * @funcs: vtable to be used for the new framebuffer object
135 * This function can be used to set &drm_framebuffer_funcs for drivers that need
136 * custom framebuffer callbacks. Use drm_gem_fb_create() if you don't need to
137 * change &drm_framebuffer_funcs. The function does buffer size validation.
140 * Pointer to a &drm_framebuffer on success or an error pointer on failure.
142 struct drm_framebuffer *
143 drm_gem_fb_create_with_funcs(struct drm_device *dev, struct drm_file *file,
144 const struct drm_mode_fb_cmd2 *mode_cmd,
145 const struct drm_framebuffer_funcs *funcs)
147 const struct drm_format_info *info;
148 struct drm_gem_object *objs[4];
149 struct drm_framebuffer *fb;
152 info = drm_get_format_info(dev, mode_cmd);
154 return ERR_PTR(-EINVAL);
156 for (i = 0; i < info->num_planes; i++) {
157 unsigned int width = mode_cmd->width / (i ? info->hsub : 1);
158 unsigned int height = mode_cmd->height / (i ? info->vsub : 1);
159 unsigned int min_size;
161 objs[i] = drm_gem_object_lookup(file, mode_cmd->handles[i]);
163 DRM_DEBUG_KMS("Failed to lookup GEM object\n");
165 goto err_gem_object_put;
168 min_size = (height - 1) * mode_cmd->pitches[i]
169 + drm_format_info_min_pitch(info, i, width)
170 + mode_cmd->offsets[i];
172 if (objs[i]->size < min_size) {
173 drm_gem_object_put_unlocked(objs[i]);
175 goto err_gem_object_put;
179 fb = drm_gem_fb_alloc(dev, mode_cmd, objs, i, funcs);
182 goto err_gem_object_put;
188 for (i--; i >= 0; i--)
189 drm_gem_object_put_unlocked(objs[i]);
193 EXPORT_SYMBOL_GPL(drm_gem_fb_create_with_funcs);
195 static const struct drm_framebuffer_funcs drm_gem_fb_funcs = {
196 .destroy = drm_gem_fb_destroy,
197 .create_handle = drm_gem_fb_create_handle,
201 * drm_gem_fb_create() - Helper function for the
202 * &drm_mode_config_funcs.fb_create callback
204 * @file: DRM file that holds the GEM handle(s) backing the framebuffer
205 * @mode_cmd: Metadata from the userspace framebuffer creation request
207 * This function creates a new framebuffer object described by
208 * &drm_mode_fb_cmd2. This description includes handles for the buffer(s)
209 * backing the framebuffer.
211 * If your hardware has special alignment or pitch requirements these should be
212 * checked before calling this function. The function does buffer size
213 * validation. Use drm_gem_fb_create_with_dirty() if you need framebuffer
216 * Drivers can use this as their &drm_mode_config_funcs.fb_create callback.
217 * The ADDFB2 IOCTL calls into this callback.
220 * Pointer to a &drm_framebuffer on success or an error pointer on failure.
222 struct drm_framebuffer *
223 drm_gem_fb_create(struct drm_device *dev, struct drm_file *file,
224 const struct drm_mode_fb_cmd2 *mode_cmd)
226 return drm_gem_fb_create_with_funcs(dev, file, mode_cmd,
229 EXPORT_SYMBOL_GPL(drm_gem_fb_create);
231 static const struct drm_framebuffer_funcs drm_gem_fb_funcs_dirtyfb = {
232 .destroy = drm_gem_fb_destroy,
233 .create_handle = drm_gem_fb_create_handle,
234 .dirty = drm_atomic_helper_dirtyfb,
238 * drm_gem_fb_create_with_dirty() - Helper function for the
239 * &drm_mode_config_funcs.fb_create callback
241 * @file: DRM file that holds the GEM handle(s) backing the framebuffer
242 * @mode_cmd: Metadata from the userspace framebuffer creation request
244 * This function creates a new framebuffer object described by
245 * &drm_mode_fb_cmd2. This description includes handles for the buffer(s)
246 * backing the framebuffer. drm_atomic_helper_dirtyfb() is used for the dirty
247 * callback giving framebuffer flushing through the atomic machinery. Use
248 * drm_gem_fb_create() if you don't need the dirty callback.
249 * The function does buffer size validation.
251 * Drivers should also call drm_plane_enable_fb_damage_clips() on all planes
252 * to enable userspace to use damage clips also with the ATOMIC IOCTL.
254 * Drivers can use this as their &drm_mode_config_funcs.fb_create callback.
255 * The ADDFB2 IOCTL calls into this callback.
258 * Pointer to a &drm_framebuffer on success or an error pointer on failure.
260 struct drm_framebuffer *
261 drm_gem_fb_create_with_dirty(struct drm_device *dev, struct drm_file *file,
262 const struct drm_mode_fb_cmd2 *mode_cmd)
264 return drm_gem_fb_create_with_funcs(dev, file, mode_cmd,
265 &drm_gem_fb_funcs_dirtyfb);
267 EXPORT_SYMBOL_GPL(drm_gem_fb_create_with_dirty);
270 * drm_gem_fb_prepare_fb() - Prepare a GEM backed framebuffer
272 * @state: Plane state the fence will be attached to
274 * This function extracts the exclusive fence from &drm_gem_object.resv and
275 * attaches it to plane state for the atomic helper to wait on. This is
276 * necessary to correctly implement implicit synchronization for any buffers
277 * shared as a struct &dma_buf. This function can be used as the
278 * &drm_plane_helper_funcs.prepare_fb callback.
280 * There is no need for &drm_plane_helper_funcs.cleanup_fb hook for simple
281 * gem based framebuffer drivers which have their buffers always pinned in
284 * See drm_atomic_set_fence_for_plane() for a discussion of implicit and
285 * explicit fencing in atomic modeset updates.
287 int drm_gem_fb_prepare_fb(struct drm_plane *plane,
288 struct drm_plane_state *state)
290 struct drm_gem_object *obj;
291 struct dma_fence *fence;
296 obj = drm_gem_fb_get_obj(state->fb, 0);
297 fence = dma_resv_get_excl_rcu(obj->resv);
298 drm_atomic_set_fence_for_plane(state, fence);
302 EXPORT_SYMBOL_GPL(drm_gem_fb_prepare_fb);
305 * drm_gem_fb_simple_display_pipe_prepare_fb - prepare_fb helper for
306 * &drm_simple_display_pipe
307 * @pipe: Simple display pipe
308 * @plane_state: Plane state
310 * This function uses drm_gem_fb_prepare_fb() to extract the exclusive fence
311 * from &drm_gem_object.resv and attaches it to plane state for the atomic
312 * helper to wait on. This is necessary to correctly implement implicit
313 * synchronization for any buffers shared as a struct &dma_buf. Drivers can use
314 * this as their &drm_simple_display_pipe_funcs.prepare_fb callback.
316 * See drm_atomic_set_fence_for_plane() for a discussion of implicit and
317 * explicit fencing in atomic modeset updates.
319 int drm_gem_fb_simple_display_pipe_prepare_fb(struct drm_simple_display_pipe *pipe,
320 struct drm_plane_state *plane_state)
322 return drm_gem_fb_prepare_fb(&pipe->plane, plane_state);
324 EXPORT_SYMBOL(drm_gem_fb_simple_display_pipe_prepare_fb);