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_err(dev, "Failed to init framebuffer: %d\n", ret);
86 * drm_gem_fb_destroy - Free GEM backed framebuffer
89 * Frees a GEM backed framebuffer with its backing buffer(s) and the structure
90 * itself. Drivers can use this as their &drm_framebuffer_funcs->destroy
93 void drm_gem_fb_destroy(struct drm_framebuffer *fb)
97 for (i = 0; i < 4; i++)
98 drm_gem_object_put_unlocked(fb->obj[i]);
100 drm_framebuffer_cleanup(fb);
103 EXPORT_SYMBOL(drm_gem_fb_destroy);
106 * drm_gem_fb_create_handle - Create handle for GEM backed framebuffer
108 * @file: DRM file to register the handle for
109 * @handle: Pointer to return the created handle
111 * This function creates a handle for the GEM object backing the framebuffer.
112 * Drivers can use this as their &drm_framebuffer_funcs->create_handle
113 * callback. The GETFB IOCTL calls into this callback.
116 * 0 on success or a negative error code on failure.
118 int drm_gem_fb_create_handle(struct drm_framebuffer *fb, struct drm_file *file,
119 unsigned int *handle)
121 return drm_gem_handle_create(file, fb->obj[0], handle);
123 EXPORT_SYMBOL(drm_gem_fb_create_handle);
126 * drm_gem_fb_create_with_funcs() - Helper function for the
127 * &drm_mode_config_funcs.fb_create
130 * @file: DRM file that holds the GEM handle(s) backing the framebuffer
131 * @mode_cmd: Metadata from the userspace framebuffer creation request
132 * @funcs: vtable to be used for the new framebuffer object
134 * This function can be used to set &drm_framebuffer_funcs for drivers that need
135 * custom framebuffer callbacks. Use drm_gem_fb_create() if you don't need to
136 * change &drm_framebuffer_funcs. The function does buffer size validation.
139 * Pointer to a &drm_framebuffer on success or an error pointer on failure.
141 struct drm_framebuffer *
142 drm_gem_fb_create_with_funcs(struct drm_device *dev, struct drm_file *file,
143 const struct drm_mode_fb_cmd2 *mode_cmd,
144 const struct drm_framebuffer_funcs *funcs)
146 const struct drm_format_info *info;
147 struct drm_gem_object *objs[4];
148 struct drm_framebuffer *fb;
151 info = drm_get_format_info(dev, mode_cmd);
153 return ERR_PTR(-EINVAL);
155 for (i = 0; i < info->num_planes; i++) {
156 unsigned int width = mode_cmd->width / (i ? info->hsub : 1);
157 unsigned int height = mode_cmd->height / (i ? info->vsub : 1);
158 unsigned int min_size;
160 objs[i] = drm_gem_object_lookup(file, mode_cmd->handles[i]);
162 drm_dbg_kms(dev, "Failed to lookup GEM object\n");
164 goto err_gem_object_put;
167 min_size = (height - 1) * mode_cmd->pitches[i]
168 + drm_format_info_min_pitch(info, i, width)
169 + mode_cmd->offsets[i];
171 if (objs[i]->size < min_size) {
172 drm_gem_object_put_unlocked(objs[i]);
174 goto err_gem_object_put;
178 fb = drm_gem_fb_alloc(dev, mode_cmd, objs, i, funcs);
181 goto err_gem_object_put;
187 for (i--; i >= 0; i--)
188 drm_gem_object_put_unlocked(objs[i]);
192 EXPORT_SYMBOL_GPL(drm_gem_fb_create_with_funcs);
194 static const struct drm_framebuffer_funcs drm_gem_fb_funcs = {
195 .destroy = drm_gem_fb_destroy,
196 .create_handle = drm_gem_fb_create_handle,
200 * drm_gem_fb_create() - Helper function for the
201 * &drm_mode_config_funcs.fb_create callback
203 * @file: DRM file that holds the GEM handle(s) backing the framebuffer
204 * @mode_cmd: Metadata from the userspace framebuffer creation request
206 * This function creates a new framebuffer object described by
207 * &drm_mode_fb_cmd2. This description includes handles for the buffer(s)
208 * backing the framebuffer.
210 * If your hardware has special alignment or pitch requirements these should be
211 * checked before calling this function. The function does buffer size
212 * validation. Use drm_gem_fb_create_with_dirty() if you need framebuffer
215 * Drivers can use this as their &drm_mode_config_funcs.fb_create callback.
216 * The ADDFB2 IOCTL calls into this callback.
219 * Pointer to a &drm_framebuffer on success or an error pointer on failure.
221 struct drm_framebuffer *
222 drm_gem_fb_create(struct drm_device *dev, struct drm_file *file,
223 const struct drm_mode_fb_cmd2 *mode_cmd)
225 return drm_gem_fb_create_with_funcs(dev, file, mode_cmd,
228 EXPORT_SYMBOL_GPL(drm_gem_fb_create);
230 static const struct drm_framebuffer_funcs drm_gem_fb_funcs_dirtyfb = {
231 .destroy = drm_gem_fb_destroy,
232 .create_handle = drm_gem_fb_create_handle,
233 .dirty = drm_atomic_helper_dirtyfb,
237 * drm_gem_fb_create_with_dirty() - Helper function for the
238 * &drm_mode_config_funcs.fb_create callback
240 * @file: DRM file that holds the GEM handle(s) backing the framebuffer
241 * @mode_cmd: Metadata from the userspace framebuffer creation request
243 * This function creates a new framebuffer object described by
244 * &drm_mode_fb_cmd2. This description includes handles for the buffer(s)
245 * backing the framebuffer. drm_atomic_helper_dirtyfb() is used for the dirty
246 * callback giving framebuffer flushing through the atomic machinery. Use
247 * drm_gem_fb_create() if you don't need the dirty callback.
248 * The function does buffer size validation.
250 * Drivers should also call drm_plane_enable_fb_damage_clips() on all planes
251 * to enable userspace to use damage clips also with the ATOMIC IOCTL.
253 * Drivers can use this as their &drm_mode_config_funcs.fb_create callback.
254 * The ADDFB2 IOCTL calls into this callback.
257 * Pointer to a &drm_framebuffer on success or an error pointer on failure.
259 struct drm_framebuffer *
260 drm_gem_fb_create_with_dirty(struct drm_device *dev, struct drm_file *file,
261 const struct drm_mode_fb_cmd2 *mode_cmd)
263 return drm_gem_fb_create_with_funcs(dev, file, mode_cmd,
264 &drm_gem_fb_funcs_dirtyfb);
266 EXPORT_SYMBOL_GPL(drm_gem_fb_create_with_dirty);
269 * drm_gem_fb_prepare_fb() - Prepare a GEM backed framebuffer
271 * @state: Plane state the fence will be attached to
273 * This function extracts the exclusive fence from &drm_gem_object.resv and
274 * attaches it to plane state for the atomic helper to wait on. This is
275 * necessary to correctly implement implicit synchronization for any buffers
276 * shared as a struct &dma_buf. This function can be used as the
277 * &drm_plane_helper_funcs.prepare_fb callback.
279 * There is no need for &drm_plane_helper_funcs.cleanup_fb hook for simple
280 * gem based framebuffer drivers which have their buffers always pinned in
283 * See drm_atomic_set_fence_for_plane() for a discussion of implicit and
284 * explicit fencing in atomic modeset updates.
286 int drm_gem_fb_prepare_fb(struct drm_plane *plane,
287 struct drm_plane_state *state)
289 struct drm_gem_object *obj;
290 struct dma_fence *fence;
295 obj = drm_gem_fb_get_obj(state->fb, 0);
296 fence = dma_resv_get_excl_rcu(obj->resv);
297 drm_atomic_set_fence_for_plane(state, fence);
301 EXPORT_SYMBOL_GPL(drm_gem_fb_prepare_fb);
304 * drm_gem_fb_simple_display_pipe_prepare_fb - prepare_fb helper for
305 * &drm_simple_display_pipe
306 * @pipe: Simple display pipe
307 * @plane_state: Plane state
309 * This function uses drm_gem_fb_prepare_fb() to extract the exclusive fence
310 * from &drm_gem_object.resv and attaches it to plane state for the atomic
311 * helper to wait on. This is necessary to correctly implement implicit
312 * synchronization for any buffers shared as a struct &dma_buf. Drivers can use
313 * this as their &drm_simple_display_pipe_funcs.prepare_fb callback.
315 * See drm_atomic_set_fence_for_plane() for a discussion of implicit and
316 * explicit fencing in atomic modeset updates.
318 int drm_gem_fb_simple_display_pipe_prepare_fb(struct drm_simple_display_pipe *pipe,
319 struct drm_plane_state *plane_state)
321 return drm_gem_fb_prepare_fb(&pipe->plane, plane_state);
323 EXPORT_SYMBOL(drm_gem_fb_simple_display_pipe_prepare_fb);