2 * drm gem framebuffer helper functions
4 * Copyright (C) 2017 Noralf Trønnes
6 * This program is free software; you can redistribute it and/or modify
7 * it under the terms of the GNU General Public License as published by
8 * the Free Software Foundation; either version 2 of the License, or
9 * (at your option) any later version.
12 #include <linux/dma-buf.h>
13 #include <linux/dma-fence.h>
14 #include <linux/reservation.h>
15 #include <linux/slab.h>
18 #include <drm/drm_atomic.h>
19 #include <drm/drm_atomic_uapi.h>
20 #include <drm/drm_fb_helper.h>
21 #include <drm/drm_fourcc.h>
22 #include <drm/drm_framebuffer.h>
23 #include <drm/drm_gem.h>
24 #include <drm/drm_gem_framebuffer_helper.h>
25 #include <drm/drm_modeset_helper.h>
26 #include <drm/drm_simple_kms_helper.h>
31 * This library provides helpers for drivers that don't subclass
32 * &drm_framebuffer and use &drm_gem_object for their backing storage.
34 * Drivers without additional needs to validate framebuffers can simply use
35 * drm_gem_fb_create() and everything is wired up automatically. Other drivers
36 * can use all parts independently.
40 * drm_gem_fb_get_obj() - Get GEM object backing the framebuffer
44 * No additional reference is taken beyond the one that the &drm_frambuffer
48 * Pointer to &drm_gem_object for the given framebuffer and plane index or NULL
49 * if it does not exist.
51 struct drm_gem_object *drm_gem_fb_get_obj(struct drm_framebuffer *fb,
57 return fb->obj[plane];
59 EXPORT_SYMBOL_GPL(drm_gem_fb_get_obj);
61 static struct drm_framebuffer *
62 drm_gem_fb_alloc(struct drm_device *dev,
63 const struct drm_mode_fb_cmd2 *mode_cmd,
64 struct drm_gem_object **obj, unsigned int num_planes,
65 const struct drm_framebuffer_funcs *funcs)
67 struct drm_framebuffer *fb;
70 fb = kzalloc(sizeof(*fb), GFP_KERNEL);
72 return ERR_PTR(-ENOMEM);
74 drm_helper_mode_fill_fb_struct(dev, fb, mode_cmd);
76 for (i = 0; i < num_planes; i++)
79 ret = drm_framebuffer_init(dev, fb, funcs);
81 DRM_DEV_ERROR(dev->dev, "Failed to init framebuffer: %d\n",
91 * drm_gem_fb_destroy - Free GEM backed framebuffer
94 * Frees a GEM backed framebuffer with its backing buffer(s) and the structure
95 * itself. Drivers can use this as their &drm_framebuffer_funcs->destroy
98 void drm_gem_fb_destroy(struct drm_framebuffer *fb)
102 for (i = 0; i < 4; i++)
103 drm_gem_object_put_unlocked(fb->obj[i]);
105 drm_framebuffer_cleanup(fb);
108 EXPORT_SYMBOL(drm_gem_fb_destroy);
111 * drm_gem_fb_create_handle - Create handle for GEM backed framebuffer
113 * @file: DRM file to register the handle for
114 * @handle: Pointer to return the created handle
116 * This function creates a handle for the GEM object backing the framebuffer.
117 * Drivers can use this as their &drm_framebuffer_funcs->create_handle
118 * callback. The GETFB IOCTL calls into this callback.
121 * 0 on success or a negative error code on failure.
123 int drm_gem_fb_create_handle(struct drm_framebuffer *fb, struct drm_file *file,
124 unsigned int *handle)
126 return drm_gem_handle_create(file, fb->obj[0], handle);
128 EXPORT_SYMBOL(drm_gem_fb_create_handle);
131 * drm_gem_fb_create_with_funcs() - Helper function for the
132 * &drm_mode_config_funcs.fb_create
135 * @file: DRM file that holds the GEM handle(s) backing the framebuffer
136 * @mode_cmd: Metadata from the userspace framebuffer creation request
137 * @funcs: vtable to be used for the new framebuffer object
139 * This can be used to set &drm_framebuffer_funcs for drivers that need the
140 * &drm_framebuffer_funcs.dirty callback. Use drm_gem_fb_create() if you don't
141 * need to change &drm_framebuffer_funcs.
142 * The function does buffer size validation.
145 * Pointer to a &drm_framebuffer on success or an error pointer on failure.
147 struct drm_framebuffer *
148 drm_gem_fb_create_with_funcs(struct drm_device *dev, struct drm_file *file,
149 const struct drm_mode_fb_cmd2 *mode_cmd,
150 const struct drm_framebuffer_funcs *funcs)
152 const struct drm_format_info *info;
153 struct drm_gem_object *objs[4];
154 struct drm_framebuffer *fb;
157 info = drm_get_format_info(dev, mode_cmd);
159 return ERR_PTR(-EINVAL);
161 for (i = 0; i < info->num_planes; i++) {
162 unsigned int width = mode_cmd->width / (i ? info->hsub : 1);
163 unsigned int height = mode_cmd->height / (i ? info->vsub : 1);
164 unsigned int min_size;
166 objs[i] = drm_gem_object_lookup(file, mode_cmd->handles[i]);
168 DRM_DEBUG_KMS("Failed to lookup GEM object\n");
170 goto err_gem_object_put;
173 min_size = (height - 1) * mode_cmd->pitches[i]
174 + drm_format_info_min_pitch(info, i, width)
175 + mode_cmd->offsets[i];
177 if (objs[i]->size < min_size) {
178 drm_gem_object_put_unlocked(objs[i]);
180 goto err_gem_object_put;
184 fb = drm_gem_fb_alloc(dev, mode_cmd, objs, i, funcs);
187 goto err_gem_object_put;
193 for (i--; i >= 0; i--)
194 drm_gem_object_put_unlocked(objs[i]);
198 EXPORT_SYMBOL_GPL(drm_gem_fb_create_with_funcs);
200 static const struct drm_framebuffer_funcs drm_gem_fb_funcs = {
201 .destroy = drm_gem_fb_destroy,
202 .create_handle = drm_gem_fb_create_handle,
206 * drm_gem_fb_create() - Helper function for the
207 * &drm_mode_config_funcs.fb_create callback
209 * @file: DRM file that holds the GEM handle(s) backing the framebuffer
210 * @mode_cmd: Metadata from the userspace framebuffer creation request
212 * This function creates a new framebuffer object described by
213 * &drm_mode_fb_cmd2. This description includes handles for the buffer(s)
214 * backing the framebuffer.
216 * If your hardware has special alignment or pitch requirements these should be
217 * checked before calling this function. The function does buffer size
218 * validation. Use drm_gem_fb_create_with_funcs() if you need to set
219 * &drm_framebuffer_funcs.dirty.
221 * Drivers can use this as their &drm_mode_config_funcs.fb_create callback.
222 * The ADDFB2 IOCTL calls into this callback.
225 * Pointer to a &drm_framebuffer on success or an error pointer on failure.
227 struct drm_framebuffer *
228 drm_gem_fb_create(struct drm_device *dev, struct drm_file *file,
229 const struct drm_mode_fb_cmd2 *mode_cmd)
231 return drm_gem_fb_create_with_funcs(dev, file, mode_cmd,
234 EXPORT_SYMBOL_GPL(drm_gem_fb_create);
237 * drm_gem_fb_prepare_fb() - Prepare a GEM backed framebuffer
239 * @state: Plane state the fence will be attached to
241 * This function prepares a GEM backed framebuffer for scanout by checking if
242 * the plane framebuffer has a DMA-BUF attached. If it does, it extracts the
243 * exclusive fence and attaches it to the plane state for the atomic helper to
244 * wait on. This function can be used as the &drm_plane_helper_funcs.prepare_fb
247 * There is no need for &drm_plane_helper_funcs.cleanup_fb hook for simple
248 * gem based framebuffer drivers which have their buffers always pinned in
251 int drm_gem_fb_prepare_fb(struct drm_plane *plane,
252 struct drm_plane_state *state)
254 struct dma_buf *dma_buf;
255 struct dma_fence *fence;
260 dma_buf = drm_gem_fb_get_obj(state->fb, 0)->dma_buf;
262 fence = reservation_object_get_excl_rcu(dma_buf->resv);
263 drm_atomic_set_fence_for_plane(state, fence);
268 EXPORT_SYMBOL_GPL(drm_gem_fb_prepare_fb);
271 * drm_gem_fb_simple_display_pipe_prepare_fb - prepare_fb helper for
272 * &drm_simple_display_pipe
273 * @pipe: Simple display pipe
274 * @plane_state: Plane state
276 * This function uses drm_gem_fb_prepare_fb() to check if the plane FB has a
277 * &dma_buf attached, extracts the exclusive fence and attaches it to plane
278 * state for the atomic helper to wait on. Drivers can use this as their
279 * &drm_simple_display_pipe_funcs.prepare_fb callback.
281 int drm_gem_fb_simple_display_pipe_prepare_fb(struct drm_simple_display_pipe *pipe,
282 struct drm_plane_state *plane_state)
284 return drm_gem_fb_prepare_fb(&pipe->plane, plane_state);
286 EXPORT_SYMBOL(drm_gem_fb_simple_display_pipe_prepare_fb);
289 * drm_gem_fbdev_fb_create - Create a GEM backed &drm_framebuffer for fbdev
292 * @sizes: fbdev size description
293 * @pitch_align: Optional pitch alignment
294 * @obj: GEM object backing the framebuffer
295 * @funcs: Optional vtable to be used for the new framebuffer object when the
296 * dirty callback is needed.
298 * This function creates a framebuffer from a &drm_fb_helper_surface_size
299 * description for use in the &drm_fb_helper_funcs.fb_probe callback.
302 * Pointer to a &drm_framebuffer on success or an error pointer on failure.
304 struct drm_framebuffer *
305 drm_gem_fbdev_fb_create(struct drm_device *dev,
306 struct drm_fb_helper_surface_size *sizes,
307 unsigned int pitch_align, struct drm_gem_object *obj,
308 const struct drm_framebuffer_funcs *funcs)
310 struct drm_mode_fb_cmd2 mode_cmd = { 0 };
312 mode_cmd.width = sizes->surface_width;
313 mode_cmd.height = sizes->surface_height;
314 mode_cmd.pitches[0] = sizes->surface_width *
315 DIV_ROUND_UP(sizes->surface_bpp, 8);
317 mode_cmd.pitches[0] = roundup(mode_cmd.pitches[0],
319 mode_cmd.pixel_format = drm_driver_legacy_fb_format(dev, sizes->surface_bpp,
320 sizes->surface_depth);
321 if (obj->size < mode_cmd.pitches[0] * mode_cmd.height)
322 return ERR_PTR(-EINVAL);
325 funcs = &drm_gem_fb_funcs;
327 return drm_gem_fb_alloc(dev, &mode_cmd, &obj, 1, funcs);
329 EXPORT_SYMBOL(drm_gem_fbdev_fb_create);