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_fb_helper.h>
20 #include <drm/drm_fourcc.h>
21 #include <drm/drm_framebuffer.h>
22 #include <drm/drm_gem.h>
23 #include <drm/drm_gem_framebuffer_helper.h>
24 #include <drm/drm_modeset_helper.h>
25 #include <drm/drm_simple_kms_helper.h>
30 * This library provides helpers for drivers that don't subclass
31 * &drm_framebuffer and use &drm_gem_object for their backing storage.
33 * Drivers without additional needs to validate framebuffers can simply use
34 * drm_gem_fb_create() and everything is wired up automatically. Other drivers
35 * can use all parts independently.
39 * drm_gem_fb_get_obj() - Get GEM object backing the framebuffer
43 * No additional reference is taken beyond the one that the &drm_frambuffer
47 * Pointer to &drm_gem_object for the given framebuffer and plane index or NULL
48 * if it does not exist.
50 struct drm_gem_object
*drm_gem_fb_get_obj(struct drm_framebuffer
*fb
,
56 return fb
->obj
[plane
];
58 EXPORT_SYMBOL_GPL(drm_gem_fb_get_obj
);
60 static struct drm_framebuffer
*
61 drm_gem_fb_alloc(struct drm_device
*dev
,
62 const struct drm_mode_fb_cmd2
*mode_cmd
,
63 struct drm_gem_object
**obj
, unsigned int num_planes
,
64 const struct drm_framebuffer_funcs
*funcs
)
66 struct drm_framebuffer
*fb
;
69 fb
= kzalloc(sizeof(*fb
), GFP_KERNEL
);
71 return ERR_PTR(-ENOMEM
);
73 drm_helper_mode_fill_fb_struct(dev
, fb
, mode_cmd
);
75 for (i
= 0; i
< num_planes
; i
++)
78 ret
= drm_framebuffer_init(dev
, fb
, funcs
);
80 DRM_DEV_ERROR(dev
->dev
, "Failed to init framebuffer: %d\n",
90 * drm_gem_fb_destroy - Free GEM backed framebuffer
93 * Frees a GEM backed framebuffer with its backing buffer(s) and the structure
94 * itself. Drivers can use this as their &drm_framebuffer_funcs->destroy
97 void drm_gem_fb_destroy(struct drm_framebuffer
*fb
)
101 for (i
= 0; i
< 4; i
++)
102 drm_gem_object_put_unlocked(fb
->obj
[i
]);
104 drm_framebuffer_cleanup(fb
);
107 EXPORT_SYMBOL(drm_gem_fb_destroy
);
110 * drm_gem_fb_create_handle - Create handle for GEM backed framebuffer
112 * @file: DRM file to register the handle for
113 * @handle: Pointer to return the created handle
115 * This function creates a handle for the GEM object backing the framebuffer.
116 * Drivers can use this as their &drm_framebuffer_funcs->create_handle
117 * callback. The GETFB IOCTL calls into this callback.
120 * 0 on success or a negative error code on failure.
122 int drm_gem_fb_create_handle(struct drm_framebuffer
*fb
, struct drm_file
*file
,
123 unsigned int *handle
)
125 return drm_gem_handle_create(file
, fb
->obj
[0], handle
);
127 EXPORT_SYMBOL(drm_gem_fb_create_handle
);
130 * drm_gem_fb_create_with_funcs() - Helper function for the
131 * &drm_mode_config_funcs.fb_create
134 * @file: DRM file that holds the GEM handle(s) backing the framebuffer
135 * @mode_cmd: Metadata from the userspace framebuffer creation request
136 * @funcs: vtable to be used for the new framebuffer object
138 * This can be used to set &drm_framebuffer_funcs for drivers that need the
139 * &drm_framebuffer_funcs.dirty callback. Use drm_gem_fb_create() if you don't
140 * need to change &drm_framebuffer_funcs.
141 * The function does buffer size validation.
144 * Pointer to a &drm_framebuffer on success or an error pointer on failure.
146 struct drm_framebuffer
*
147 drm_gem_fb_create_with_funcs(struct drm_device
*dev
, struct drm_file
*file
,
148 const struct drm_mode_fb_cmd2
*mode_cmd
,
149 const struct drm_framebuffer_funcs
*funcs
)
151 const struct drm_format_info
*info
;
152 struct drm_gem_object
*objs
[4];
153 struct drm_framebuffer
*fb
;
156 info
= drm_get_format_info(dev
, mode_cmd
);
158 return ERR_PTR(-EINVAL
);
160 for (i
= 0; i
< info
->num_planes
; i
++) {
161 unsigned int width
= mode_cmd
->width
/ (i
? info
->hsub
: 1);
162 unsigned int height
= mode_cmd
->height
/ (i
? info
->vsub
: 1);
163 unsigned int min_size
;
165 objs
[i
] = drm_gem_object_lookup(file
, mode_cmd
->handles
[i
]);
167 DRM_DEBUG_KMS("Failed to lookup GEM object\n");
169 goto err_gem_object_put
;
172 min_size
= (height
- 1) * mode_cmd
->pitches
[i
]
173 + width
* info
->cpp
[i
]
174 + mode_cmd
->offsets
[i
];
176 if (objs
[i
]->size
< min_size
) {
177 drm_gem_object_put_unlocked(objs
[i
]);
179 goto err_gem_object_put
;
183 fb
= drm_gem_fb_alloc(dev
, mode_cmd
, objs
, i
, funcs
);
186 goto err_gem_object_put
;
192 for (i
--; i
>= 0; i
--)
193 drm_gem_object_put_unlocked(objs
[i
]);
197 EXPORT_SYMBOL_GPL(drm_gem_fb_create_with_funcs
);
199 static const struct drm_framebuffer_funcs drm_gem_fb_funcs
= {
200 .destroy
= drm_gem_fb_destroy
,
201 .create_handle
= drm_gem_fb_create_handle
,
205 * drm_gem_fb_create() - Helper function for the
206 * &drm_mode_config_funcs.fb_create callback
208 * @file: DRM file that holds the GEM handle(s) backing the framebuffer
209 * @mode_cmd: Metadata from the userspace framebuffer creation request
211 * This function creates a new framebuffer object described by
212 * &drm_mode_fb_cmd2. This description includes handles for the buffer(s)
213 * backing the framebuffer.
215 * If your hardware has special alignment or pitch requirements these should be
216 * checked before calling this function. The function does buffer size
217 * validation. Use drm_gem_fb_create_with_funcs() if you need to set
218 * &drm_framebuffer_funcs.dirty.
220 * Drivers can use this as their &drm_mode_config_funcs.fb_create callback.
221 * The ADDFB2 IOCTL calls into this callback.
224 * Pointer to a &drm_framebuffer on success or an error pointer on failure.
226 struct drm_framebuffer
*
227 drm_gem_fb_create(struct drm_device
*dev
, struct drm_file
*file
,
228 const struct drm_mode_fb_cmd2
*mode_cmd
)
230 return drm_gem_fb_create_with_funcs(dev
, file
, mode_cmd
,
233 EXPORT_SYMBOL_GPL(drm_gem_fb_create
);
236 * drm_gem_fb_prepare_fb() - Prepare a GEM backed framebuffer
238 * @state: Plane state the fence will be attached to
240 * This function prepares a GEM backed framebuffer for scanout by checking if
241 * the plane framebuffer has a DMA-BUF attached. If it does, it extracts the
242 * exclusive fence and attaches it to the plane state for the atomic helper to
243 * wait on. This function can be used as the &drm_plane_helper_funcs.prepare_fb
246 * There is no need for &drm_plane_helper_funcs.cleanup_fb hook for simple
247 * gem based framebuffer drivers which have their buffers always pinned in
250 int drm_gem_fb_prepare_fb(struct drm_plane
*plane
,
251 struct drm_plane_state
*state
)
253 struct dma_buf
*dma_buf
;
254 struct dma_fence
*fence
;
259 dma_buf
= drm_gem_fb_get_obj(state
->fb
, 0)->dma_buf
;
261 fence
= reservation_object_get_excl_rcu(dma_buf
->resv
);
262 drm_atomic_set_fence_for_plane(state
, fence
);
267 EXPORT_SYMBOL_GPL(drm_gem_fb_prepare_fb
);
270 * drm_gem_fb_simple_display_pipe_prepare_fb - prepare_fb helper for
271 * &drm_simple_display_pipe
272 * @pipe: Simple display pipe
273 * @plane_state: Plane state
275 * This function uses drm_gem_fb_prepare_fb() to check if the plane FB has a
276 * &dma_buf attached, extracts the exclusive fence and attaches it to plane
277 * state for the atomic helper to wait on. Drivers can use this as their
278 * &drm_simple_display_pipe_funcs.prepare_fb callback.
280 int drm_gem_fb_simple_display_pipe_prepare_fb(struct drm_simple_display_pipe
*pipe
,
281 struct drm_plane_state
*plane_state
)
283 return drm_gem_fb_prepare_fb(&pipe
->plane
, plane_state
);
285 EXPORT_SYMBOL(drm_gem_fb_simple_display_pipe_prepare_fb
);
288 * drm_gem_fbdev_fb_create - Create a GEM backed &drm_framebuffer for fbdev
291 * @sizes: fbdev size description
292 * @pitch_align: Optional pitch alignment
293 * @obj: GEM object backing the framebuffer
294 * @funcs: Optional vtable to be used for the new framebuffer object when the
295 * dirty callback is needed.
297 * This function creates a framebuffer from a &drm_fb_helper_surface_size
298 * description for use in the &drm_fb_helper_funcs.fb_probe callback.
301 * Pointer to a &drm_framebuffer on success or an error pointer on failure.
303 struct drm_framebuffer
*
304 drm_gem_fbdev_fb_create(struct drm_device
*dev
,
305 struct drm_fb_helper_surface_size
*sizes
,
306 unsigned int pitch_align
, struct drm_gem_object
*obj
,
307 const struct drm_framebuffer_funcs
*funcs
)
309 struct drm_mode_fb_cmd2 mode_cmd
= { 0 };
311 mode_cmd
.width
= sizes
->surface_width
;
312 mode_cmd
.height
= sizes
->surface_height
;
313 mode_cmd
.pitches
[0] = sizes
->surface_width
*
314 DIV_ROUND_UP(sizes
->surface_bpp
, 8);
316 mode_cmd
.pitches
[0] = roundup(mode_cmd
.pitches
[0],
318 mode_cmd
.pixel_format
= drm_mode_legacy_fb_format(sizes
->surface_bpp
,
319 sizes
->surface_depth
);
320 if (obj
->size
< mode_cmd
.pitches
[0] * mode_cmd
.height
)
321 return ERR_PTR(-EINVAL
);
324 funcs
= &drm_gem_fb_funcs
;
326 return drm_gem_fb_alloc(dev
, &mode_cmd
, &obj
, 1, funcs
);
328 EXPORT_SYMBOL(drm_gem_fbdev_fb_create
);