Linux kernel mirror (for testing)
git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
kernel
os
linux
drm/panfrost: Provide a custom dma_buf implementation
Before we introduce cached CPU mappings, we want a dma_buf
implementation satisfying synchronization requests around CPU
accesses coming from a dma_buf exported by our driver. Let's
provide our own implementation relying on the default
gem_shmem_prime helpers designed for that purpose.
v5:
- New patch
v6:
- Collect R-b
v7:
- Hand-roll our own dma_buf boilerplate
v8:
- No changes
Reviewed-by: Steven Price <steven.price@arm.com>
Link: https://patch.msgid.link/20251208100841.730527-9-boris.brezillon@collabora.com
Signed-off-by: Boris Brezillon <boris.brezillon@collabora.com>
+127
+1
drivers/gpu/drm/panfrost/panfrost_drv.c
+1
drivers/gpu/drm/panfrost/panfrost_drv.c
+123
drivers/gpu/drm/panfrost/panfrost_gem.c
+123
drivers/gpu/drm/panfrost/panfrost_gem.c
···
277
277
return 0;
278
278
}
279
279
280
+
static struct sg_table *
281
+
panfrost_gem_prime_map_dma_buf(struct dma_buf_attachment *attach,
282
+
enum dma_data_direction dir)
283
+
{
284
+
struct sg_table *sgt = drm_gem_map_dma_buf(attach, dir);
285
+
286
+
if (!IS_ERR(sgt))
287
+
attach->priv = sgt;
288
+
289
+
return sgt;
290
+
}
291
+
292
+
static void
293
+
panfrost_gem_prime_unmap_dma_buf(struct dma_buf_attachment *attach,
294
+
struct sg_table *sgt,
295
+
enum dma_data_direction dir)
296
+
{
297
+
attach->priv = NULL;
298
+
drm_gem_unmap_dma_buf(attach, sgt, dir);
299
+
}
300
+
301
+
static int
302
+
panfrost_gem_prime_begin_cpu_access(struct dma_buf *dma_buf,
303
+
enum dma_data_direction dir)
304
+
{
305
+
struct drm_gem_object *obj = dma_buf->priv;
306
+
struct drm_device *dev = obj->dev;
307
+
struct drm_gem_shmem_object *shmem = to_drm_gem_shmem_obj(obj);
308
+
struct dma_buf_attachment *attach;
309
+
310
+
dma_resv_lock(obj->resv, NULL);
311
+
if (shmem->sgt)
312
+
dma_sync_sgtable_for_cpu(dev->dev, shmem->sgt, dir);
313
+
314
+
if (shmem->vaddr)
315
+
invalidate_kernel_vmap_range(shmem->vaddr, shmem->base.size);
316
+
317
+
list_for_each_entry(attach, &dma_buf->attachments, node) {
318
+
struct sg_table *sgt = attach->priv;
319
+
320
+
if (sgt)
321
+
dma_sync_sgtable_for_cpu(attach->dev, sgt, dir);
322
+
}
323
+
dma_resv_unlock(obj->resv);
324
+
325
+
return 0;
326
+
}
327
+
328
+
static int
329
+
panfrost_gem_prime_end_cpu_access(struct dma_buf *dma_buf,
330
+
enum dma_data_direction dir)
331
+
{
332
+
struct drm_gem_object *obj = dma_buf->priv;
333
+
struct drm_device *dev = obj->dev;
334
+
struct drm_gem_shmem_object *shmem = to_drm_gem_shmem_obj(obj);
335
+
struct dma_buf_attachment *attach;
336
+
337
+
dma_resv_lock(obj->resv, NULL);
338
+
list_for_each_entry(attach, &dma_buf->attachments, node) {
339
+
struct sg_table *sgt = attach->priv;
340
+
341
+
if (sgt)
342
+
dma_sync_sgtable_for_device(attach->dev, sgt, dir);
343
+
}
344
+
345
+
if (shmem->vaddr)
346
+
flush_kernel_vmap_range(shmem->vaddr, shmem->base.size);
347
+
348
+
if (shmem->sgt)
349
+
dma_sync_sgtable_for_device(dev->dev, shmem->sgt, dir);
350
+
351
+
dma_resv_unlock(obj->resv);
352
+
return 0;
353
+
}
354
+
355
+
static const struct dma_buf_ops panfrost_dma_buf_ops = {
356
+
.attach = drm_gem_map_attach,
357
+
.detach = drm_gem_map_detach,
358
+
.map_dma_buf = panfrost_gem_prime_map_dma_buf,
359
+
.unmap_dma_buf = panfrost_gem_prime_unmap_dma_buf,
360
+
.release = drm_gem_dmabuf_release,
361
+
.mmap = drm_gem_dmabuf_mmap,
362
+
.vmap = drm_gem_dmabuf_vmap,
363
+
.vunmap = drm_gem_dmabuf_vunmap,
364
+
.begin_cpu_access = panfrost_gem_prime_begin_cpu_access,
365
+
.end_cpu_access = panfrost_gem_prime_end_cpu_access,
366
+
};
367
+
368
+
static struct dma_buf *
369
+
panfrost_gem_prime_export(struct drm_gem_object *obj, int flags)
370
+
{
371
+
struct drm_device *dev = obj->dev;
372
+
struct dma_buf_export_info exp_info = {
373
+
.exp_name = KBUILD_MODNAME,
374
+
.owner = THIS_MODULE,
375
+
.ops = &panfrost_dma_buf_ops,
376
+
.size = obj->size,
377
+
.flags = flags,
378
+
.priv = obj,
379
+
.resv = obj->resv,
380
+
};
381
+
382
+
return drm_gem_dmabuf_export(dev, &exp_info);
383
+
}
384
+
385
+
struct drm_gem_object *
386
+
panfrost_gem_prime_import(struct drm_device *dev,
387
+
struct dma_buf *dma_buf)
388
+
{
389
+
struct drm_gem_object *obj = dma_buf->priv;
390
+
391
+
if (dma_buf->ops == &panfrost_dma_buf_ops && obj->dev == dev) {
392
+
/* Importing dmabuf exported from our own gem increases
393
+
* refcount on gem itself instead of f_count of dmabuf.
394
+
*/
395
+
drm_gem_object_get(obj);
396
+
return obj;
397
+
}
398
+
399
+
return drm_gem_prime_import(dev, dma_buf);
400
+
}
401
+
280
402
static const struct drm_gem_object_funcs panfrost_gem_funcs = {
281
403
.free = panfrost_gem_free_object,
282
404
.open = panfrost_gem_open,
···
407
285
.pin = panfrost_gem_pin,
408
286
.unpin = drm_gem_shmem_object_unpin,
409
287
.get_sg_table = drm_gem_shmem_object_get_sg_table,
288
+
.export = panfrost_gem_prime_export,
410
289
.vmap = drm_gem_shmem_object_vmap,
411
290
.vunmap = drm_gem_shmem_object_vunmap,
412
291
.mmap = drm_gem_shmem_object_mmap,
+3
drivers/gpu/drm/panfrost/panfrost_gem.h
+3
drivers/gpu/drm/panfrost/panfrost_gem.h
···
132
132
panfrost_gem_prime_import_sg_table(struct drm_device *dev,
133
133
struct dma_buf_attachment *attach,
134
134
struct sg_table *sgt);
135
+
struct drm_gem_object *
136
+
panfrost_gem_prime_import(struct drm_device *dev,
137
+
struct dma_buf *dma_buf);
135
138
136
139
struct panfrost_gem_object *
137
140
panfrost_gem_create(struct drm_device *dev, size_t size, u32 flags);