Linux kernel mirror (for testing)
git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
kernel
os
linux
drm/tegra: gem: Don't attach dma-bufs when not needed
The dma-buf import code currently attaches and maps all imported
dma-bufs to the drm device to get their sgt for mapping to the
directly managed IOMMU domain.
In many cases, like for newer chips (Tegra186+), the directly
managed IOMMU domain is, however, not used. Mapping to the drm
device can also cause issues e.g. with swiotlb since it is not
a real device.
To improve the situation, only attach and map imported dma-bufs
when required.
Signed-off-by: Mikko Perttunen <mperttunen@nvidia.com>
Signed-off-by: Thierry Reding <treding@nvidia.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20240424051335.2872574-2-cyndis@kapsi.fi
authored by
Mikko Perttunen
and committed by
Thierry Reding
f5b8794e
4ed09565
+58
-31
+37
-31
drivers/gpu/drm/tegra/gem.c
+37
-31
drivers/gpu/drm/tegra/gem.c
···
76
76
/*
77
77
* Imported buffers need special treatment to satisfy the semantics of DMA-BUF.
78
78
*/
79
-
if (gem->import_attach) {
80
-
struct dma_buf *buf = gem->import_attach->dmabuf;
79
+
if (obj->dma_buf) {
80
+
struct dma_buf *buf = obj->dma_buf;
81
81
82
82
map->attach = dma_buf_attach(buf, dev);
83
83
if (IS_ERR(map->attach)) {
···
184
184
if (obj->vaddr)
185
185
return obj->vaddr;
186
186
187
-
if (obj->gem.import_attach) {
188
-
ret = dma_buf_vmap_unlocked(obj->gem.import_attach->dmabuf, &map);
187
+
if (obj->dma_buf) {
188
+
ret = dma_buf_vmap_unlocked(obj->dma_buf, &map);
189
189
if (ret < 0)
190
190
return ERR_PTR(ret);
191
191
···
208
208
if (obj->vaddr)
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return;
210
210
211
-
if (obj->gem.import_attach)
212
-
return dma_buf_vunmap_unlocked(obj->gem.import_attach->dmabuf, &map);
211
+
if (obj->dma_buf)
212
+
return dma_buf_vunmap_unlocked(obj->dma_buf, &map);
213
213
214
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vunmap(addr);
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215
}
···
465
465
if (IS_ERR(bo))
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return bo;
467
467
468
-
attach = dma_buf_attach(buf, drm->dev);
469
-
if (IS_ERR(attach)) {
470
-
err = PTR_ERR(attach);
471
-
goto free;
472
-
}
473
-
474
-
get_dma_buf(buf);
475
-
476
-
bo->sgt = dma_buf_map_attachment_unlocked(attach, DMA_TO_DEVICE);
477
-
if (IS_ERR(bo->sgt)) {
478
-
err = PTR_ERR(bo->sgt);
479
-
goto detach;
480
-
}
481
-
468
+
/*
469
+
* If we need to use IOMMU API to map the dma-buf into the internally managed
470
+
* domain, map it first to the DRM device to get an sgt.
471
+
*/
482
472
if (tegra->domain) {
473
+
attach = dma_buf_attach(buf, drm->dev);
474
+
if (IS_ERR(attach)) {
475
+
err = PTR_ERR(attach);
476
+
goto free;
477
+
}
478
+
479
+
bo->sgt = dma_buf_map_attachment_unlocked(attach, DMA_TO_DEVICE);
480
+
if (IS_ERR(bo->sgt)) {
481
+
err = PTR_ERR(bo->sgt);
482
+
goto detach;
483
+
}
484
+
483
485
err = tegra_bo_iommu_map(tegra, bo);
484
486
if (err < 0)
485
487
goto detach;
488
+
489
+
bo->gem.import_attach = attach;
486
490
}
487
491
488
-
bo->gem.import_attach = attach;
492
+
get_dma_buf(buf);
493
+
bo->dma_buf = buf;
489
494
490
495
return bo;
491
496
···
521
516
dev_name(mapping->dev));
522
517
}
523
518
524
-
if (tegra->domain)
519
+
if (tegra->domain) {
525
520
tegra_bo_iommu_unmap(tegra, bo);
526
521
527
-
if (gem->import_attach) {
528
-
struct dma_buf *dmabuf = gem->import_attach->dmabuf;
529
-
530
-
dma_buf_unmap_attachment_unlocked(gem->import_attach, bo->sgt,
531
-
DMA_TO_DEVICE);
532
-
dma_buf_detach(dmabuf, gem->import_attach);
533
-
dma_buf_put(dmabuf);
534
-
} else {
535
-
tegra_bo_free(gem->dev, bo);
522
+
if (gem->import_attach) {
523
+
dma_buf_unmap_attachment_unlocked(gem->import_attach, bo->sgt,
524
+
DMA_TO_DEVICE);
525
+
dma_buf_detach(gem->import_attach->dmabuf, gem->import_attach);
526
+
}
536
527
}
528
+
529
+
tegra_bo_free(gem->dev, bo);
530
+
531
+
if (bo->dma_buf)
532
+
dma_buf_put(bo->dma_buf);
537
533
538
534
drm_gem_object_release(gem);
539
535
kfree(bo);
+21
drivers/gpu/drm/tegra/gem.h
+21
drivers/gpu/drm/tegra/gem.h
···
32
32
enum tegra_bo_sector_layout sector_layout;
33
33
};
34
34
35
+
/*
36
+
* How memory is referenced within a tegra_bo:
37
+
*
38
+
* Buffer source | Mapping API(*) | Fields
39
+
* ---------------+-----------------+---------------
40
+
* Allocated here | DMA API | iova (IOVA mapped to drm->dev), vaddr (CPU VA)
41
+
*
42
+
* Allocated here | IOMMU API | pages/num_pages (Phys. memory), sgt (Mapped to drm->dev),
43
+
* | iova/size (Mapped to domain)
44
+
*
45
+
* Imported | DMA API | dma_buf (Imported dma_buf)
46
+
*
47
+
* Imported | IOMMU API | dma_buf (Imported dma_buf),
48
+
* | gem->import_attach (Attachment on drm->dev),
49
+
* | sgt (Mapped to drm->dev)
50
+
* | iova/size (Mapped to domain)
51
+
*
52
+
* (*) If tegra->domain is set, i.e. TegraDRM IOMMU domain is directly managed through IOMMU API,
53
+
* this is IOMMU API. Otherwise DMA API.
54
+
*/
35
55
struct tegra_bo {
36
56
struct drm_gem_object gem;
37
57
struct host1x_bo base;
···
59
39
struct sg_table *sgt;
60
40
dma_addr_t iova;
61
41
void *vaddr;
42
+
struct dma_buf *dma_buf;
62
43
63
44
struct drm_mm_node *mm;
64
45
unsigned long num_pages;