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Drivers using DRM_GEM_SHADOW_PLANE_HELPER_FUNCS and > DRM_GEM_SHMEM_DRIVER_OPS (e.g., udl, ast) do not require > sg_table import. > They only need dma_buf_vmap() to access the shared buffer's > kernel virtual address. > > 2. On certain Aspeed-based boards, a dma_mask of 0xffff_ffff may > trigger SWIOTLB during dmabuf import. However, IO_TLB_SEGSIZE > restricts the maximum DMA streaming mapping memory, resulting in > errors like: > > ast 0000:07:00.0: swiotlb buffer is full (sz: 3145728 bytes), total 32768 (slots), used 0 (slots) > > [HOW] > Provide a gem_prime_import implementation without sg_table mapping > to avoid issues (e.g., "swiotlb buffer is full"). Drivers that do not > require sg_table can adopt this. > > Signed-off-by: Shixiong Ou > --- > v1->v2: > Patch rebase. > v2->v3: > Rename the import callback function. > Remove drm_gem_shmem_prime_export() and separate some codes > to drm_gem_prime_import_self(). > v3->v4: > Separate the test from the policy. > Rename the macro. > > drivers/gpu/drm/drm_gem_shmem_helper.c | 57 ++++++++++++++++++++++++++ > drivers/gpu/drm/drm_prime.c | 36 ++++++++++++---- > include/drm/drm_gem_shmem_helper.h | 15 +++++++ > include/drm/drm_prime.h | 3 ++ > 4 files changed, 102 insertions(+), 9 deletions(-) > > diff --git a/drivers/gpu/drm/drm_gem_shmem_helper.c b/drivers/gpu/drm/drm_gem_shmem_helper.c > index aa43265f4f4f..8fa160c3635e 100644 > --- a/drivers/gpu/drm/drm_gem_shmem_helper.c > +++ b/drivers/gpu/drm/drm_gem_shmem_helper.c > @@ -800,6 +800,63 @@ drm_gem_shmem_prime_import_sg_table(struct drm_device *dev, > } > EXPORT_SYMBOL_GPL(drm_gem_shmem_prime_import_sg_table); > > +/** > + * drm_gem_shmem_prime_import_no_sgt - Import dmabuf without mapping its sg_table > + * @dev: Device to import into > + * @dma_buf: dma-buf object to import > + * > + * Drivers that use the shmem helpers but also wants to import dmabuf without > + * mapping its sg_table can use this as their &drm_driver.gem_prime_import > + * implementation. > + */ > +struct drm_gem_object *drm_gem_shmem_prime_import_no_sgt(struct drm_device *dev, > + struct dma_buf *dma_buf) Please don't mention "no sgt" in the name, that we use sgtable is an implementation detail. Maybe use something like "no map" or similar. > +{ > + struct dma_buf_attachment *attach; > + struct drm_gem_shmem_object *shmem; > + struct drm_gem_object *obj; > + size_t size; > + int ret; > + > + if (drm_gem_prime_exported_dma_buf(dev, dma_buf)) { > + /* > + * Importing dmabuf exported from our own gem increases > + * refcount on gem itself instead of f_count of dmabuf. > + */ > + obj = dma_buf->priv; > + drm_gem_object_get(obj); > + return obj; > + } > + > + attach = dma_buf_attach(dma_buf, dev->dev); > + if (IS_ERR(attach)) > + return ERR_CAST(attach); > + > + get_dma_buf(dma_buf); > + > + size = PAGE_ALIGN(attach->dmabuf->size); > + > + shmem = __drm_gem_shmem_create(dev, size, true, NULL); > + if (IS_ERR(shmem)) { > + ret = PTR_ERR(shmem); > + goto fail_detach; > + } > + > + drm_dbg_prime(dev, "size = %zu\n", size); > + > + shmem->base.import_attach = attach; > + shmem->base.resv = dma_buf->resv; > + > + return &shmem->base; > + > +fail_detach: > + dma_buf_detach(dma_buf, attach); > + dma_buf_put(dma_buf); > + > + return ERR_PTR(ret); > +} > +EXPORT_SYMBOL_GPL(drm_gem_shmem_prime_import_no_sgt); > + > MODULE_DESCRIPTION("DRM SHMEM memory-management helpers"); > MODULE_IMPORT_NS("DMA_BUF"); > MODULE_LICENSE("GPL v2"); > diff --git a/drivers/gpu/drm/drm_prime.c b/drivers/gpu/drm/drm_prime.c > index d828502268b8..5bcf483520b8 100644 > --- a/drivers/gpu/drm/drm_prime.c > +++ b/drivers/gpu/drm/drm_prime.c > @@ -910,6 +910,26 @@ struct dma_buf *drm_gem_prime_export(struct drm_gem_object *obj, > } > EXPORT_SYMBOL(drm_gem_prime_export); > > + > +/** > + * drm_gem_prime_exported_dma_buf - > + * checks if the DMA-BUF was exported from a GEM object belonging to @dev. > + * @dev: drm_device to check against > + * @dma_buf: dma-buf object to import > + * > + * Return: true if the DMA-BUF was exported from a GEM object belonging > + * to @dev, false otherwise. > + */ > + > +bool drm_gem_prime_exported_dma_buf(struct drm_device *dev, > + struct dma_buf *dma_buf) If I remember the naming conventions correctly this should be something like drm_gem_is_prime_exported_dma_buf(). Regards, Christian. > +{ > + struct drm_gem_object *obj = dma_buf->priv; > + > + return (dma_buf->ops == &drm_gem_prime_dmabuf_ops) && (obj->dev == dev); > +} > +EXPORT_SYMBOL(drm_gem_prime_exported_dma_buf); > + > /** > * drm_gem_prime_import_dev - core implementation of the import callback > * @dev: drm_device to import into > @@ -933,16 +953,14 @@ struct drm_gem_object *drm_gem_prime_import_dev(struct drm_device *dev, > struct drm_gem_object *obj; > int ret; > > - if (dma_buf->ops == &drm_gem_prime_dmabuf_ops) { > + if (drm_gem_prime_exported_dma_buf(dev, dma_buf)) { > + /* > + * Importing dmabuf exported from our own gem increases > + * refcount on gem itself instead of f_count of dmabuf. > + */ > obj = dma_buf->priv; > - if (obj->dev == dev) { > - /* > - * Importing dmabuf exported from our own gem increases > - * refcount on gem itself instead of f_count of dmabuf. > - */ > - drm_gem_object_get(obj); > - return obj; > - } > + drm_gem_object_get(obj); > + return obj; > } > > if (!dev->driver->gem_prime_import_sg_table) > diff --git a/include/drm/drm_gem_shmem_helper.h b/include/drm/drm_gem_shmem_helper.h > index b4f993da3cae..9ee697ff52ea 100644 > --- a/include/drm/drm_gem_shmem_helper.h > +++ b/include/drm/drm_gem_shmem_helper.h > @@ -287,6 +287,8 @@ drm_gem_shmem_prime_import_sg_table(struct drm_device *dev, > struct sg_table *sgt); > int drm_gem_shmem_dumb_create(struct drm_file *file, struct drm_device *dev, > struct drm_mode_create_dumb *args); > +struct drm_gem_object *drm_gem_shmem_prime_import_no_sgt(struct drm_device *dev, > + struct dma_buf *buf); > > /** > * DRM_GEM_SHMEM_DRIVER_OPS - Default shmem GEM operations > @@ -298,4 +300,17 @@ int drm_gem_shmem_dumb_create(struct drm_file *file, struct drm_device *dev, > .gem_prime_import_sg_table = drm_gem_shmem_prime_import_sg_table, \ > .dumb_create = drm_gem_shmem_dumb_create > > +/** > + * DRM_GEM_SHMEM_DRIVER_OPS_NO_SGT - shmem GEM operations > + * without mapping sg_table on > + * imported buffer. > + * > + * This macro provides a shortcut for setting the shmem GEM operations in > + * the &drm_driver structure for drivers that do not require a sg_table on > + * imported buffers. > + */ > +#define DRM_GEM_SHMEM_DRIVER_OPS_NO_SGT \ > + .gem_prime_import = drm_gem_shmem_prime_import_no_sgt, \ > + .dumb_create = drm_gem_shmem_dumb_create > + > #endif /* __DRM_GEM_SHMEM_HELPER_H__ */ > diff --git a/include/drm/drm_prime.h b/include/drm/drm_prime.h > index fa085c44d4ca..ec83f1c077a4 100644 > --- a/include/drm/drm_prime.h > +++ b/include/drm/drm_prime.h > @@ -100,6 +100,9 @@ struct dma_buf *drm_gem_prime_export(struct drm_gem_object *obj, > unsigned long drm_prime_get_contiguous_size(struct sg_table *sgt); > > /* helper functions for importing */ > +bool drm_gem_prime_exported_dma_buf(struct drm_device *dev, > + struct dma_buf *dma_buf); > + > struct drm_gem_object *drm_gem_prime_import_dev(struct drm_device *dev, > struct dma_buf *dma_buf, > struct device *attach_dev);