From: Faith Ekstrand <[email protected]> This enables syncing mapped GEM objects between the CPU and GPU via calls to dma_sync_*(). It's a bit annoying as it requires walking the sg_table so it's best if every driver doesn't hand-roll it.
Signed-off-by: Faith Ekstrand <[email protected]> Signed-off-by: Boris Brezillon <[email protected]> Reviewed-by: Steven Price <[email protected]> [mcanal: rebased on top of drm-misc-next and fixed a kernel-doc nit] Signed-off-by: Maíra Canal <[email protected]> --- drivers/gpu/drm/drm_gem_shmem_helper.c | 93 ++++++++++++++++++++++++++++++++++ include/drm/drm_gem_shmem_helper.h | 17 +++++++ 2 files changed, 110 insertions(+) diff --git a/drivers/gpu/drm/drm_gem_shmem_helper.c b/drivers/gpu/drm/drm_gem_shmem_helper.c index 13c4a68fdde0..9bf727fc1c19 100644 --- a/drivers/gpu/drm/drm_gem_shmem_helper.c +++ b/drivers/gpu/drm/drm_gem_shmem_helper.c @@ -790,6 +790,99 @@ int drm_gem_shmem_mmap(struct drm_gem_shmem_object *shmem, struct vm_area_struct } EXPORT_SYMBOL_GPL(drm_gem_shmem_mmap); +/** + * drm_gem_shmem_sync - Sync CPU-mapped data + * @shmem: shmem GEM object + * @offset: Offset into the GEM object + * @size: Size of the area to sync + * @type: Type of synchronization + * + * Returns: + * 0 on success or a negative error code on failure. + */ +int drm_gem_shmem_sync(struct drm_gem_shmem_object *shmem, size_t offset, + size_t size, enum drm_gem_shmem_sync_type type) +{ + const struct drm_device *dev = shmem->base.dev; + struct sg_table *sgt; + struct scatterlist *sgl; + unsigned int count; + + /* Make sure the range is in bounds. */ + if (offset + size < offset || offset + size > shmem->base.size) + return -EINVAL; + + /* Disallow CPU-cache maintenance on imported buffers. */ + if (drm_gem_is_imported(&shmem->base)) + return -EINVAL; + + switch (type) { + case DRM_GEM_SHMEM_SYNC_CPU_CACHE_FLUSH: + case DRM_GEM_SHMEM_SYNC_CPU_CACHE_FLUSH_AND_INVALIDATE: + break; + + default: + return -EINVAL; + } + + /* Don't bother if it's WC-mapped */ + if (shmem->map_wc) + return 0; + + /* Nothing to do if the size is zero. */ + if (size == 0) + return 0; + + sgt = drm_gem_shmem_get_pages_sgt(shmem); + if (IS_ERR(sgt)) + return PTR_ERR(sgt); + + for_each_sgtable_dma_sg(sgt, sgl, count) { + if (size == 0) + break; + + dma_addr_t paddr = sg_dma_address(sgl); + size_t len = sg_dma_len(sgl); + + if (len <= offset) { + offset -= len; + continue; + } + + paddr += offset; + len -= offset; + len = min_t(size_t, len, size); + size -= len; + offset = 0; + + /* It's unclear whether dma_sync_xxx() is the right API to do CPU + * cache maintenance given an IOMMU can register their own + * implementation doing more than just CPU cache flushes/invalidation, + * and what we really care about here is CPU caches only, but that's + * the best we have that is both arch-agnostic and does at least the + * CPU cache maintenance on a <page,offset,size> tuple. + * + * Also, I wish we could do a single + * + * dma_sync_single_for_device(BIDIR) + * + * and get a flush+invalidate, but that's not how it's implemented + * in practice (at least on arm64), so we have to make it + * + * dma_sync_single_for_device(TO_DEVICE) + * dma_sync_single_for_cpu(FROM_DEVICE) + * + * for the flush+invalidate case. + */ + dma_sync_single_for_device(dev->dev, paddr, len, DMA_TO_DEVICE); + if (type == DRM_GEM_SHMEM_SYNC_CPU_CACHE_FLUSH_AND_INVALIDATE) + dma_sync_single_for_cpu(dev->dev, paddr, len, DMA_FROM_DEVICE); + } + + return 0; +} +EXPORT_SYMBOL_GPL(drm_gem_shmem_sync); + /** * drm_gem_shmem_print_info() - Print &drm_gem_shmem_object info for debugfs * @shmem: shmem GEM object diff --git a/include/drm/drm_gem_shmem_helper.h b/include/drm/drm_gem_shmem_helper.h index 358cd247f803..3c6ed3a5f0ac 100644 --- a/include/drm/drm_gem_shmem_helper.h +++ b/include/drm/drm_gem_shmem_helper.h @@ -122,6 +122,23 @@ void drm_gem_shmem_vunmap_locked(struct drm_gem_shmem_object *shmem, struct iosys_map *map); int drm_gem_shmem_mmap(struct drm_gem_shmem_object *shmem, struct vm_area_struct *vma); +/** + * enum drm_gem_shmem_sync_type - Type of synchronization + */ +enum drm_gem_shmem_sync_type { + /** @DRM_GEM_SHMEM_SYNC_CPU_CACHE_FLUSH: Flush CPU caches */ + DRM_GEM_SHMEM_SYNC_CPU_CACHE_FLUSH = 0, + + /** + * @DRM_GEM_SHMEM_SYNC_CPU_CACHE_FLUSH_AND_INVALIDATE: Flush and + * invalidate CPU caches + */ + DRM_GEM_SHMEM_SYNC_CPU_CACHE_FLUSH_AND_INVALIDATE, +}; + +int drm_gem_shmem_sync(struct drm_gem_shmem_object *shmem, size_t offset, + size_t size, enum drm_gem_shmem_sync_type type); + int drm_gem_shmem_pin_locked(struct drm_gem_shmem_object *shmem); void drm_gem_shmem_unpin_locked(struct drm_gem_shmem_object *shmem); -- 2.56.0
