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 <faith.ekstr...@collabora.com>
---
drivers/gpu/drm/drm_gem_shmem_helper.c | 64 ++++++++++++++++++++++++++
include/drm/drm_gem_shmem_helper.h | 3 ++
2 files changed, 67 insertions(+)
diff --git a/drivers/gpu/drm/drm_gem_shmem_helper.c
b/drivers/gpu/drm/drm_gem_shmem_helper.c
index 8ac0b1fa5287..50907c1fa11f 100644
--- a/drivers/gpu/drm/drm_gem_shmem_helper.c
+++ b/drivers/gpu/drm/drm_gem_shmem_helper.c
@@ -658,6 +658,70 @@ 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_mmap - Sync memor-mapped data to/from the device
+ * @shmem: shmem GEM object
+ * @offset: Offset into the GEM object
+ * @size: Size of the area to sync
+ *
+ * Returns:
+ * 0 on success or a negative error code on failure.
+ */
+int
+drm_gem_shmem_sync_mmap(struct drm_gem_shmem_object *shmem,
+ size_t offset, size_t size,
+ enum dma_data_direction dir)
+{
+ struct drm_device *dev = shmem->base.dev;
+ struct sg_table *sgt;
+ struct scatterlist *sgl;
+ unsigned int count;
+
+ if (dir == DMA_NONE)
+ return 0;
+
+ /* Don't bother if it's WC-mapped */
+ if (shmem->map_wc)
+ return 0;
+
+ if (size == 0)
+ return 0;
+
+ if (offset + size < offset || offset + size > shmem->base.size)
+ return -EINVAL;
+
+ 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;
+
+ if (dir == DMA_FROM_DEVICE)
+ dma_sync_single_for_cpu(dev->dev, paddr, len, dir);
+ else
+ dma_sync_single_for_device(dev->dev, paddr, len, dir);
+ }
+
+ return 0;
+}
+EXPORT_SYMBOL_GPL(drm_gem_shmem_sync_mmap);
+
/**
* 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 92f5db84b9c2..8e057a8e6c83 100644
--- a/include/drm/drm_gem_shmem_helper.h
+++ b/include/drm/drm_gem_shmem_helper.h
@@ -121,6 +121,9 @@ int drm_gem_shmem_vmap_locked(struct drm_gem_shmem_object
*shmem,
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);
+int drm_gem_shmem_sync_mmap(struct drm_gem_shmem_object *shmem,
+ size_t offset, size_t size,
+ enum dma_data_direction dir);
int drm_gem_shmem_pin_locked(struct drm_gem_shmem_object *shmem);
void drm_gem_shmem_unpin_locked(struct drm_gem_shmem_object *shmem);
--
2.50.1
