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

Signed-off-by: Boris Brezillon <[email protected]>
---
 drivers/gpu/drm/panthor/panthor_drv.c |  1 +
 drivers/gpu/drm/panthor/panthor_gem.c | 19 +++++++++++++++++++
 drivers/gpu/drm/panthor/panthor_gem.h |  3 +++
 3 files changed, 23 insertions(+)

diff --git a/drivers/gpu/drm/panthor/panthor_drv.c 
b/drivers/gpu/drm/panthor/panthor_drv.c
index fb4b293f17f0..99a4534c0074 100644
--- a/drivers/gpu/drm/panthor/panthor_drv.c
+++ b/drivers/gpu/drm/panthor/panthor_drv.c
@@ -1618,6 +1618,7 @@ static const struct drm_driver panthor_drm_driver = {
 
        .gem_create_object = panthor_gem_create_object,
        .gem_prime_import_sg_table = drm_gem_shmem_prime_import_sg_table,
+       .gem_prime_get_dma_buf_ops = panthor_gem_prime_get_dma_buf_ops,
 #ifdef CONFIG_DEBUG_FS
        .debugfs_init = panthor_debugfs_init,
 #endif
diff --git a/drivers/gpu/drm/panthor/panthor_gem.c 
b/drivers/gpu/drm/panthor/panthor_gem.c
index 156c7a0b62a2..160692e45f44 100644
--- a/drivers/gpu/drm/panthor/panthor_gem.c
+++ b/drivers/gpu/drm/panthor/panthor_gem.c
@@ -191,6 +191,25 @@ panthor_kernel_bo_create(struct panthor_device *ptdev, 
struct panthor_vm *vm,
        return ERR_PTR(ret);
 }
 
+static const struct dma_buf_ops panthor_dma_buf_ops = {
+       .attach = drm_gem_map_attach,
+       .detach = drm_gem_map_detach,
+       .map_dma_buf = drm_gem_shmem_prime_map_dma_buf,
+       .unmap_dma_buf = drm_gem_shmem_prime_unmap_dma_buf,
+       .release = drm_gem_dmabuf_release,
+       .mmap = drm_gem_dmabuf_mmap,
+       .vmap = drm_gem_dmabuf_vmap,
+       .vunmap = drm_gem_dmabuf_vunmap,
+       .begin_cpu_access = drm_gem_shmem_prime_begin_cpu_access,
+       .end_cpu_access = drm_gem_shmem_prime_end_cpu_access,
+};
+
+const struct dma_buf_ops *
+panthor_gem_prime_get_dma_buf_ops(struct drm_device *dev)
+{
+       return &panthor_dma_buf_ops;
+}
+
 static struct dma_buf *
 panthor_gem_prime_export(struct drm_gem_object *obj, int flags)
 {
diff --git a/drivers/gpu/drm/panthor/panthor_gem.h 
b/drivers/gpu/drm/panthor/panthor_gem.h
index 80c6e24112d0..528088839468 100644
--- a/drivers/gpu/drm/panthor/panthor_gem.h
+++ b/drivers/gpu/drm/panthor/panthor_gem.h
@@ -147,6 +147,9 @@ panthor_gem_create_with_handle(struct drm_file *file,
 void panthor_gem_bo_set_label(struct drm_gem_object *obj, const char *label);
 void panthor_gem_kernel_bo_set_label(struct panthor_kernel_bo *bo, const char 
*label);
 
+const struct dma_buf_ops *
+panthor_gem_prime_get_dma_buf_ops(struct drm_device *dev);
+
 static inline u64
 panthor_kernel_bo_gpuva(struct panthor_kernel_bo *bo)
 {
-- 
2.51.0

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