[PATCHv3 2/3] drm/prime: Introduce drm_gem_prime_import_platform

[Laura Abbott]

The existing drm_gem_prime_import function uses the underlying
struct device of a drm_device for attaching to a dma_buf. Some drivers
(notably vgem) may not have an underlying device structure. Offer
an alternate function to attach using a platform device associated
with drm_device.

Cc: intel-gfx@xxxxxxxxxxxxxxxxxxxxx
Reviewed-by: Chris Wilson <chris@xxxxxxxxxxxxxxxxxx>
Signed-off-by: Laura Abbott <labbott@xxxxxxxxxx>
---
v3: Rebase to drm-misc-next. Prototype moved to a new header file. Comments
added for new function. Brought back drm_device->platformdev as it had been
removed in 76adb460fd93 ("drm: Remove the struct drm_device platformdev field").
I'm not entirely thrilled about this since the platformdev removal was good
cleanup and this feels like a small step backwards. I don't know of a better
approach though.
---
 drivers/gpu/drm/drm_prime.c | 49 +++++++++++++++++++++++++++++++++++----------
 include/drm/drmP.h          |  2 ++
 include/drm/drm_prime.h     |  4 ++++
 3 files changed, 44 insertions(+), 11 deletions(-)

diff --git a/drivers/gpu/drm/drm_prime.c b/drivers/gpu/drm/drm_prime.c
index 9fb65b7..a557a4b 100644
--- a/drivers/gpu/drm/drm_prime.c
+++ b/drivers/gpu/drm/drm_prime.c
@@ -594,16 +594,9 @@ int drm_gem_prime_handle_to_fd(struct drm_device *dev,
 }
 EXPORT_SYMBOL(drm_gem_prime_handle_to_fd);
 
-/**
- * drm_gem_prime_import - helper library implementation of the import callback
- * @dev: drm_device to import into
- * @dma_buf: dma-buf object to import
- *
- * This is the implementation of the gem_prime_import functions for GEM drivers
- * using the PRIME helpers.
- */
-struct drm_gem_object *drm_gem_prime_import(struct drm_device *dev,
-					    struct dma_buf *dma_buf)
+static struct drm_gem_object *__drm_gem_prime_import(struct drm_device *dev,
+					    struct dma_buf *dma_buf,
+					    struct device *attach_dev)
 {
 	struct dma_buf_attachment *attach;
 	struct sg_table *sgt;
@@ -625,7 +618,7 @@ struct drm_gem_object *drm_gem_prime_import(struct drm_device *dev,
 	if (!dev->driver->gem_prime_import_sg_table)
 		return ERR_PTR(-EINVAL);
 
-	attach = dma_buf_attach(dma_buf, dev->dev);
+	attach = dma_buf_attach(dma_buf, attach_dev);
 	if (IS_ERR(attach))
 		return ERR_CAST(attach);
 
@@ -655,9 +648,43 @@ struct drm_gem_object *drm_gem_prime_import(struct drm_device *dev,
 
 	return ERR_PTR(ret);
 }
+
+/**
+ * drm_gem_prime_import - helper library implementation of the import callback
+ * @dev: drm_device to import into
+ * @dma_buf: dma-buf object to import
+ *
+ * This is the implementation of the gem_prime_import functions for GEM drivers
+ * using the PRIME helpers.
+ */
+struct drm_gem_object *drm_gem_prime_import(struct drm_device *dev,
+					    struct dma_buf *dma_buf)
+{
+	return __drm_gem_prime_import(dev, dma_buf, dev->dev);
+}
 EXPORT_SYMBOL(drm_gem_prime_import);
 
 /**
+ * drm_gem_prime_import_platform - alternate implementation of the import callback
+ * @dev: drm_device to import into
+ * @dma_buf: dma-buf object to import
+ *
+ * This is identical to drm_gem_prime_import except the device used for dma_buf
+ * attachment is an internal platform device instead of the standard device
+ * structure. The use of this function should be limited to drivers that do not
+ * set up an underlying device structure.
+ */
+struct drm_gem_object *drm_gem_prime_import_platform(struct drm_device *dev,
+					    struct dma_buf *dma_buf)
+{
+	if (WARN_ON_ONCE(!dev->platformdev))
+		return NULL;
+
+	return __drm_gem_prime_import(dev, dma_buf, &dev->platformdev->dev);
+}
+EXPORT_SYMBOL(drm_gem_prime_import_platform);
+
+/**
  * drm_gem_prime_fd_to_handle - PRIME import function for GEM drivers
  * @dev: dev to export the buffer from
  * @file_priv: drm file-private structure
diff --git a/include/drm/drmP.h b/include/drm/drmP.h
index e1daa4f..086daee 100644
--- a/include/drm/drmP.h
+++ b/include/drm/drmP.h
@@ -439,6 +439,8 @@ struct drm_device {
 	struct pci_controller *hose;
 #endif
 
+	/**< Platform device for drivers that do not use the standard device */
+	struct platform_device *platformdev;
 	struct virtio_device *virtdev;
 
 	struct drm_sg_mem *sg;	/**< Scatter gather memory */
diff --git a/include/drm/drm_prime.h b/include/drm/drm_prime.h
index 0b2a235..9fe39f8 100644
--- a/include/drm/drm_prime.h
+++ b/include/drm/drm_prime.h
@@ -65,6 +65,10 @@ int drm_gem_prime_handle_to_fd(struct drm_device *dev,
 			       int *prime_fd);
 struct drm_gem_object *drm_gem_prime_import(struct drm_device *dev,
 					    struct dma_buf *dma_buf);
+
+struct drm_gem_object *drm_gem_prime_import_platform(struct drm_device *dev,
+						     struct dma_buf *dma_buf);
+
 int drm_gem_prime_fd_to_handle(struct drm_device *dev,
 			       struct drm_file *file_priv, int prime_fd, uint32_t *handle);
 struct dma_buf *drm_gem_dmabuf_export(struct drm_device *dev,
-- 
2.7.4