On 01/16/2013 01:50 AM, Daniel Vetter wrote:
On Tue, Jan 15, 2013 at 12:47:42PM -0800, Aaron Plattner wrote:
Instead of reimplementing all of the dma_buf functionality in every driver,
create helpers drm_prime_import and drm_prime_export that implement them in
terms of new, lower-level hook functions:
gem_prime_pin: callback when a buffer is created, used to pin buffers into GTT
gem_prime_get_sg_table: convert a drm_gem_object to an sg_table for export
gem_prime_import_sg_table: convert an sg_table into a drm_gem_object
gem_prime_vmap, gem_prime_vunmap: map and unmap an object
These hooks are optional; drivers can opt in by using drm_gem_prime_import and
drm_gem_prime_export as the .gem_prime_import and .gem_prime_export fields of
struct drm_driver.
v2:
- Drop .begin_cpu_access. None of the drivers this code replaces implemented
it. Having it here was a leftover from when I was trying to include i915 in
this rework.
- Use mutex_lock instead of mutex_lock_interruptible, as these three drivers
did. This patch series shouldn't change that behavior.
- Rename helpers to gem_prime_get_sg_table and gem_prime_import_sg_table.
Rename struct sg_table* variables to 'sgt' for clarity.
- Update drm.tmpl for these new hooks.
v3:
- Pass the vaddr down to the driver. This lets drivers that just call vunmap on
the pointer avoid having to store the pointer in their GEM private structures.
- Move documentation into a /** DOC */ comment in drm_prime.c and include it in
drm.tmpl with a !P line. I tried to use !F lines to include documentation of
the individual functions from drmP.h, but the docproc / kernel-doc scripts
barf on that file, so hopefully this is good enough for now.
- apply refcount fix from commit be8a42ae60addd8b6092535c11b42d099d6470ec
("drm/prime: drop reference on imported dma-buf come from gem")
Signed-off-by: Aaron Plattner <aplattner@xxxxxxxxxx>
Cc: Daniel Vetter <daniel.vetter@xxxxxxxx>
Cc: David Airlie <airlied@xxxxxxxx>
Two minor things, but since you're not touching drm/i915 I don't care that
much ...
+static struct sg_table *drm_gem_map_dma_buf(struct dma_buf_attachment *attach,
+ enum dma_data_direction dir)
+{
+ struct drm_gem_object *obj = attach->dmabuf->priv;
+ struct sg_table *sgt;
+
+ mutex_lock(&obj->dev->struct_mutex);
+
+ sgt = obj->dev->driver->gem_prime_get_sg_table(obj);
+
+ if (!IS_ERR_OR_NULL(sgt))
+ dma_map_sg(attach->dev, sgt->sgl, sgt->nents, dir);
+
+ mutex_unlock(&obj->dev->struct_mutex);
The locking here looks superflous and not required to protect anything
drm_gem_map_dma_buf does. If drivers need this (and ttm based ones
shouldn't really), they can grab it in their ->gem_prime_get_sg_table
callback. So I think a follow-up patch to ditch this would be good.
If you look at the later patches, this was just moved from the drivers.
I agree that evaluating whether or not it's actually necessary should
be a separate follow-up.
+ return sgt;
+}
+
+static void drm_gem_unmap_dma_buf(struct dma_buf_attachment *attach,
+ struct sg_table *sgt, enum dma_data_direction dir)
+{
+ dma_unmap_sg(attach->dev, sgt->sgl, sgt->nents, dir);
+ sg_free_table(sgt);
+ kfree(sgt);
+}
+
+static void drm_gem_dmabuf_release(struct dma_buf *dma_buf)
+{
+ struct drm_gem_object *obj = dma_buf->priv;
+
+ if (obj->export_dma_buf == dma_buf) {
+ /* drop the reference on the export fd holds */
+ obj->export_dma_buf = NULL;
+ drm_gem_object_unreference_unlocked(obj);
+ }
+}
+
+static void *drm_gem_dmabuf_vmap(struct dma_buf *dma_buf)
+{
+ struct drm_gem_object *obj = dma_buf->priv;
+ struct drm_device *dev = obj->dev;
+
+ return dev->driver->gem_prime_vmap(obj);
+}
+
+static void drm_gem_dmabuf_vunmap(struct dma_buf *dma_buf, void *vaddr)
+{
+ struct drm_gem_object *obj = dma_buf->priv;
+ struct drm_device *dev = obj->dev;
+
+ dev->driver->gem_prime_vunmap(obj, vaddr);
+}
Imo these two don't add value, simpler to add a typechecking
drm_dmabuf_to_gem_obj static inline somewhere. But then you'd need to pass
in the dmabuf fops struct from drivers and export the helpers. More
flexible, but also a bit work to redo. Like I've said, I don't care too
much ...
I considered that, but it seems like the wrong abstraction. The
advantage here is that drivers don't have to care even a little bit
about the buffer sharing mechanism, which simplifies the drivers.
I.e., from patch #2,
diff --git a/drivers/gpu/drm/nouveau/nouveau_gem.c
b/drivers/gpu/drm/nouveau/nouveau_gem.c
index 8bf695c..24e0aab 100644
--- a/drivers/gpu/drm/nouveau/nouveau_gem.c
+++ b/drivers/gpu/drm/nouveau/nouveau_gem.c
@@ -24,8 +24,6 @@
*
*/
-#include <linux/dma-buf.h>
Can I consider this a Reviewed-by?
--
Aaron
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