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@nvidia.com Cc: Daniel Vetter daniel.vetter@ffwll.ch Cc: David Airlie airlied@linux.ie
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?