[PATCH 3/3] drm/amdgpu: Add documentation for PRIME related code
Michel Dänzer
michel at daenzer.net
Thu May 31 16:17:08 UTC 2018
From: Michel Dänzer <michel.daenzer at amd.com>
Signed-off-by: Michel Dänzer <michel.daenzer at amd.com>
---
Documentation/gpu/amdgpu.rst | 14 +++
drivers/gpu/drm/amd/amdgpu/amdgpu_prime.c | 119 ++++++++++++++++++++++
2 files changed, 133 insertions(+)
diff --git a/Documentation/gpu/amdgpu.rst b/Documentation/gpu/amdgpu.rst
index 41a14e4aa4ac..f557866f6788 100644
--- a/Documentation/gpu/amdgpu.rst
+++ b/Documentation/gpu/amdgpu.rst
@@ -4,3 +4,17 @@
The drm/amdgpu driver supports all AMD Radeon GPUs based on the Graphics Core
Next (GCN) architecture.
+
+Core Driver Infrastructure
+==========================
+
+This section covers core driver infrastructure.
+
+PRIME Buffer Sharing
+--------------------
+
+.. kernel-doc:: drivers/gpu/drm/amd/amdgpu/amdgpu_prime.c
+ :doc: PRIME Buffer Sharing
+
+.. kernel-doc:: drivers/gpu/drm/amd/amdgpu/amdgpu_prime.c
+ :internal:
diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_prime.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_prime.c
index 4683626b065f..d1f05489595b 100644
--- a/drivers/gpu/drm/amd/amdgpu/amdgpu_prime.c
+++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_prime.c
@@ -23,6 +23,14 @@
*
* Authors: Alex Deucher
*/
+
+/**
+ * DOC: PRIME Buffer Sharing
+ *
+ * The following callback implementations are used for :ref:`sharing GEM buffer
+ * objects between different devices via PRIME <prime_buffer_sharing>`.
+ */
+
#include <drm/drmP.h>
#include "amdgpu.h"
@@ -32,6 +40,14 @@
static const struct dma_buf_ops amdgpu_dmabuf_ops;
+/**
+ * amdgpu_gem_prime_get_sg_table - &drm_driver.gem_prime_get_sg_table
+ * implementation
+ * @obj: GEM buffer object
+ *
+ * Returns:
+ * A scatter/gather table for the pinned pages of the buffer object's memory.
+ */
struct sg_table *amdgpu_gem_prime_get_sg_table(struct drm_gem_object *obj)
{
struct amdgpu_bo *bo = gem_to_amdgpu_bo(obj);
@@ -40,6 +56,15 @@ struct sg_table *amdgpu_gem_prime_get_sg_table(struct drm_gem_object *obj)
return drm_prime_pages_to_sg(bo->tbo.ttm->pages, npages);
}
+/**
+ * amdgpu_gem_prime_vmap - &dma_buf_ops.vmap implementation
+ * @obj: GEM buffer object
+ *
+ * Sets up an in-kernel virtual mapping of the buffer object's memory.
+ *
+ * Returns:
+ * The virtual address of the mapping or an error pointer.
+ */
void *amdgpu_gem_prime_vmap(struct drm_gem_object *obj)
{
struct amdgpu_bo *bo = gem_to_amdgpu_bo(obj);
@@ -53,6 +78,13 @@ void *amdgpu_gem_prime_vmap(struct drm_gem_object *obj)
return bo->dma_buf_vmap.virtual;
}
+/**
+ * amdgpu_gem_prime_vunmap - &dma_buf_ops.vunmap implementation
+ * @obj: GEM buffer object
+ * @vaddr: virtual address (unused)
+ *
+ * Tears down the in-kernel virtual mapping of the buffer object's memory.
+ */
void amdgpu_gem_prime_vunmap(struct drm_gem_object *obj, void *vaddr)
{
struct amdgpu_bo *bo = gem_to_amdgpu_bo(obj);
@@ -60,6 +92,17 @@ void amdgpu_gem_prime_vunmap(struct drm_gem_object *obj, void *vaddr)
ttm_bo_kunmap(&bo->dma_buf_vmap);
}
+/**
+ * amdgpu_gem_prime_mmap - &drm_driver.gem_prime_mmap implementation
+ * @obj: GEM buffer object
+ * @vma: virtual memory area
+ *
+ * Sets up a userspace mapping of the buffer object's memory in the given
+ * virtual memory area.
+ *
+ * Returns:
+ * 0 on success or negative error code.
+ */
int amdgpu_gem_prime_mmap(struct drm_gem_object *obj, struct vm_area_struct *vma)
{
struct amdgpu_bo *bo = gem_to_amdgpu_bo(obj);
@@ -94,6 +137,19 @@ int amdgpu_gem_prime_mmap(struct drm_gem_object *obj, struct vm_area_struct *vma
return ret;
}
+/**
+ * amdgpu_gem_prime_import_sg_table - &drm_driver.gem_prime_import_sg_table
+ * implementation
+ * @dev: DRM device
+ * @attach: DMA-buf attachment
+ * @sg: Scatter/gather table
+ *
+ * Import shared DMA buffer memory exported by another device.
+ *
+ * Returns:
+ * A new GEM buffer object of the given DRM device, representing the memory
+ * described by the given DMA-buf attachment and scatter/gather table.
+ */
struct drm_gem_object *
amdgpu_gem_prime_import_sg_table(struct drm_device *dev,
struct dma_buf_attachment *attach,
@@ -132,6 +188,19 @@ amdgpu_gem_prime_import_sg_table(struct drm_device *dev,
return ERR_PTR(ret);
}
+/**
+ * amdgpu_gem_map_attach - &dma_buf_ops.attach implementation
+ * @dma_buf: shared DMA buffer
+ * @target_dev: target device
+ * @attach: DMA-buf attachment
+ *
+ * Makes sure that the shared DMA buffer can be accessed by the target device.
+ * For now, simply pins it to the GTT domain, where it should be accessible by
+ * all DMA devices.
+ *
+ * Returns:
+ * 0 on success or negative error code.
+ */
static int amdgpu_gem_map_attach(struct dma_buf *dma_buf,
struct device *target_dev,
struct dma_buf_attachment *attach)
@@ -181,6 +250,14 @@ static int amdgpu_gem_map_attach(struct dma_buf *dma_buf,
return r;
}
+/**
+ * amdgpu_gem_map_detach - &dma_buf_ops.detach implementation
+ * @dma_buf: shared DMA buffer
+ * @attach: DMA-buf attachment
+ *
+ * This is called when a shared DMA buffer no longer needs to be accessible by
+ * the other device. For now, simply unpins the buffer from GTT.
+ */
static void amdgpu_gem_map_detach(struct dma_buf *dma_buf,
struct dma_buf_attachment *attach)
{
@@ -202,6 +279,13 @@ static void amdgpu_gem_map_detach(struct dma_buf *dma_buf,
drm_gem_map_detach(dma_buf, attach);
}
+/**
+ * amdgpu_gem_prime_res_obj - &drm_driver.gem_prime_res_obj implementation
+ * @obj: GEM buffer object
+ *
+ * Returns:
+ * The buffer object's reservation object.
+ */
struct reservation_object *amdgpu_gem_prime_res_obj(struct drm_gem_object *obj)
{
struct amdgpu_bo *bo = gem_to_amdgpu_bo(obj);
@@ -209,6 +293,18 @@ struct reservation_object *amdgpu_gem_prime_res_obj(struct drm_gem_object *obj)
return bo->tbo.resv;
}
+/**
+ * amdgpu_gem_begin_cpu_access - &dma_buf_ops.begin_cpu_access implementation
+ * @dma_buf: shared DMA buffer
+ * @direction: direction of DMA transfer
+ *
+ * This is called before CPU access to the shared DMA buffer's memory. If it's
+ * a read access, the buffer is moved to the GTT domain if possible, for optimal
+ * CPU read performance.
+ *
+ * Returns:
+ * 0 on success or negative error code.
+ */
static int amdgpu_gem_begin_cpu_access(struct dma_buf *dma_buf,
enum dma_data_direction direction)
{
@@ -253,6 +349,18 @@ static const struct dma_buf_ops amdgpu_dmabuf_ops = {
.vunmap = drm_gem_dmabuf_vunmap,
};
+/**
+ * amdgpu_gem_prime_export - &drm_driver.gem_prime_export implementation
+ * @dev: DRM device
+ * @gobj: GEM buffer object
+ * @flags: flags like DRM_CLOEXEC and DRM_RDWR
+ *
+ * The main work is done by the &drm_gem_prime_export helper, which in turn
+ * uses &amdgpu_gem_prime_res_obj.
+ *
+ * Returns:
+ * Shared DMA buffer representing the GEM buffer object from the given device.
+ */
struct dma_buf *amdgpu_gem_prime_export(struct drm_device *dev,
struct drm_gem_object *gobj,
int flags)
@@ -273,6 +381,17 @@ struct dma_buf *amdgpu_gem_prime_export(struct drm_device *dev,
return buf;
}
+/**
+ * amdgpu_gem_prime_import - &drm_driver.gem_prime_import implementation
+ * @dev: DRM device
+ * @dma_buf: Shared DMA buffer
+ *
+ * The main work is done by the &drm_gem_prime_import helper, which in turn
+ * uses &amdgpu_gem_prime_import_sg_table.
+ *
+ * Returns:
+ * GEM buffer object representing the shared DMA buffer for the given device.
+ */
struct drm_gem_object *amdgpu_gem_prime_import(struct drm_device *dev,
struct dma_buf *dma_buf)
{
--
2.17.0
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