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drm/amdgpu: Add documentation for PRIME related code

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Reviewed-by: Alex Deucher <alexander.deucher@amd.com>
Signed-off-by: Michel Dänzer <michel.daenzer@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
This commit is contained in:
Michel Dänzer 2018-05-29 18:33:41 +02:00 committed by Alex Deucher
parent 99fa7ce3a8
commit baca30fabd
2 changed files with 133 additions and 0 deletions
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14
Documentation/gpu/amdgpu.rst
View File

@ -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:

119
drivers/gpu/drm/amd/amdgpu/amdgpu_prime.c
View File

@ -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)
{