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drm/cma-helper: Pass GEM CMA object in public interfaces
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Change all GEM CMA object functions that receive a GEM object
of type struct drm_gem_object to expect an object of type
struct drm_gem_cma_object instead.

This change reduces the number of upcasts from struct drm_gem_object
by moving them into callers. The C compiler can now verify that the
GEM CMA functions are called with the correct type.

For consistency, the patch also renames drm_gem_cma_free_object to
drm_gem_cma_free. It further updates documentation for a number of
functions.

Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de>
Reviewed-by: Maxime Ripard <maxime@cerno.tech>
Link: https://patchwork.freedesktop.org/patch/msgid/20211115120148.21766-4-tzimmermann@suse.de
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Thomas Zimmermann committed Nov 30, 2021
1 parent 05b1de5 commit e580ea2
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Showing 3 changed files with 48 additions and 47 deletions.
52 changes: 24 additions & 28 deletions drivers/gpu/drm/drm_gem_cma_helper.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -32,6 +32,10 @@
* The DRM GEM/CMA helpers use this allocator as a means to provide buffer
* objects that are physically contiguous in memory. This is useful for
* display drivers that are unable to map scattered buffers via an IOMMU.
*
* For GEM callback helpers in struct &drm_gem_object functions, see likewise
* named functions with an _object_ infix (e.g., drm_gem_cma_object_vmap() wraps
* drm_gem_cma_vmap()). These helpers perform the necessary type conversion.
*/

static const struct drm_gem_object_funcs drm_gem_cma_default_funcs = {
Expand Down Expand Up @@ -192,16 +196,16 @@ drm_gem_cma_create_with_handle(struct drm_file *file_priv,
}

/**
* drm_gem_cma_free_object - free resources associated with a CMA GEM object
* @gem_obj: GEM object to free
* drm_gem_cma_free - free resources associated with a CMA GEM object
* @cma_obj: CMA GEM object to free
*
* This function frees the backing memory of the CMA GEM object, cleans up the
* GEM object state and frees the memory used to store the object itself.
* If the buffer is imported and the virtual address is set, it is released.
*/
void drm_gem_cma_free_object(struct drm_gem_object *gem_obj)
void drm_gem_cma_free(struct drm_gem_cma_object *cma_obj)
{
struct drm_gem_cma_object *cma_obj = to_drm_gem_cma_obj(gem_obj);
struct drm_gem_object *gem_obj = &cma_obj->base;
struct dma_buf_map map = DMA_BUF_MAP_INIT_VADDR(cma_obj->vaddr);

if (gem_obj->import_attach) {
Expand All @@ -217,7 +221,7 @@ void drm_gem_cma_free_object(struct drm_gem_object *gem_obj)

kfree(cma_obj);
}
EXPORT_SYMBOL_GPL(drm_gem_cma_free_object);
EXPORT_SYMBOL_GPL(drm_gem_cma_free);

/**
* drm_gem_cma_dumb_create_internal - create a dumb buffer object
Expand Down Expand Up @@ -364,18 +368,15 @@ EXPORT_SYMBOL_GPL(drm_gem_cma_get_unmapped_area);

/**
* drm_gem_cma_print_info() - Print &drm_gem_cma_object info for debugfs
* @cma_obj: CMA GEM object
* @p: DRM printer
* @indent: Tab indentation level
* @obj: GEM object
*
* This function can be used as the &drm_driver->gem_print_info callback.
* It prints paddr and vaddr for use in e.g. debugfs output.
* This function prints paddr and vaddr for use in e.g. debugfs output.
*/
void drm_gem_cma_print_info(struct drm_printer *p, unsigned int indent,
const struct drm_gem_object *obj)
void drm_gem_cma_print_info(const struct drm_gem_cma_object *cma_obj,
struct drm_printer *p, unsigned int indent)
{
const struct drm_gem_cma_object *cma_obj = to_drm_gem_cma_obj(obj);

drm_printf_indent(p, indent, "paddr=%pad\n", &cma_obj->paddr);
drm_printf_indent(p, indent, "vaddr=%p\n", cma_obj->vaddr);
}
Expand All @@ -384,17 +385,17 @@ EXPORT_SYMBOL(drm_gem_cma_print_info);
/**
* drm_gem_cma_get_sg_table - provide a scatter/gather table of pinned
* pages for a CMA GEM object
* @obj: GEM object
* @cma_obj: CMA GEM object
*
* This function exports a scatter/gather table by calling the standard
* DMA mapping API.
*
* Returns:
* A pointer to the scatter/gather table of pinned pages or NULL on failure.
*/
struct sg_table *drm_gem_cma_get_sg_table(struct drm_gem_object *obj)
struct sg_table *drm_gem_cma_get_sg_table(struct drm_gem_cma_object *cma_obj)
{
struct drm_gem_cma_object *cma_obj = to_drm_gem_cma_obj(obj);
struct drm_gem_object *obj = &cma_obj->base;
struct sg_table *sgt;
int ret;

Expand Down Expand Up @@ -460,22 +461,19 @@ EXPORT_SYMBOL_GPL(drm_gem_cma_prime_import_sg_table);
/**
* drm_gem_cma_vmap - map a CMA GEM object into the kernel's virtual
* address space
* @obj: GEM object
* @cma_obj: CMA GEM object
* @map: Returns the kernel virtual address of the CMA GEM object's backing
* store.
*
* This function maps a buffer into the kernel's
* virtual address space. Since the CMA buffers are already mapped into the
* kernel virtual address space this simply returns the cached virtual
* address.
* This function maps a buffer into the kernel's virtual address space.
* Since the CMA buffers are already mapped into the kernel virtual address
* space this simply returns the cached virtual address.
*
* Returns:
* 0 on success, or a negative error code otherwise.
*/
int drm_gem_cma_vmap(struct drm_gem_object *obj, struct dma_buf_map *map)
int drm_gem_cma_vmap(struct drm_gem_cma_object *cma_obj, struct dma_buf_map *map)
{
struct drm_gem_cma_object *cma_obj = to_drm_gem_cma_obj(obj);

dma_buf_map_set_vaddr(map, cma_obj->vaddr);

return 0;
Expand All @@ -484,7 +482,7 @@ EXPORT_SYMBOL_GPL(drm_gem_cma_vmap);

/**
* drm_gem_cma_mmap - memory-map an exported CMA GEM object
* @obj: GEM object
* @cma_obj: CMA GEM object
* @vma: VMA for the area to be mapped
*
* This function maps a buffer into a userspace process's address space.
Expand All @@ -494,9 +492,9 @@ EXPORT_SYMBOL_GPL(drm_gem_cma_vmap);
* Returns:
* 0 on success or a negative error code on failure.
*/
int drm_gem_cma_mmap(struct drm_gem_object *obj, struct vm_area_struct *vma)
int drm_gem_cma_mmap(struct drm_gem_cma_object *cma_obj, struct vm_area_struct *vma)
{
struct drm_gem_cma_object *cma_obj;
struct drm_gem_object *obj = &cma_obj->base;
int ret;

/*
Expand All @@ -507,8 +505,6 @@ int drm_gem_cma_mmap(struct drm_gem_object *obj, struct vm_area_struct *vma)
vma->vm_pgoff -= drm_vma_node_start(&obj->vma_node);
vma->vm_flags &= ~VM_PFNMAP;

cma_obj = to_drm_gem_cma_obj(obj);

if (cma_obj->map_noncoherent) {
vma->vm_page_prot = vm_get_page_prot(vma->vm_flags);

Expand Down
4 changes: 2 additions & 2 deletions drivers/gpu/drm/vc4/vc4_bo.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -177,7 +177,7 @@ static void vc4_bo_destroy(struct vc4_bo *bo)
bo->validated_shader = NULL;
}

drm_gem_cma_free_object(obj);
drm_gem_cma_free(&bo->base);
}

static void vc4_bo_remove_from_cache(struct vc4_bo *bo)
Expand Down Expand Up @@ -720,7 +720,7 @@ static int vc4_gem_object_mmap(struct drm_gem_object *obj, struct vm_area_struct
return -EINVAL;
}

return drm_gem_cma_mmap(obj, vma);
return drm_gem_cma_mmap(&bo->base, vma);
}

static const struct vm_operations_struct vc4_vm_ops = {
Expand Down
39 changes: 22 additions & 17 deletions include/drm/drm_gem_cma_helper.h
View file
Original file line number Diff line number Diff line change
Expand Up @@ -32,36 +32,33 @@ struct drm_gem_cma_object {
#define to_drm_gem_cma_obj(gem_obj) \
container_of(gem_obj, struct drm_gem_cma_object, base)

/* free GEM object */
void drm_gem_cma_free_object(struct drm_gem_object *gem_obj);

/* allocate physical memory */
struct drm_gem_cma_object *drm_gem_cma_create(struct drm_device *drm,
size_t size);
void drm_gem_cma_free(struct drm_gem_cma_object *cma_obj);
void drm_gem_cma_print_info(const struct drm_gem_cma_object *cma_obj,
struct drm_printer *p, unsigned int indent);
struct sg_table *drm_gem_cma_get_sg_table(struct drm_gem_cma_object *cma_obj);
int drm_gem_cma_vmap(struct drm_gem_cma_object *cma_obj, struct dma_buf_map *map);
int drm_gem_cma_mmap(struct drm_gem_cma_object *cma_obj, struct vm_area_struct *vma);

extern const struct vm_operations_struct drm_gem_cma_vm_ops;

void drm_gem_cma_print_info(struct drm_printer *p, unsigned int indent,
const struct drm_gem_object *obj);

struct sg_table *drm_gem_cma_get_sg_table(struct drm_gem_object *obj);
int drm_gem_cma_vmap(struct drm_gem_object *obj, struct dma_buf_map *map);
int drm_gem_cma_mmap(struct drm_gem_object *obj, struct vm_area_struct *vma);

/*
* GEM object functions
*/

/**
* drm_gem_cma_object_free - GEM object function for drm_gem_cma_free_object()
* drm_gem_cma_object_free - GEM object function for drm_gem_cma_free()
* @obj: GEM object to free
*
* This function wraps drm_gem_cma_free_object(). Drivers that employ the CMA helpers
* should use it as their &drm_gem_object_funcs.free handler.
*/
static inline void drm_gem_cma_object_free(struct drm_gem_object *obj)
{
drm_gem_cma_free_object(obj);
struct drm_gem_cma_object *cma_obj = to_drm_gem_cma_obj(obj);

drm_gem_cma_free(cma_obj);
}

/**
Expand All @@ -76,7 +73,9 @@ static inline void drm_gem_cma_object_free(struct drm_gem_object *obj)
static inline void drm_gem_cma_object_print_info(struct drm_printer *p, unsigned int indent,
const struct drm_gem_object *obj)
{
drm_gem_cma_print_info(p, indent, obj);
const struct drm_gem_cma_object *cma_obj = to_drm_gem_cma_obj(obj);

drm_gem_cma_print_info(cma_obj, p, indent);
}

/**
Expand All @@ -91,7 +90,9 @@ static inline void drm_gem_cma_object_print_info(struct drm_printer *p, unsigned
*/
static inline struct sg_table *drm_gem_cma_object_get_sg_table(struct drm_gem_object *obj)
{
return drm_gem_cma_get_sg_table(obj);
struct drm_gem_cma_object *cma_obj = to_drm_gem_cma_obj(obj);

return drm_gem_cma_get_sg_table(cma_obj);
}

/*
Expand All @@ -107,7 +108,9 @@ static inline struct sg_table *drm_gem_cma_object_get_sg_table(struct drm_gem_ob
*/
static inline int drm_gem_cma_object_vmap(struct drm_gem_object *obj, struct dma_buf_map *map)
{
return drm_gem_cma_vmap(obj, map);
struct drm_gem_cma_object *cma_obj = to_drm_gem_cma_obj(obj);

return drm_gem_cma_vmap(cma_obj, map);
}

/**
Expand All @@ -123,7 +126,9 @@ static inline int drm_gem_cma_object_vmap(struct drm_gem_object *obj, struct dma
*/
static inline int drm_gem_cma_object_mmap(struct drm_gem_object *obj, struct vm_area_struct *vma)
{
return drm_gem_cma_mmap(obj, vma);
struct drm_gem_cma_object *cma_obj = to_drm_gem_cma_obj(obj);

return drm_gem_cma_mmap(cma_obj, vma);
}

/*
Expand Down

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