This function can be used by drivers that need to create a GEM object with non-coherent backing memory.
Creating non-coherent CMA objects is useful on architectures where writing to a buffer with the non-coherent cache attribute set then invalidating the cache is faster than writing to the same buffer with the write-combine cache attribute set. This is the case for instance on some Ingenic SoCs.
v2: Add inline doc about why we need this, and improve commit message
Signed-off-by: Paul Cercueil paul@crapouillou.net --- drivers/gpu/drm/drm_gem_cma_helper.c | 76 +++++++++++++++++++++------- include/drm/drm_gem_cma_helper.h | 2 + 2 files changed, 61 insertions(+), 17 deletions(-)
diff --git a/drivers/gpu/drm/drm_gem_cma_helper.c b/drivers/gpu/drm/drm_gem_cma_helper.c index 7942cf05cd93..917b092b23c2 100644 --- a/drivers/gpu/drm/drm_gem_cma_helper.c +++ b/drivers/gpu/drm/drm_gem_cma_helper.c @@ -90,21 +90,10 @@ __drm_gem_cma_create(struct drm_device *drm, size_t size) return ERR_PTR(ret); }
-/** - * drm_gem_cma_create - allocate an object with the given size - * @drm: DRM device - * @size: size of the object to allocate - * - * This function creates a CMA GEM object and allocates a contiguous chunk of - * memory as backing store. The backing memory has the writecombine attribute - * set. - * - * Returns: - * A struct drm_gem_cma_object * on success or an ERR_PTR()-encoded negative - * error code on failure. - */ -struct drm_gem_cma_object *drm_gem_cma_create(struct drm_device *drm, - size_t size) +static struct drm_gem_cma_object * +drm_gem_cma_create_with_cache_param(struct drm_device *drm, + size_t size, + bool noncoherent) { struct drm_gem_cma_object *cma_obj; int ret; @@ -115,8 +104,16 @@ struct drm_gem_cma_object *drm_gem_cma_create(struct drm_device *drm, if (IS_ERR(cma_obj)) return cma_obj;
- cma_obj->vaddr = dma_alloc_wc(drm->dev, size, &cma_obj->paddr, - GFP_KERNEL | __GFP_NOWARN); + if (noncoherent) { + cma_obj->vaddr = dma_alloc_noncoherent(drm->dev, size, + &cma_obj->paddr, + DMA_TO_DEVICE, + GFP_KERNEL | __GFP_NOWARN); + + } else { + cma_obj->vaddr = dma_alloc_wc(drm->dev, size, &cma_obj->paddr, + GFP_KERNEL | __GFP_NOWARN); + } if (!cma_obj->vaddr) { drm_dbg(drm, "failed to allocate buffer with size %zu\n", size); @@ -130,6 +127,51 @@ struct drm_gem_cma_object *drm_gem_cma_create(struct drm_device *drm, drm_gem_object_put(&cma_obj->base); return ERR_PTR(ret); } + +/** + * drm_gem_cma_create_noncoherent - allocate an object with the given size + * and non-coherent cache attribute + * @drm: DRM device + * @size: size of the object to allocate + * + * This function creates a CMA GEM object and allocates a contiguous chunk of + * memory as backing store. The backing memory has the noncoherent attribute + * set. + * + * Creating non-coherent CMA objects is useful on architectures where writing + * to a buffer with the non-coherent cache attribute set then invalidating the + * cache is faster than writing to the same buffer with the write-combine cache + * attribute set. This is the case for instance on some Ingenic SoCs. + * + * Returns: + * A struct drm_gem_cma_object * on success or an ERR_PTR()-encoded negative + * error code on failure. + */ +struct drm_gem_cma_object * +drm_gem_cma_create_noncoherent(struct drm_device *drm, size_t size) +{ + return drm_gem_cma_create_with_cache_param(drm, size, true); +} +EXPORT_SYMBOL_GPL(drm_gem_cma_create_noncoherent); + +/** + * drm_gem_cma_create - allocate an object with the given size + * @drm: DRM device + * @size: size of the object to allocate + * + * This function creates a CMA GEM object and allocates a contiguous chunk of + * memory as backing store. The backing memory has the writecombine attribute + * set. + * + * Returns: + * A struct drm_gem_cma_object * on success or an ERR_PTR()-encoded negative + * error code on failure. + */ +struct drm_gem_cma_object *drm_gem_cma_create(struct drm_device *drm, + size_t size) +{ + return drm_gem_cma_create_with_cache_param(drm, size, false); +} EXPORT_SYMBOL_GPL(drm_gem_cma_create);
/** diff --git a/include/drm/drm_gem_cma_helper.h b/include/drm/drm_gem_cma_helper.h index 0a9711caa3e8..360771f5f485 100644 --- a/include/drm/drm_gem_cma_helper.h +++ b/include/drm/drm_gem_cma_helper.h @@ -79,6 +79,8 @@ int drm_gem_cma_dumb_create(struct drm_file *file_priv, /* allocate physical memory */ struct drm_gem_cma_object *drm_gem_cma_create(struct drm_device *drm, size_t size); +struct drm_gem_cma_object * +drm_gem_cma_create_noncoherent(struct drm_device *drm, size_t size);
extern const struct vm_operations_struct drm_gem_cma_vm_ops;