diff options
Diffstat (limited to 'drivers/media/common/videobuf2/videobuf2-dma-contig.c')
| -rw-r--r-- | drivers/media/common/videobuf2/videobuf2-dma-contig.c | 787 |
1 files changed, 787 insertions, 0 deletions
diff --git a/drivers/media/common/videobuf2/videobuf2-dma-contig.c b/drivers/media/common/videobuf2/videobuf2-dma-contig.c new file mode 100644 index 000000000000..f1178f6f434d --- /dev/null +++ b/drivers/media/common/videobuf2/videobuf2-dma-contig.c @@ -0,0 +1,787 @@ +/* + * videobuf2-dma-contig.c - DMA contig memory allocator for videobuf2 + * + * Copyright (C) 2010 Samsung Electronics + * + * Author: Pawel Osciak <pawel@osciak.com> + * + * This program is free software; you can redistribute it and/or modify + * it under the terms of the GNU General Public License as published by + * the Free Software Foundation. + */ + +#include <linux/dma-buf.h> +#include <linux/module.h> +#include <linux/refcount.h> +#include <linux/scatterlist.h> +#include <linux/sched.h> +#include <linux/slab.h> +#include <linux/dma-mapping.h> + +#include <media/videobuf2-v4l2.h> +#include <media/videobuf2-dma-contig.h> +#include <media/videobuf2-memops.h> + +struct vb2_dc_buf { + struct device *dev; + void *vaddr; + unsigned long size; + void *cookie; + dma_addr_t dma_addr; + unsigned long attrs; + enum dma_data_direction dma_dir; + struct sg_table *dma_sgt; + struct frame_vector *vec; + + /* MMAP related */ + struct vb2_vmarea_handler handler; + refcount_t refcount; + struct sg_table *sgt_base; + + /* DMABUF related */ + struct dma_buf_attachment *db_attach; +}; + +/*********************************************/ +/* scatterlist table functions */ +/*********************************************/ + +static unsigned long vb2_dc_get_contiguous_size(struct sg_table *sgt) +{ + struct scatterlist *s; + dma_addr_t expected = sg_dma_address(sgt->sgl); + unsigned int i; + unsigned long size = 0; + + for_each_sg(sgt->sgl, s, sgt->nents, i) { + if (sg_dma_address(s) != expected) + break; + expected = sg_dma_address(s) + sg_dma_len(s); + size += sg_dma_len(s); + } + return size; +} + +/*********************************************/ +/* callbacks for all buffers */ +/*********************************************/ + +static void *vb2_dc_cookie(void *buf_priv) +{ + struct vb2_dc_buf *buf = buf_priv; + + return &buf->dma_addr; +} + +static void *vb2_dc_vaddr(void *buf_priv) +{ + struct vb2_dc_buf *buf = buf_priv; + + if (!buf->vaddr && buf->db_attach) + buf->vaddr = dma_buf_vmap(buf->db_attach->dmabuf); + + return buf->vaddr; +} + +static unsigned int vb2_dc_num_users(void *buf_priv) +{ + struct vb2_dc_buf *buf = buf_priv; + + return refcount_read(&buf->refcount); +} + +static void vb2_dc_prepare(void *buf_priv) +{ + struct vb2_dc_buf *buf = buf_priv; + struct sg_table *sgt = buf->dma_sgt; + + /* DMABUF exporter will flush the cache for us */ + if (!sgt || buf->db_attach) + return; + + dma_sync_sg_for_device(buf->dev, sgt->sgl, sgt->orig_nents, + buf->dma_dir); +} + +static void vb2_dc_finish(void *buf_priv) +{ + struct vb2_dc_buf *buf = buf_priv; + struct sg_table *sgt = buf->dma_sgt; + + /* DMABUF exporter will flush the cache for us */ + if (!sgt || buf->db_attach) + return; + + dma_sync_sg_for_cpu(buf->dev, sgt->sgl, sgt->orig_nents, buf->dma_dir); +} + +/*********************************************/ +/* callbacks for MMAP buffers */ +/*********************************************/ + +static void vb2_dc_put(void *buf_priv) +{ + struct vb2_dc_buf *buf = buf_priv; + + if (!refcount_dec_and_test(&buf->refcount)) + return; + + if (buf->sgt_base) { + sg_free_table(buf->sgt_base); + kfree(buf->sgt_base); + } + dma_free_attrs(buf->dev, buf->size, buf->cookie, buf->dma_addr, + buf->attrs); + put_device(buf->dev); + kfree(buf); +} + +static void *vb2_dc_alloc(struct device *dev, unsigned long attrs, + unsigned long size, enum dma_data_direction dma_dir, + gfp_t gfp_flags) +{ + struct vb2_dc_buf *buf; + + if (WARN_ON(!dev)) + return ERR_PTR(-EINVAL); + + buf = kzalloc(sizeof *buf, GFP_KERNEL); + if (!buf) + return ERR_PTR(-ENOMEM); + + if (attrs) + buf->attrs = attrs; + buf->cookie = dma_alloc_attrs(dev, size, &buf->dma_addr, + GFP_KERNEL | gfp_flags, buf->attrs); + if (!buf->cookie) { + dev_err(dev, "dma_alloc_coherent of size %ld failed\n", size); + kfree(buf); + return ERR_PTR(-ENOMEM); + } + + if ((buf->attrs & DMA_ATTR_NO_KERNEL_MAPPING) == 0) + buf->vaddr = buf->cookie; + + /* Prevent the device from being released while the buffer is used */ + buf->dev = get_device(dev); + buf->size = size; + buf->dma_dir = dma_dir; + + buf->handler.refcount = &buf->refcount; + buf->handler.put = vb2_dc_put; + buf->handler.arg = buf; + + refcount_set(&buf->refcount, 1); + + return buf; +} + +static int vb2_dc_mmap(void *buf_priv, struct vm_area_struct *vma) +{ + struct vb2_dc_buf *buf = buf_priv; + int ret; + + if (!buf) { + printk(KERN_ERR "No buffer to map\n"); + return -EINVAL; + } + + /* + * dma_mmap_* uses vm_pgoff as in-buffer offset, but we want to + * map whole buffer + */ + vma->vm_pgoff = 0; + + ret = dma_mmap_attrs(buf->dev, vma, buf->cookie, + buf->dma_addr, buf->size, buf->attrs); + + if (ret) { + pr_err("Remapping memory failed, error: %d\n", ret); + return ret; + } + + vma->vm_flags |= VM_DONTEXPAND | VM_DONTDUMP; + vma->vm_private_data = &buf->handler; + vma->vm_ops = &vb2_common_vm_ops; + + vma->vm_ops->open(vma); + + pr_debug("%s: mapped dma addr 0x%08lx at 0x%08lx, size %ld\n", + __func__, (unsigned long)buf->dma_addr, vma->vm_start, + buf->size); + + return 0; +} + +/*********************************************/ +/* DMABUF ops for exporters */ +/*********************************************/ + +struct vb2_dc_attachment { + struct sg_table sgt; + enum dma_data_direction dma_dir; +}; + +static int vb2_dc_dmabuf_ops_attach(struct dma_buf *dbuf, struct device *dev, + struct dma_buf_attachment *dbuf_attach) +{ + struct vb2_dc_attachment *attach; + unsigned int i; + struct scatterlist *rd, *wr; + struct sg_table *sgt; + struct vb2_dc_buf *buf = dbuf->priv; + int ret; + + attach = kzalloc(sizeof(*attach), GFP_KERNEL); + if (!attach) + return -ENOMEM; + + sgt = &attach->sgt; + /* Copy the buf->base_sgt scatter list to the attachment, as we can't + * map the same scatter list to multiple attachments at the same time. + */ + ret = sg_alloc_table(sgt, buf->sgt_base->orig_nents, GFP_KERNEL); + if (ret) { + kfree(attach); + return -ENOMEM; + } + + rd = buf->sgt_base->sgl; + wr = sgt->sgl; + for (i = 0; i < sgt->orig_nents; ++i) { + sg_set_page(wr, sg_page(rd), rd->length, rd->offset); + rd = sg_next(rd); + wr = sg_next(wr); + } + + attach->dma_dir = DMA_NONE; + dbuf_attach->priv = attach; + + return 0; +} + +static void vb2_dc_dmabuf_ops_detach(struct dma_buf *dbuf, + struct dma_buf_attachment *db_attach) +{ + struct vb2_dc_attachment *attach = db_attach->priv; + struct sg_table *sgt; + + if (!attach) + return; + + sgt = &attach->sgt; + + /* release the scatterlist cache */ + if (attach->dma_dir != DMA_NONE) + dma_unmap_sg(db_attach->dev, sgt->sgl, sgt->orig_nents, + attach->dma_dir); + sg_free_table(sgt); + kfree(attach); + db_attach->priv = NULL; +} + +static struct sg_table *vb2_dc_dmabuf_ops_map( + struct dma_buf_attachment *db_attach, enum dma_data_direction dma_dir) +{ + struct vb2_dc_attachment *attach = db_attach->priv; + /* stealing dmabuf mutex to serialize map/unmap operations */ + struct mutex *lock = &db_attach->dmabuf->lock; + struct sg_table *sgt; + + mutex_lock(lock); + + sgt = &attach->sgt; + /* return previously mapped sg table */ + if (attach->dma_dir == dma_dir) { + mutex_unlock(lock); + return sgt; + } + + /* release any previous cache */ + if (attach->dma_dir != DMA_NONE) { + dma_unmap_sg(db_attach->dev, sgt->sgl, sgt->orig_nents, + attach->dma_dir); + attach->dma_dir = DMA_NONE; + } + + /* mapping to the client with new direction */ + sgt->nents = dma_map_sg(db_attach->dev, sgt->sgl, sgt->orig_nents, + dma_dir); + if (!sgt->nents) { + pr_err("failed to map scatterlist\n"); + mutex_unlock(lock); + return ERR_PTR(-EIO); + } + + attach->dma_dir = dma_dir; + + mutex_unlock(lock); + + return sgt; +} + +static void vb2_dc_dmabuf_ops_unmap(struct dma_buf_attachment *db_attach, + struct sg_table *sgt, enum dma_data_direction dma_dir) +{ + /* nothing to be done here */ +} + +static void vb2_dc_dmabuf_ops_release(struct dma_buf *dbuf) +{ + /* drop reference obtained in vb2_dc_get_dmabuf */ + vb2_dc_put(dbuf->priv); +} + +static void *vb2_dc_dmabuf_ops_kmap(struct dma_buf *dbuf, unsigned long pgnum) +{ + struct vb2_dc_buf *buf = dbuf->priv; + + return buf->vaddr ? buf->vaddr + pgnum * PAGE_SIZE : NULL; +} + +static void *vb2_dc_dmabuf_ops_vmap(struct dma_buf *dbuf) +{ + struct vb2_dc_buf *buf = dbuf->priv; + + return buf->vaddr; +} + +static int vb2_dc_dmabuf_ops_mmap(struct dma_buf *dbuf, + struct vm_area_struct *vma) +{ + return vb2_dc_mmap(dbuf->priv, vma); +} + +static const struct dma_buf_ops vb2_dc_dmabuf_ops = { + .attach = vb2_dc_dmabuf_ops_attach, + .detach = vb2_dc_dmabuf_ops_detach, + .map_dma_buf = vb2_dc_dmabuf_ops_map, + .unmap_dma_buf = vb2_dc_dmabuf_ops_unmap, + .map = vb2_dc_dmabuf_ops_kmap, + .map_atomic = vb2_dc_dmabuf_ops_kmap, + .vmap = vb2_dc_dmabuf_ops_vmap, + .mmap = vb2_dc_dmabuf_ops_mmap, + .release = vb2_dc_dmabuf_ops_release, +}; + +static struct sg_table *vb2_dc_get_base_sgt(struct vb2_dc_buf *buf) +{ + int ret; + struct sg_table *sgt; + + sgt = kmalloc(sizeof(*sgt), GFP_KERNEL); + if (!sgt) { + dev_err(buf->dev, "failed to alloc sg table\n"); + return NULL; + } + + ret = dma_get_sgtable_attrs(buf->dev, sgt, buf->cookie, buf->dma_addr, + buf->size, buf->attrs); + if (ret < 0) { + dev_err(buf->dev, "failed to get scatterlist from DMA API\n"); + kfree(sgt); + return NULL; + } + + return sgt; +} + +static struct dma_buf *vb2_dc_get_dmabuf(void *buf_priv, unsigned long flags) +{ + struct vb2_dc_buf *buf = buf_priv; + struct dma_buf *dbuf; + DEFINE_DMA_BUF_EXPORT_INFO(exp_info); + + exp_info.ops = &vb2_dc_dmabuf_ops; + exp_info.size = buf->size; + exp_info.flags = flags; + exp_info.priv = buf; + + if (!buf->sgt_base) + buf->sgt_base = vb2_dc_get_base_sgt(buf); + + if (WARN_ON(!buf->sgt_base)) + return NULL; + + dbuf = dma_buf_export(&exp_info); + if (IS_ERR(dbuf)) + return NULL; + + /* dmabuf keeps reference to vb2 buffer */ + refcount_inc(&buf->refcount); + + return dbuf; +} + +/*********************************************/ +/* callbacks for USERPTR buffers */ +/*********************************************/ + +static void vb2_dc_put_userptr(void *buf_priv) +{ + struct vb2_dc_buf *buf = buf_priv; + struct sg_table *sgt = buf->dma_sgt; + int i; + struct page **pages; + + if (sgt) { + /* + * No need to sync to CPU, it's already synced to the CPU + * since the finish() memop will have been called before this. + */ + dma_unmap_sg_attrs(buf->dev, sgt->sgl, sgt->orig_nents, + buf->dma_dir, DMA_ATTR_SKIP_CPU_SYNC); + pages = frame_vector_pages(buf->vec); + /* sgt should exist only if vector contains pages... */ + BUG_ON(IS_ERR(pages)); + if (buf->dma_dir == DMA_FROM_DEVICE || + buf->dma_dir == DMA_BIDIRECTIONAL) + for (i = 0; i < frame_vector_count(buf->vec); i++) + set_page_dirty_lock(pages[i]); + sg_free_table(sgt); + kfree(sgt); + } + vb2_destroy_framevec(buf->vec); + kfree(buf); +} + +/* + * For some kind of reserved memory there might be no struct page available, + * so all that can be done to support such 'pages' is to try to convert + * pfn to dma address or at the last resort just assume that + * dma address == physical address (like it has been assumed in earlier version + * of videobuf2-dma-contig + */ + +#ifdef __arch_pfn_to_dma +static inline dma_addr_t vb2_dc_pfn_to_dma(struct device *dev, unsigned long pfn) +{ + return (dma_addr_t)__arch_pfn_to_dma(dev, pfn); +} +#elif defined(__pfn_to_bus) +static inline dma_addr_t vb2_dc_pfn_to_dma(struct device *dev, unsigned long pfn) +{ + return (dma_addr_t)__pfn_to_bus(pfn); +} +#elif defined(__pfn_to_phys) +static inline dma_addr_t vb2_dc_pfn_to_dma(struct device *dev, unsigned long pfn) +{ + return (dma_addr_t)__pfn_to_phys(pfn); +} +#else +static inline dma_addr_t vb2_dc_pfn_to_dma(struct device *dev, unsigned long pfn) +{ + /* really, we cannot do anything better at this point */ + return (dma_addr_t)(pfn) << PAGE_SHIFT; +} +#endif + +static void *vb2_dc_get_userptr(struct device *dev, unsigned long vaddr, + unsigned long size, enum dma_data_direction dma_dir) +{ + struct vb2_dc_buf *buf; + struct frame_vector *vec; + unsigned int offset; + int n_pages, i; + int ret = 0; + struct sg_table *sgt; + unsigned long contig_size; + unsigned long dma_align = dma_get_cache_alignment(); + + /* Only cache aligned DMA transfers are reliable */ + if (!IS_ALIGNED(vaddr | size, dma_align)) { + pr_debug("user data must be aligned to %lu bytes\n", dma_align); + return ERR_PTR(-EINVAL); + } + + if (!size) { + pr_debug("size is zero\n"); + return ERR_PTR(-EINVAL); + } + + if (WARN_ON(!dev)) + return ERR_PTR(-EINVAL); + + buf = kzalloc(sizeof *buf, GFP_KERNEL); + if (!buf) + return ERR_PTR(-ENOMEM); + + buf->dev = dev; + buf->dma_dir = dma_dir; + + offset = lower_32_bits(offset_in_page(vaddr)); + vec = vb2_create_framevec(vaddr, size, dma_dir == DMA_FROM_DEVICE || + dma_dir == DMA_BIDIRECTIONAL); + if (IS_ERR(vec)) { + ret = PTR_ERR(vec); + goto fail_buf; + } + buf->vec = vec; + n_pages = frame_vector_count(vec); + ret = frame_vector_to_pages(vec); + if (ret < 0) { + unsigned long *nums = frame_vector_pfns(vec); + + /* + * Failed to convert to pages... Check the memory is physically + * contiguous and use direct mapping + */ + for (i = 1; i < n_pages; i++) + if (nums[i-1] + 1 != nums[i]) + goto fail_pfnvec; + buf->dma_addr = vb2_dc_pfn_to_dma(buf->dev, nums[0]); + goto out; + } + + sgt = kzalloc(sizeof(*sgt), GFP_KERNEL); + if (!sgt) { + pr_err("failed to allocate sg table\n"); + ret = -ENOMEM; + goto fail_pfnvec; + } + + ret = sg_alloc_table_from_pages(sgt, frame_vector_pages(vec), n_pages, + offset, size, GFP_KERNEL); + if (ret) { + pr_err("failed to initialize sg table\n"); + goto fail_sgt; + } + + /* + * No need to sync to the device, this will happen later when the + * prepare() memop is called. + */ + sgt->nents = dma_map_sg_attrs(buf->dev, sgt->sgl, sgt->orig_nents, + buf->dma_dir, DMA_ATTR_SKIP_CPU_SYNC); + if (sgt->nents <= 0) { + pr_err("failed to map scatterlist\n"); + ret = -EIO; + goto fail_sgt_init; + } + + contig_size = vb2_dc_get_contiguous_size(sgt); + if (contig_size < size) { + pr_err("contiguous mapping is too small %lu/%lu\n", + contig_size, size); + ret = -EFAULT; + goto fail_map_sg; + } + + buf->dma_addr = sg_dma_address(sgt->sgl); + buf->dma_sgt = sgt; +out: + buf->size = size; + + return buf; + +fail_map_sg: + dma_unmap_sg_attrs(buf->dev, sgt->sgl, sgt->orig_nents, + buf->dma_dir, DMA_ATTR_SKIP_CPU_SYNC); + +fail_sgt_init: + sg_free_table(sgt); + +fail_sgt: + kfree(sgt); + +fail_pfnvec: + vb2_destroy_framevec(vec); + +fail_buf: + kfree(buf); + + return ERR_PTR(ret); +} + +/*********************************************/ +/* callbacks for DMABUF buffers */ +/*********************************************/ + +static int vb2_dc_map_dmabuf(void *mem_priv) +{ + struct vb2_dc_buf *buf = mem_priv; + struct sg_table *sgt; + unsigned long contig_size; + + if (WARN_ON(!buf->db_attach)) { + pr_err("trying to pin a non attached buffer\n"); + return -EINVAL; + } + + if (WARN_ON(buf->dma_sgt)) { + pr_err("dmabuf buffer is already pinned\n"); + return 0; + } + + /* get the associated scatterlist for this buffer */ + sgt = dma_buf_map_attachment(buf->db_attach, buf->dma_dir); + if (IS_ERR(sgt)) { + pr_err("Error getting dmabuf scatterlist\n"); + return -EINVAL; + } + + /* checking if dmabuf is big enough to store contiguous chunk */ + contig_size = vb2_dc_get_contiguous_size(sgt); + if (contig_size < buf->size) { + pr_err("contiguous chunk is too small %lu/%lu b\n", + contig_size, buf->size); + dma_buf_unmap_attachment(buf->db_attach, sgt, buf->dma_dir); + return -EFAULT; + } + + buf->dma_addr = sg_dma_address(sgt->sgl); + buf->dma_sgt = sgt; + buf->vaddr = NULL; + + return 0; +} + +static void vb2_dc_unmap_dmabuf(void *mem_priv) +{ + struct vb2_dc_buf *buf = mem_priv; + struct sg_table *sgt = buf->dma_sgt; + + if (WARN_ON(!buf->db_attach)) { + pr_err("trying to unpin a not attached buffer\n"); + return; + } + + if (WARN_ON(!sgt)) { + pr_err("dmabuf buffer is already unpinned\n"); + return; + } + + if (buf->vaddr) { + dma_buf_vunmap(buf->db_attach->dmabuf, buf->vaddr); + buf->vaddr = NULL; + } + dma_buf_unmap_attachment(buf->db_attach, sgt, buf->dma_dir); + + buf->dma_addr = 0; + buf->dma_sgt = NULL; +} + +static void vb2_dc_detach_dmabuf(void *mem_priv) +{ + struct vb2_dc_buf *buf = mem_priv; + + /* if vb2 works correctly you should never detach mapped buffer */ + if (WARN_ON(buf->dma_addr)) + vb2_dc_unmap_dmabuf(buf); + + /* detach this attachment */ + dma_buf_detach(buf->db_attach->dmabuf, buf->db_attach); + kfree(buf); +} + +static void *vb2_dc_attach_dmabuf(struct device *dev, struct dma_buf *dbuf, + unsigned long size, enum dma_data_direction dma_dir) +{ + struct vb2_dc_buf *buf; + struct dma_buf_attachment *dba; + + if (dbuf->size < size) + return ERR_PTR(-EFAULT); + + if (WARN_ON(!dev)) + return ERR_PTR(-EINVAL); + + buf = kzalloc(sizeof(*buf), GFP_KERNEL); + if (!buf) + return ERR_PTR(-ENOMEM); + + buf->dev = dev; + /* create attachment for the dmabuf with the user device */ + dba = dma_buf_attach(dbuf, buf->dev); + if (IS_ERR(dba)) { + pr_err("failed to attach dmabuf\n"); + kfree(buf); + return dba; + } + + buf->dma_dir = dma_dir; + buf->size = size; + buf->db_attach = dba; + + return buf; +} + +/*********************************************/ +/* DMA CONTIG exported functions */ +/*********************************************/ + +const struct vb2_mem_ops vb2_dma_contig_memops = { + .alloc = vb2_dc_alloc, + .put = vb2_dc_put, + .get_dmabuf = vb2_dc_get_dmabuf, + .cookie = vb2_dc_cookie, + .vaddr = vb2_dc_vaddr, + .mmap = vb2_dc_mmap, + .get_userptr = vb2_dc_get_userptr, + .put_userptr = vb2_dc_put_userptr, + .prepare = vb2_dc_prepare, + .finish = vb2_dc_finish, + .map_dmabuf = vb2_dc_map_dmabuf, + .unmap_dmabuf = vb2_dc_unmap_dmabuf, + .attach_dmabuf = vb2_dc_attach_dmabuf, + .detach_dmabuf = vb2_dc_detach_dmabuf, + .num_users = vb2_dc_num_users, +}; +EXPORT_SYMBOL_GPL(vb2_dma_contig_memops); + +/** + * vb2_dma_contig_set_max_seg_size() - configure DMA max segment size + * @dev: device for configuring DMA parameters + * @size: size of DMA max segment size to set + * + * To allow mapping the scatter-list into a single chunk in the DMA + * address space, the device is required to have the DMA max segment + * size parameter set to a value larger than the buffer size. Otherwise, + * the DMA-mapping subsystem will split the mapping into max segment + * size chunks. This function sets the DMA max segment size + * parameter to let DMA-mapping map a buffer as a single chunk in DMA + * address space. + * This code assumes that the DMA-mapping subsystem will merge all + * scatterlist segments if this is really possible (for example when + * an IOMMU is available and enabled). + * Ideally, this parameter should be set by the generic bus code, but it + * is left with the default 64KiB value due to historical litmiations in + * other subsystems (like limited USB host drivers) and there no good + * place to set it to the proper value. + * This function should be called from the drivers, which are known to + * operate on platforms with IOMMU and provide access to shared buffers + * (either USERPTR or DMABUF). This should be done before initializing + * videobuf2 queue. + */ +int vb2_dma_contig_set_max_seg_size(struct device *dev, unsigned int size) +{ + if (!dev->dma_parms) { + dev->dma_parms = kzalloc(sizeof(*dev->dma_parms), GFP_KERNEL); + if (!dev->dma_parms) + return -ENOMEM; + } + if (dma_get_max_seg_size(dev) < size) + return dma_set_max_seg_size(dev, size); + + return 0; +} +EXPORT_SYMBOL_GPL(vb2_dma_contig_set_max_seg_size); + +/* + * vb2_dma_contig_clear_max_seg_size() - release resources for DMA parameters + * @dev: device for configuring DMA parameters + * + * This function releases resources allocated to configure DMA parameters + * (see vb2_dma_contig_set_max_seg_size() function). It should be called from + * device drivers on driver remove. + */ +void vb2_dma_contig_clear_max_seg_size(struct device *dev) +{ + kfree(dev->dma_parms); + dev->dma_parms = NULL; +} +EXPORT_SYMBOL_GPL(vb2_dma_contig_clear_max_seg_size); + +MODULE_DESCRIPTION("DMA-contig memory handling routines for videobuf2"); +MODULE_AUTHOR("Pawel Osciak <pawel@osciak.com>"); +MODULE_LICENSE("GPL"); |