Hello Thomasz, Laurent, I found an issue in the function vb2_dc_pages_to_sgt() below. I saw that during the attach, the size of the SGT and size requested mis-matched (by atleast 8k bytes). Hence I made a small correction to the code as below. I could then attach the importer properly.
Regards, Subash On 04/20/2012 08:15 PM, Tomasz Stanislawski wrote: > From: Andrzej Pietrasiewicz<andrzej.p at samsung.com> > > This patch introduces usage of dma_map_sg to map memory behind > a userspace pointer to a device as dma-contiguous mapping. > > Signed-off-by: Andrzej Pietrasiewicz<andrzej.p at samsung.com> > Signed-off-by: Marek Szyprowski<m.szyprowski at samsung.com> > [bugfixing] > Signed-off-by: Kamil Debski<k.debski at samsung.com> > [bugfixing] > Signed-off-by: Tomasz Stanislawski<t.stanislaws at samsung.com> > [add sglist subroutines/code refactoring] > Signed-off-by: Kyungmin Park<kyungmin.park at samsung.com> > --- > drivers/media/video/videobuf2-dma-contig.c | 279 > ++++++++++++++++++++++++++-- > 1 files changed, 262 insertions(+), 17 deletions(-) > > diff --git a/drivers/media/video/videobuf2-dma-contig.c > b/drivers/media/video/videobuf2-dma-contig.c > index 476e536..9cbc8d4 100644 > --- a/drivers/media/video/videobuf2-dma-contig.c > +++ b/drivers/media/video/videobuf2-dma-contig.c > @@ -11,6 +11,8 @@ > */ > > #include<linux/module.h> > +#include<linux/scatterlist.h> > +#include<linux/sched.h> > #include<linux/slab.h> > #include<linux/dma-mapping.h> > > @@ -22,6 +24,8 @@ struct vb2_dc_buf { > void *vaddr; > unsigned long size; > dma_addr_t dma_addr; > + enum dma_data_direction dma_dir; > + struct sg_table *dma_sgt; > > /* MMAP related */ > struct vb2_vmarea_handler handler; > @@ -32,6 +36,95 @@ struct vb2_dc_buf { > }; > > /*********************************************/ > +/* scatterlist table functions */ > +/*********************************************/ > + > +static struct sg_table *vb2_dc_pages_to_sgt(struct page **pages, > + unsigned int n_pages, unsigned long offset, unsigned long size) > +{ > + struct sg_table *sgt; > + unsigned int chunks; > + unsigned int i; > + unsigned int cur_page; > + int ret; > + struct scatterlist *s; > + > + sgt = kzalloc(sizeof *sgt, GFP_KERNEL); > + if (!sgt) > + return ERR_PTR(-ENOMEM); > + > + /* compute number of chunks */ > + chunks = 1; > + for (i = 1; i< n_pages; ++i) > + if (pages[i] != pages[i - 1] + 1) > + ++chunks; > + > + ret = sg_alloc_table(sgt, chunks, GFP_KERNEL); > + if (ret) { > + kfree(sgt); > + return ERR_PTR(-ENOMEM); > + } > + > + /* merging chunks and putting them into the scatterlist */ > + cur_page = 0; > + for_each_sg(sgt->sgl, s, sgt->orig_nents, i) { > + unsigned long chunk_size; > + unsigned int j; size = PAGE_SIZE; > + > + for (j = cur_page + 1; j< n_pages; ++j) for (j = cur_page + 1; j < n_pages; ++j) { > + if (pages[j] != pages[j - 1] + 1) > + break; size += PAGE } > + > + chunk_size = ((j - cur_page)<< PAGE_SHIFT) - offset; > + sg_set_page(s, pages[cur_page], min(size, chunk_size), offset); [DELETE] size -= chunk_size; > + offset = 0; > + cur_page = j; > + } > + > + return sgt; > +} > + > +static void vb2_dc_release_sgtable(struct sg_table *sgt) > +{ > + sg_free_table(sgt); > + kfree(sgt); > +} > + > +static void vb2_dc_sgt_foreach_page(struct sg_table *sgt, > + void (*cb)(struct page *pg)) > +{ > + struct scatterlist *s; > + unsigned int i; > + > + for_each_sg(sgt->sgl, s, sgt->nents, i) { > + struct page *page = sg_page(s); > + unsigned int n_pages = PAGE_ALIGN(s->offset + s->length) > + >> PAGE_SHIFT; > + unsigned int j; > + > + for (j = 0; j< n_pages; ++j, ++page) > + cb(page); > + } > +} > + > +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 */ > /*********************************************/ > > @@ -116,42 +209,194 @@ static int vb2_dc_mmap(void *buf_priv, struct > vm_area_struct *vma) > /* callbacks for USERPTR buffers */ > /*********************************************/ > > +static inline int vma_is_io(struct vm_area_struct *vma) > +{ > + return !!(vma->vm_flags& (VM_IO | VM_PFNMAP)); > +} > + > +static struct vm_area_struct *vb2_dc_get_user_vma( > + unsigned long start, unsigned long size) > +{ > + struct vm_area_struct *vma; > + > + /* current->mm->mmap_sem is taken by videobuf2 core */ > + vma = find_vma(current->mm, start); > + if (!vma) { > + printk(KERN_ERR "no vma for address %lu\n", start); > + return ERR_PTR(-EFAULT); > + } > + > + if (vma->vm_end - vma->vm_start< size) { > + printk(KERN_ERR "vma at %lu is too small for %lu bytes\n", > + start, size); > + return ERR_PTR(-EFAULT); > + } > + > + vma = vb2_get_vma(vma); > + if (!vma) { > + printk(KERN_ERR "failed to copy vma\n"); > + return ERR_PTR(-ENOMEM); > + } > + > + return vma; > +} > + > +static int vb2_dc_get_user_pages(unsigned long start, struct page **pages, > + int n_pages, struct vm_area_struct *vma, int write) > +{ > + if (vma_is_io(vma)) { > + unsigned int i; > + > + for (i = 0; i< n_pages; ++i, start += PAGE_SIZE) { > + unsigned long pfn; > + int ret = follow_pfn(vma, start,&pfn); > + > + if (ret) { > + printk(KERN_ERR "no page for address %lu\n", > + start); > + return ret; > + } > + pages[i] = pfn_to_page(pfn); > + } > + } else { > + unsigned int n; > + > + n = get_user_pages(current, current->mm, start& PAGE_MASK, > + n_pages, write, 1, pages, NULL); > + if (n != n_pages) { > + printk(KERN_ERR "got only %d of %d user pages\n", > + n, n_pages); > + while (n) > + put_page(pages[--n]); > + return -EFAULT; > + } > + } > + > + return 0; > +} > + > +static void vb2_dc_put_dirty_page(struct page *page) > +{ > + set_page_dirty_lock(page); > + put_page(page); > +} > + > +static void vb2_dc_put_userptr(void *buf_priv) > +{ > + struct vb2_dc_buf *buf = buf_priv; > + struct sg_table *sgt = buf->dma_sgt; > + > + dma_unmap_sg(buf->dev, sgt->sgl, sgt->orig_nents, buf->dma_dir); > + if (!vma_is_io(buf->vma)) > + vb2_dc_sgt_foreach_page(sgt, vb2_dc_put_dirty_page); > + > + vb2_dc_release_sgtable(sgt); > + vb2_put_vma(buf->vma); > + kfree(buf); > +} > + > static void *vb2_dc_get_userptr(void *alloc_ctx, unsigned long vaddr, > - unsigned long size, int write) > + unsigned long size, int write) > { > struct vb2_dc_buf *buf; > - struct vm_area_struct *vma; > - dma_addr_t dma_addr = 0; > - int ret; > + unsigned long start; > + unsigned long end; > + unsigned long offset; > + struct page **pages; > + int n_pages; > + int ret = 0; > + struct sg_table *sgt; > + unsigned long contig_size; > > buf = kzalloc(sizeof *buf, GFP_KERNEL); > if (!buf) > return ERR_PTR(-ENOMEM); > > - ret = vb2_get_contig_userptr(vaddr, size,&vma,&dma_addr); > + buf->dev = alloc_ctx; > + buf->dma_dir = write ? DMA_FROM_DEVICE : DMA_TO_DEVICE; > + > + start = vaddr& PAGE_MASK; > + offset = vaddr& ~PAGE_MASK; > + end = PAGE_ALIGN(vaddr + size); > + n_pages = (end - start)>> PAGE_SHIFT; > + > + pages = kmalloc(n_pages * sizeof pages[0], GFP_KERNEL); > + if (!pages) { > + ret = -ENOMEM; > + printk(KERN_ERR "failed to allocate pages table\n"); > + goto fail_buf; > + } > + > + buf->vma = vb2_dc_get_user_vma(start, size); > + if (IS_ERR(buf->vma)) { > + printk(KERN_ERR "failed to get VMA\n"); > + ret = PTR_ERR(buf->vma); > + goto fail_pages; > + } > + > + /* extract page list from userspace mapping */ > + ret = vb2_dc_get_user_pages(start, pages, n_pages, buf->vma, write); > if (ret) { > - printk(KERN_ERR "Failed acquiring VMA for vaddr 0x%08lx\n", > - vaddr); > - kfree(buf); > - return ERR_PTR(ret); > + printk(KERN_ERR "failed to get user pages\n"); > + goto fail_vma; > + } > + > + sgt = vb2_dc_pages_to_sgt(pages, n_pages, offset, size); > + if (IS_ERR(sgt)) { > + printk(KERN_ERR "failed to create scatterlist table\n"); > + ret = -ENOMEM; > + goto fail_get_user_pages; > + } > + > + /* pages are no longer needed */ > + kfree(pages); > + pages = NULL; > + > + sgt->nents = dma_map_sg(buf->dev, sgt->sgl, sgt->orig_nents, > + buf->dma_dir); > + if (sgt->nents<= 0) { > + printk(KERN_ERR "failed to map scatterlist\n"); > + ret = -EIO; > + goto fail_sgt; > } > > + contig_size = vb2_dc_get_contiguous_size(sgt); > + if (contig_size< size) { > + printk(KERN_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->size = size; > - buf->dma_addr = dma_addr; > - buf->vma = vma; > + buf->dma_sgt = sgt; > > return buf; > -} > > -static void vb2_dc_put_userptr(void *mem_priv) > -{ > - struct vb2_dc_buf *buf = mem_priv; > +fail_map_sg: > + dma_unmap_sg(buf->dev, sgt->sgl, sgt->nents, buf->dma_dir); > > - if (!buf) > - return; > +fail_sgt: > + if (!vma_is_io(buf->vma)) > + vb2_dc_sgt_foreach_page(sgt, put_page); > + vb2_dc_release_sgtable(sgt); > + > +fail_get_user_pages: > + if (pages&& !vma_is_io(buf->vma)) > + while (n_pages) > + put_page(pages[--n_pages]); > > +fail_vma: > vb2_put_vma(buf->vma); > + > +fail_pages: > + kfree(pages); /* kfree is NULL-proof */ > + > +fail_buf: > kfree(buf); > + > + return ERR_PTR(ret); > } > > /*********************************************/