> -----Original Message-----
> From: Prathyush K [mailto:prathyus...@samsung.com]
> Sent: Wednesday, July 11, 2012 6:40 PM
> To: dri-devel@lists.freedesktop.org
> Cc: prathy...@chromium.org; m.szyprow...@samsung.com;
inki....@samsung.com;
> subash.ramasw...@linaro.org
> Subject: [PATCH 7/7] drm/exynos: Add IOMMU support for mapping gem object
>
> A gem object is created using dma_alloc_writecombine. Currently, this
> buffer is assumed to be contiguous. If a IOMMU mapping is created for
> DRM, this buffer would be non-contig so the map functions are modified
> to call dma_mmap_writecombine. This works for both contig and non-contig
> buffers.
>
> Signed-off-by: Prathyush K <prathyus...@samsung.com>
> ---
> drivers/gpu/drm/exynos/exynos_drm_gem.c | 35
++++++++++++++-------------
> ---
> 1 files changed, 16 insertions(+), 19 deletions(-)
>
> diff --git a/drivers/gpu/drm/exynos/exynos_drm_gem.c
> b/drivers/gpu/drm/exynos/exynos_drm_gem.c
> index 5c8b683..59240f7 100644
> --- a/drivers/gpu/drm/exynos/exynos_drm_gem.c
> +++ b/drivers/gpu/drm/exynos/exynos_drm_gem.c
> @@ -162,17 +162,22 @@ static int exynos_drm_gem_map_pages(struct
> drm_gem_object *obj,
> {
> struct exynos_drm_gem_obj *exynos_gem_obj = to_exynos_gem_obj(obj);
> struct exynos_drm_gem_buf *buf = exynos_gem_obj->buffer;
> - unsigned long pfn;
>
> if (exynos_gem_obj->flags & EXYNOS_BO_NONCONTIG) {
> + unsigned long pfn;
> if (!buf->pages)
> return -EINTR;
>
> pfn = page_to_pfn(buf->pages[page_offset++]);
> - } else
> - pfn = (buf->dma_addr >> PAGE_SHIFT) + page_offset;
> -
> - return vm_insert_mixed(vma, f_vaddr, pfn);
> + return vm_insert_mixed(vma, f_vaddr, pfn);
> + } else {
It's not good. EXYNOS_BO_NONCONTIG means physically non-contiguous otherwise
physically contiguous memory but with your patch, in case of using iommu,
memory type of the gem object may have no any meaning. in this case, the
memory type is EXYNOS_BO_CONTIG and has physically non-contiguous memory.
> + int ret;
> + ret = dma_mmap_writecombine(obj->dev->dev, vma, buf->kvaddr,
> + buf->dma_addr, buf->size);
> + if (ret)
> + DRM_ERROR("dma_mmap_writecombine failed\n");
> + return ret;
> + }
> }
>
> static int exynos_drm_gem_get_pages(struct drm_gem_object *obj)
> @@ -503,7 +508,7 @@ static int exynos_drm_gem_mmap_buffer(struct file
> *filp,
> struct drm_gem_object *obj = filp->private_data;
> struct exynos_drm_gem_obj *exynos_gem_obj = to_exynos_gem_obj(obj);
> struct exynos_drm_gem_buf *buffer;
> - unsigned long pfn, vm_size, usize, uaddr = vma->vm_start;
> + unsigned long vm_size, usize, uaddr = vma->vm_start;
> int ret;
>
> DRM_DEBUG_KMS("%s\n", __FILE__);
> @@ -543,19 +548,11 @@ static int exynos_drm_gem_mmap_buffer(struct file
> *filp,
> usize -= PAGE_SIZE;
> } while (usize > 0);
> } else {
> - /*
> - * get page frame number to physical memory to be mapped
> - * to user space.
> - */
> - pfn = ((unsigned long)exynos_gem_obj->buffer->dma_addr) >>
> - PAGE_SHIFT;
> -
> - DRM_DEBUG_KMS("pfn = 0x%lx\n", pfn);
> -
> - if (remap_pfn_range(vma, vma->vm_start, pfn, vm_size,
> - vma->vm_page_prot)) {
> - DRM_ERROR("failed to remap pfn range.\n");
> - return -EAGAIN;
> + ret = dma_mmap_writecombine(obj->dev->dev, vma, buffer-
> >kvaddr,
What if we don't use iommu and memory type of this buffer is non-contiguous?
> + buffer->dma_addr, buffer->size);
> + if (ret) {
> + DRM_ERROR("dma_mmap_writecombine failed\n");
> + return ret;
> }
> }
>
> --
> 1.7.0.4
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