On 2015년 02월 04일 18:23, Carlo Caione wrote:
> The Exynos DRM driver doesn't follow the correct API when dealing with
> dma_{alloc, mmap, free}_attrs functions and the
> DMA_ATTR_NO_KERNEL_MAPPING attribute.
>
> When a IOMMU is not available and the DMA_ATTR_NO_KERNEL_MAPPING is
> used, the driver should use the pointer returned by dma_alloc_attr() as
> a cookie.
>
> The Exynos DRM driver directly uses the non-requested virtual kernel
> address returned by the DMA mapping subsystem. This just works now
> because the non-IOMMU codepath doesn't obey DMA_ATTR_NO_KERNEL_MAPPING
> but we need to fix it before fixing the DMA layer.
Applied.
Thanks,
Inki Dae
>
> Signed-off-by: Carlo Caione <carlo@xxxxxxxxxx>
> Acked-by: Joonyoung Shim <jy0922.shim@xxxxxxxxxxx>
> ---
> drivers/gpu/drm/exynos/exynos_drm_buf.c | 6 +++---
> drivers/gpu/drm/exynos/exynos_drm_fbdev.c | 29 +++++++++--------------------
> drivers/gpu/drm/exynos/exynos_drm_gem.h | 2 ++
> 3 files changed, 14 insertions(+), 23 deletions(-)
>
> diff --git a/drivers/gpu/drm/exynos/exynos_drm_buf.c b/drivers/gpu/drm/exynos/exynos_drm_buf.c
> index 9c80884..24994ba 100644
> --- a/drivers/gpu/drm/exynos/exynos_drm_buf.c
> +++ b/drivers/gpu/drm/exynos/exynos_drm_buf.c
> @@ -63,11 +63,11 @@ static int lowlevel_buffer_allocate(struct drm_device *dev,
> return -ENOMEM;
> }
>
> - buf->kvaddr = (void __iomem *)dma_alloc_attrs(dev->dev,
> + buf->cookie = dma_alloc_attrs(dev->dev,
> buf->size,
> &buf->dma_addr, GFP_KERNEL,
> &buf->dma_attrs);
> - if (!buf->kvaddr) {
> + if (!buf->cookie) {
> DRM_ERROR("failed to allocate buffer.\n");
> ret = -ENOMEM;
> goto err_free;
> @@ -132,7 +132,7 @@ static void lowlevel_buffer_deallocate(struct drm_device *dev,
> buf->sgt = NULL;
>
> if (!is_drm_iommu_supported(dev)) {
> - dma_free_attrs(dev->dev, buf->size, buf->kvaddr,
> + dma_free_attrs(dev->dev, buf->size, buf->cookie,
> (dma_addr_t)buf->dma_addr, &buf->dma_attrs);
> drm_free_large(buf->pages);
> } else
> diff --git a/drivers/gpu/drm/exynos/exynos_drm_fbdev.c b/drivers/gpu/drm/exynos/exynos_drm_fbdev.c
> index e12ea90..84f8dfe 100644
> --- a/drivers/gpu/drm/exynos/exynos_drm_fbdev.c
> +++ b/drivers/gpu/drm/exynos/exynos_drm_fbdev.c
> @@ -79,9 +79,9 @@ static int exynos_drm_fbdev_update(struct drm_fb_helper *helper,
> struct drm_framebuffer *fb)
> {
> struct fb_info *fbi = helper->fbdev;
> - struct drm_device *dev = helper->dev;
> struct exynos_drm_gem_buf *buffer;
> unsigned int size = fb->width * fb->height * (fb->bits_per_pixel >> 3);
> + unsigned int nr_pages;
> unsigned long offset;
>
> drm_fb_helper_fill_fix(fbi, fb->pitches[0], fb->depth);
> @@ -94,25 +94,14 @@ static int exynos_drm_fbdev_update(struct drm_fb_helper *helper,
> return -EFAULT;
> }
>
> - /* map pages with kernel virtual space. */
> + nr_pages = buffer->size >> PAGE_SHIFT;
> +
> + buffer->kvaddr = (void __iomem *) vmap(buffer->pages,
> + nr_pages, VM_MAP,
> + pgprot_writecombine(PAGE_KERNEL));
> if (!buffer->kvaddr) {
> - if (is_drm_iommu_supported(dev)) {
> - unsigned int nr_pages = buffer->size >> PAGE_SHIFT;
> -
> - buffer->kvaddr = (void __iomem *) vmap(buffer->pages,
> - nr_pages, VM_MAP,
> - pgprot_writecombine(PAGE_KERNEL));
> - } else {
> - phys_addr_t dma_addr = buffer->dma_addr;
> - if (dma_addr)
> - buffer->kvaddr = (void __iomem *)phys_to_virt(dma_addr);
> - else
> - buffer->kvaddr = (void __iomem *)NULL;
> - }
> - if (!buffer->kvaddr) {
> - DRM_ERROR("failed to map pages to kernel space.\n");
> - return -EIO;
> - }
> + DRM_ERROR("failed to map pages to kernel space.\n");
> + return -EIO;
> }
>
> /* buffer count to framebuffer always is 1 at booting time. */
> @@ -313,7 +302,7 @@ static void exynos_drm_fbdev_destroy(struct drm_device *dev,
> struct exynos_drm_gem_obj *exynos_gem_obj = exynos_fbd->exynos_gem_obj;
> struct drm_framebuffer *fb;
>
> - if (is_drm_iommu_supported(dev) && exynos_gem_obj->buffer->kvaddr)
> + if (exynos_gem_obj->buffer->kvaddr)
> vunmap(exynos_gem_obj->buffer->kvaddr);
>
> /* release drm framebuffer and real buffer */
> diff --git a/drivers/gpu/drm/exynos/exynos_drm_gem.h b/drivers/gpu/drm/exynos/exynos_drm_gem.h
> index ec58fe9..308173c 100644
> --- a/drivers/gpu/drm/exynos/exynos_drm_gem.h
> +++ b/drivers/gpu/drm/exynos/exynos_drm_gem.h
> @@ -22,6 +22,7 @@
> /*
> * exynos drm gem buffer structure.
> *
> + * @cookie: cookie returned by dma_alloc_attrs
> * @kvaddr: kernel virtual address to allocated memory region.
> * *userptr: user space address.
> * @dma_addr: bus address(accessed by dma) to allocated memory region.
> @@ -35,6 +36,7 @@
> * VM_PFNMAP or not.
> */
> struct exynos_drm_gem_buf {
> + void *cookie;
> void __iomem *kvaddr;
> unsigned long userptr;
> dma_addr_t dma_addr;
>
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