20. 4. 7. 오후 10:42에 Marek Szyprowski 이(가) 쓴 글:
> Internal pages array and scatter-list for them is not really needed for
> anything. FBDev emulation can simply rely on the DMA-mapping framework
> to create a proper kernel mapping for the buffer, while all other buffer
> use cases don't really need that array at all.

Picked it up.

Thanks,
Inki Dae

> 
> Suggested-by: Christian König <christian.koe...@amd.com>
> Signed-off-by: Marek Szyprowski <m.szyprow...@samsung.com>
> ---
>  drivers/gpu/drm/exynos/exynos_drm_fbdev.c |  28 +----
>  drivers/gpu/drm/exynos/exynos_drm_gem.c   | 124 +++++++---------------
>  drivers/gpu/drm/exynos/exynos_drm_gem.h   |  13 +--
>  3 files changed, 42 insertions(+), 123 deletions(-)
> 
> diff --git a/drivers/gpu/drm/exynos/exynos_drm_fbdev.c 
> b/drivers/gpu/drm/exynos/exynos_drm_fbdev.c
> index e6ceaf36fb04..56a2b47e1af7 100644
> --- a/drivers/gpu/drm/exynos/exynos_drm_fbdev.c
> +++ b/drivers/gpu/drm/exynos/exynos_drm_fbdev.c
> @@ -76,7 +76,6 @@ static int exynos_drm_fbdev_update(struct drm_fb_helper 
> *helper,
>       struct fb_info *fbi;
>       struct drm_framebuffer *fb = helper->fb;
>       unsigned int size = fb->width * fb->height * fb->format->cpp[0];
> -     unsigned int nr_pages;
>       unsigned long offset;
>  
>       fbi = drm_fb_helper_alloc_fbi(helper);
> @@ -90,16 +89,6 @@ static int exynos_drm_fbdev_update(struct drm_fb_helper 
> *helper,
>  
>       drm_fb_helper_fill_info(fbi, helper, sizes);
>  
> -     nr_pages = exynos_gem->size >> PAGE_SHIFT;
> -
> -     exynos_gem->kvaddr = (void __iomem *) vmap(exynos_gem->pages, nr_pages,
> -                             VM_MAP, pgprot_writecombine(PAGE_KERNEL));
> -     if (!exynos_gem->kvaddr) {
> -             DRM_DEV_ERROR(to_dma_dev(helper->dev),
> -                           "failed to map pages to kernel space.\n");
> -             return -EIO;
> -     }
> -
>       offset = fbi->var.xoffset * fb->format->cpp[0];
>       offset += fbi->var.yoffset * fb->pitches[0];
>  
> @@ -133,18 +122,7 @@ static int exynos_drm_fbdev_create(struct drm_fb_helper 
> *helper,
>  
>       size = mode_cmd.pitches[0] * mode_cmd.height;
>  
> -     exynos_gem = exynos_drm_gem_create(dev, EXYNOS_BO_CONTIG, size);
> -     /*
> -      * If physically contiguous memory allocation fails and if IOMMU is
> -      * supported then try to get buffer from non physically contiguous
> -      * memory area.
> -      */
> -     if (IS_ERR(exynos_gem) && is_drm_iommu_supported(dev)) {
> -             dev_warn(dev->dev, "contiguous FB allocation failed, falling 
> back to non-contiguous\n");
> -             exynos_gem = exynos_drm_gem_create(dev, EXYNOS_BO_NONCONTIG,
> -                                                size);
> -     }
> -
> +     exynos_gem = exynos_drm_gem_create(dev, EXYNOS_BO_WC, size, true);
>       if (IS_ERR(exynos_gem))
>               return PTR_ERR(exynos_gem);
>  
> @@ -229,12 +207,8 @@ int exynos_drm_fbdev_init(struct drm_device *dev)
>  static void exynos_drm_fbdev_destroy(struct drm_device *dev,
>                                     struct drm_fb_helper *fb_helper)
>  {
> -     struct exynos_drm_fbdev *exynos_fbd = to_exynos_fbdev(fb_helper);
> -     struct exynos_drm_gem *exynos_gem = exynos_fbd->exynos_gem;
>       struct drm_framebuffer *fb;
>  
> -     vunmap(exynos_gem->kvaddr);
> -
>       /* release drm framebuffer and real buffer */
>       if (fb_helper->fb && fb_helper->fb->funcs) {
>               fb = fb_helper->fb;
> diff --git a/drivers/gpu/drm/exynos/exynos_drm_gem.c 
> b/drivers/gpu/drm/exynos/exynos_drm_gem.c
> index 9d4e4d321bda..3c2732380517 100644
> --- a/drivers/gpu/drm/exynos/exynos_drm_gem.c
> +++ b/drivers/gpu/drm/exynos/exynos_drm_gem.c
> @@ -17,28 +17,23 @@
>  #include "exynos_drm_drv.h"
>  #include "exynos_drm_gem.h"
>  
> -static int exynos_drm_alloc_buf(struct exynos_drm_gem *exynos_gem)
> +static int exynos_drm_alloc_buf(struct exynos_drm_gem *exynos_gem, bool 
> kvmap)
>  {
>       struct drm_device *dev = exynos_gem->base.dev;
> -     unsigned long attr;
> -     unsigned int nr_pages;
> -     struct sg_table sgt;
> -     int ret = -ENOMEM;
> +     unsigned long attr = 0;
>  
>       if (exynos_gem->dma_addr) {
>               DRM_DEV_DEBUG_KMS(to_dma_dev(dev), "already allocated.\n");
>               return 0;
>       }
>  
> -     exynos_gem->dma_attrs = 0;
> -
>       /*
>        * if EXYNOS_BO_CONTIG, fully physically contiguous memory
>        * region will be allocated else physically contiguous
>        * as possible.
>        */
>       if (!(exynos_gem->flags & EXYNOS_BO_NONCONTIG))
> -             exynos_gem->dma_attrs |= DMA_ATTR_FORCE_CONTIGUOUS;
> +             attr |= DMA_ATTR_FORCE_CONTIGUOUS;
>  
>       /*
>        * if EXYNOS_BO_WC or EXYNOS_BO_NONCACHABLE, writecombine mapping
> @@ -46,61 +41,29 @@ static int exynos_drm_alloc_buf(struct exynos_drm_gem 
> *exynos_gem)
>        */
>       if (exynos_gem->flags & EXYNOS_BO_WC ||
>                       !(exynos_gem->flags & EXYNOS_BO_CACHABLE))
> -             attr = DMA_ATTR_WRITE_COMBINE;
> +             attr |= DMA_ATTR_WRITE_COMBINE;
>       else
> -             attr = DMA_ATTR_NON_CONSISTENT;
> -
> -     exynos_gem->dma_attrs |= attr;
> -     exynos_gem->dma_attrs |= DMA_ATTR_NO_KERNEL_MAPPING;
> -
> -     nr_pages = exynos_gem->size >> PAGE_SHIFT;
> +             attr |= DMA_ATTR_NON_CONSISTENT;
>  
> -     exynos_gem->pages = kvmalloc_array(nr_pages, sizeof(struct page *),
> -                     GFP_KERNEL | __GFP_ZERO);
> -     if (!exynos_gem->pages) {
> -             DRM_DEV_ERROR(to_dma_dev(dev), "failed to allocate pages.\n");
> -             return -ENOMEM;
> -     }
> +     /* FBDev emulation requires kernel mapping */
> +     if (!kvmap)
> +             attr |= DMA_ATTR_NO_KERNEL_MAPPING;
>  
> +     exynos_gem->dma_attrs = attr;
>       exynos_gem->cookie = dma_alloc_attrs(to_dma_dev(dev), exynos_gem->size,
>                                            &exynos_gem->dma_addr, GFP_KERNEL,
>                                            exynos_gem->dma_attrs);
>       if (!exynos_gem->cookie) {
>               DRM_DEV_ERROR(to_dma_dev(dev), "failed to allocate buffer.\n");
> -             goto err_free;
> -     }
> -
> -     ret = dma_get_sgtable_attrs(to_dma_dev(dev), &sgt, exynos_gem->cookie,
> -                                 exynos_gem->dma_addr, exynos_gem->size,
> -                                 exynos_gem->dma_attrs);
> -     if (ret < 0) {
> -             DRM_DEV_ERROR(to_dma_dev(dev), "failed to get sgtable.\n");
> -             goto err_dma_free;
> -     }
> -
> -     if (drm_prime_sg_to_page_addr_arrays(&sgt, exynos_gem->pages, NULL,
> -                                          nr_pages)) {
> -             DRM_DEV_ERROR(to_dma_dev(dev), "invalid sgtable.\n");
> -             ret = -EINVAL;
> -             goto err_sgt_free;
> +             return -ENOMEM;
>       }
>  
> -     sg_free_table(&sgt);
> +     if (kvmap)
> +             exynos_gem->kvaddr = exynos_gem->cookie;
>  
>       DRM_DEV_DEBUG_KMS(to_dma_dev(dev), "dma_addr(0x%lx), size(0x%lx)\n",
>                       (unsigned long)exynos_gem->dma_addr, exynos_gem->size);
> -
>       return 0;
> -
> -err_sgt_free:
> -     sg_free_table(&sgt);
> -err_dma_free:
> -     dma_free_attrs(to_dma_dev(dev), exynos_gem->size, exynos_gem->cookie,
> -                    exynos_gem->dma_addr, exynos_gem->dma_attrs);
> -err_free:
> -     kvfree(exynos_gem->pages);
> -
> -     return ret;
>  }
>  
>  static void exynos_drm_free_buf(struct exynos_drm_gem *exynos_gem)
> @@ -118,8 +81,6 @@ static void exynos_drm_free_buf(struct exynos_drm_gem 
> *exynos_gem)
>       dma_free_attrs(to_dma_dev(dev), exynos_gem->size, exynos_gem->cookie,
>                       (dma_addr_t)exynos_gem->dma_addr,
>                       exynos_gem->dma_attrs);
> -
> -     kvfree(exynos_gem->pages);
>  }
>  
>  static int exynos_drm_gem_handle_create(struct drm_gem_object *obj,
> @@ -203,7 +164,8 @@ static struct exynos_drm_gem *exynos_drm_gem_init(struct 
> drm_device *dev,
>  
>  struct exynos_drm_gem *exynos_drm_gem_create(struct drm_device *dev,
>                                            unsigned int flags,
> -                                          unsigned long size)
> +                                          unsigned long size,
> +                                          bool kvmap)
>  {
>       struct exynos_drm_gem *exynos_gem;
>       int ret;
> @@ -237,7 +199,7 @@ struct exynos_drm_gem *exynos_drm_gem_create(struct 
> drm_device *dev,
>       /* set memory type and cache attribute from user side. */
>       exynos_gem->flags = flags;
>  
> -     ret = exynos_drm_alloc_buf(exynos_gem);
> +     ret = exynos_drm_alloc_buf(exynos_gem, kvmap);
>       if (ret < 0) {
>               drm_gem_object_release(&exynos_gem->base);
>               kfree(exynos_gem);
> @@ -254,7 +216,7 @@ int exynos_drm_gem_create_ioctl(struct drm_device *dev, 
> void *data,
>       struct exynos_drm_gem *exynos_gem;
>       int ret;
>  
> -     exynos_gem = exynos_drm_gem_create(dev, args->flags, args->size);
> +     exynos_gem = exynos_drm_gem_create(dev, args->flags, args->size, false);
>       if (IS_ERR(exynos_gem))
>               return PTR_ERR(exynos_gem);
>  
> @@ -365,7 +327,7 @@ int exynos_drm_gem_dumb_create(struct drm_file *file_priv,
>       else
>               flags = EXYNOS_BO_CONTIG | EXYNOS_BO_WC;
>  
> -     exynos_gem = exynos_drm_gem_create(dev, flags, args->size);
> +     exynos_gem = exynos_drm_gem_create(dev, flags, args->size, false);
>       if (IS_ERR(exynos_gem)) {
>               dev_warn(dev->dev, "FB allocation failed.\n");
>               return PTR_ERR(exynos_gem);
> @@ -442,11 +404,24 @@ struct drm_gem_object 
> *exynos_drm_gem_prime_import(struct drm_device *dev,
>  struct sg_table *exynos_drm_gem_prime_get_sg_table(struct drm_gem_object 
> *obj)
>  {
>       struct exynos_drm_gem *exynos_gem = to_exynos_gem(obj);
> -     int npages;
> +     struct drm_device *drm_dev = obj->dev;
> +     struct sg_table *sgt;
> +     int ret;
> +
> +     sgt = kzalloc(sizeof(*sgt), GFP_KERNEL);
> +     if (!sgt)
> +             return ERR_PTR(-ENOMEM);
>  
> -     npages = exynos_gem->size >> PAGE_SHIFT;
> +     ret = dma_get_sgtable_attrs(to_dma_dev(drm_dev), sgt, 
> exynos_gem->cookie,
> +                                 exynos_gem->dma_addr, exynos_gem->size,
> +                                 exynos_gem->dma_attrs);
> +     if (ret) {
> +             DRM_ERROR("failed to get sgtable, %d\n", ret);
> +             kfree(sgt);
> +             return ERR_PTR(ret);
> +     }
>  
> -     return drm_prime_pages_to_sg(exynos_gem->pages, npages);
> +     return sgt;
>  }
>  
>  struct drm_gem_object *
> @@ -455,8 +430,6 @@ exynos_drm_gem_prime_import_sg_table(struct drm_device 
> *dev,
>                                    struct sg_table *sgt)
>  {
>       struct exynos_drm_gem *exynos_gem;
> -     int npages;
> -     int ret;
>  
>       if (sgt->nents != 1) {
>               dma_addr_t next_addr = sg_dma_address(sgt->sgl);
> @@ -476,26 +449,8 @@ exynos_drm_gem_prime_import_sg_table(struct drm_device 
> *dev,
>       }
>  
>       exynos_gem = exynos_drm_gem_init(dev, attach->dmabuf->size);
> -     if (IS_ERR(exynos_gem)) {
> -             ret = PTR_ERR(exynos_gem);
> -             return ERR_PTR(ret);
> -     }
> -
> -     exynos_gem->dma_addr = sg_dma_address(sgt->sgl);
> -
> -     npages = exynos_gem->size >> PAGE_SHIFT;
> -     exynos_gem->pages = kvmalloc_array(npages, sizeof(struct page *), 
> GFP_KERNEL);
> -     if (!exynos_gem->pages) {
> -             ret = -ENOMEM;
> -             goto err;
> -     }
> -
> -     ret = drm_prime_sg_to_page_addr_arrays(sgt, exynos_gem->pages, NULL,
> -                                            npages);
> -     if (ret < 0)
> -             goto err_free_large;
> -
> -     exynos_gem->sgt = sgt;
> +     if (IS_ERR(exynos_gem))
> +             return ERR_CAST(exynos_gem);
>  
>       /*
>        * Buffer has been mapped as contiguous into DMA address space,
> @@ -507,14 +462,9 @@ exynos_drm_gem_prime_import_sg_table(struct drm_device 
> *dev,
>       else
>               exynos_gem->flags |= EXYNOS_BO_CONTIG;
>  
> +     exynos_gem->dma_addr = sg_dma_address(sgt->sgl);
> +     exynos_gem->sgt = sgt;
>       return &exynos_gem->base;
> -
> -err_free_large:
> -     kvfree(exynos_gem->pages);
> -err:
> -     drm_gem_object_release(&exynos_gem->base);
> -     kfree(exynos_gem);
> -     return ERR_PTR(ret);
>  }
>  
>  void *exynos_drm_gem_prime_vmap(struct drm_gem_object *obj)
> diff --git a/drivers/gpu/drm/exynos/exynos_drm_gem.h 
> b/drivers/gpu/drm/exynos/exynos_drm_gem.h
> index f00044c0b688..6ef001f890aa 100644
> --- a/drivers/gpu/drm/exynos/exynos_drm_gem.h
> +++ b/drivers/gpu/drm/exynos/exynos_drm_gem.h
> @@ -21,20 +21,15 @@
>   * @base: a gem object.
>   *   - a new handle to this gem object would be created
>   *   by drm_gem_handle_create().
> - * @buffer: a pointer to exynos_drm_gem_buffer object.
> - *   - contain the information to memory region allocated
> - *   by user request or at framebuffer creation.
> - *   continuous memory region allocated by user request
> - *   or at framebuffer creation.
>   * @flags: indicate memory type to allocated buffer and cache attruibute.
>   * @size: size requested from user, in bytes and this size is aligned
>   *   in page unit.
>   * @cookie: cookie returned by dma_alloc_attrs
> - * @kvaddr: kernel virtual address to allocated memory region.
> + * @kvaddr: kernel virtual address to allocated memory region (for fbdev)
>   * @dma_addr: bus address(accessed by dma) to allocated memory region.
>   *   - this address could be physical address without IOMMU and
>   *   device address with IOMMU.
> - * @pages: Array of backing pages.
> + * @dma_attrs: attrs passed dma mapping framework
>   * @sgt: Imported sg_table.
>   *
>   * P.S. this object would be transferred to user as kms_bo.handle so
> @@ -48,7 +43,6 @@ struct exynos_drm_gem {
>       void __iomem            *kvaddr;
>       dma_addr_t              dma_addr;
>       unsigned long           dma_attrs;
> -     struct page             **pages;
>       struct sg_table         *sgt;
>  };
>  
> @@ -58,7 +52,8 @@ void exynos_drm_gem_destroy(struct exynos_drm_gem 
> *exynos_gem);
>  /* create a new buffer with gem object */
>  struct exynos_drm_gem *exynos_drm_gem_create(struct drm_device *dev,
>                                            unsigned int flags,
> -                                          unsigned long size);
> +                                          unsigned long size,
> +                                          bool kvmap);
>  
>  /*
>   * request gem object creation and buffer allocation as the size
> 
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