drm/exynos: remove 'pages' and 'page_size' elements in exynos gem buffer

Changelog v2:

Removed redundant check for invalid sgl.
Added check for valid page_offset in the beginning of exynos_drm_gem_map_buf.

Changelog v1:

The 'pages' structure is not required since we can use the 'sgt'. Even for
CONTIG buffers, a SGT is created (which will have just one sgl). This SGT
can be used during mmap instead of 'pages'. The 'page_size' element of the
structure is also not used anywhere and is removed.
This patch also fixes a memory leak where the 'pages' structure was being
allocated during gem buffer allocation but not being freed during deallocate.

Signed-off-by: Prathyush K <prathyush.k@samsung.com>
Signed-off-by: Inki Dae <inki.dae@samsung.com>
Signed-off-by: Kyungmin Park <kyungmin.park@samsung.com>

drivers/gpu/drm/exynos/exynos_drm_buf.c

@@ -34,8 +34,6 @@ static int lowlevel_buffer_allocate(struct drm_device *dev,
 		unsigned int flags, struct exynos_drm_gem_buf *buf)
 {
 	int ret = 0;
-	unsigned int npages, i = 0;
-	struct scatterlist *sgl;
 	enum dma_attr attr = DMA_ATTR_FORCE_CONTIGUOUS;
 
 	DRM_DEBUG_KMS("%s\n", __FILE__);
@@ -73,22 +71,6 @@ static int lowlevel_buffer_allocate(struct drm_device *dev,
 		goto err_free_sgt;
 	}
 
-	npages = buf->sgt->nents;
-
-	buf->pages = kzalloc(sizeof(struct page) * npages, GFP_KERNEL);
-	if (!buf->pages) {
-		DRM_ERROR("failed to allocate pages.\n");
-		ret = -ENOMEM;
-		goto err_free_table;
-	}
-
-	sgl = buf->sgt->sgl;
-	while (i < npages) {
-		buf->pages[i] = sg_page(sgl);
-		sgl = sg_next(sgl);
-		i++;
-	}
-
 	DRM_DEBUG_KMS("vaddr(0x%lx), dma_addr(0x%lx), size(0x%lx)\n",
 			(unsigned long)buf->kvaddr,
 			(unsigned long)buf->dma_addr,
@@ -96,8 +78,6 @@ static int lowlevel_buffer_allocate(struct drm_device *dev,
 
 	return ret;
 
-err_free_table:
-	sg_free_table(buf->sgt);
 err_free_sgt:
 	kfree(buf->sgt);
 	buf->sgt = NULL;

drivers/gpu/drm/exynos/exynos_drm_buf.h

@@ -34,12 +34,12 @@ struct exynos_drm_gem_buf *exynos_drm_init_buf(struct drm_device *dev,
 void exynos_drm_fini_buf(struct drm_device *dev,
 				struct exynos_drm_gem_buf *buffer);
 
-/* allocate physical memory region and setup sgt and pages. */
+/* allocate physical memory region and setup sgt. */
 int exynos_drm_alloc_buf(struct drm_device *dev,
 				struct exynos_drm_gem_buf *buf,
 				unsigned int flags);
 
-/* release physical memory region, sgt and pages. */
+/* release physical memory region, and sgt. */
 void exynos_drm_free_buf(struct drm_device *dev,
 				unsigned int flags,
 				struct exynos_drm_gem_buf *buffer);

drivers/gpu/drm/exynos/exynos_drm_dmabuf.c

@@ -87,8 +87,7 @@ static struct sg_table *
 		goto err_unlock;
 	}
 
-	DRM_DEBUG_PRIME("buffer size = 0x%lx page_size = 0x%lx\n",
-			buf->size, buf->page_size);
+	DRM_DEBUG_PRIME("buffer size = 0x%lx\n", buf->size);
 
 err_unlock:
 	mutex_unlock(&dev->struct_mutex);

drivers/gpu/drm/exynos/exynos_drm_gem.c

@@ -99,33 +99,22 @@ static int exynos_drm_gem_map_buf(struct drm_gem_object *obj,
 	unsigned long pfn;
 	int i;
 
-	if (exynos_gem_obj->flags & EXYNOS_BO_NONCONTIG) {
 	if (!buf->sgt)
 		return -EINTR;
 
+	if (page_offset >= (buf->size >> PAGE_SHIFT)) {
+		DRM_ERROR("invalid page offset\n");
+		return -EINVAL;
+	}
+
 	sgl = buf->sgt->sgl;
 	for_each_sg(buf->sgt->sgl, sgl, buf->sgt->nents, i) {
-			if (!sgl) {
-				DRM_ERROR("invalid SG table\n");
-				return -EINTR;
-			}
 		if (page_offset < (sgl->length >> PAGE_SHIFT))
 			break;
 		page_offset -=	(sgl->length >> PAGE_SHIFT);
 	}
 
-		if (i >= buf->sgt->nents) {
-			DRM_ERROR("invalid page offset\n");
-			return -EINVAL;
-		}
-
 	pfn = __phys_to_pfn(sg_phys(sgl)) + page_offset;
-	} else {
-		if (!buf->pages)
-			return -EINTR;
-
-		pfn = page_to_pfn(buf->pages[0]) + page_offset;
-	}
 
 	return vm_insert_mixed(vma, f_vaddr, pfn);
 }

drivers/gpu/drm/exynos/exynos_drm_gem.h

@@ -41,8 +41,6 @@
  *	device address with IOMMU.
  * @write: whether pages will be written to by the caller.
  * @sgt: sg table to transfer page data.
- * @pages: contain all pages to allocated memory region.
- * @page_size: could be 4K, 64K or 1MB.
  * @size: size of allocated memory region.
  * @pfnmap: indicate whether memory region from userptr is mmaped with
  *	VM_PFNMAP or not.
@@ -54,8 +52,6 @@ struct exynos_drm_gem_buf {
 	struct dma_attrs	dma_attrs;
 	unsigned int		write;
 	struct sg_table		*sgt;
-	struct page		**pages;
-	unsigned long		page_size;
 	unsigned long		size;
 	bool			pfnmap;
 };