drm/exynos: gem: Get rid of the internal 'pages' array

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.

Suggested-by: Christian König <[email protected]>
Signed-off-by: Marek Szyprowski <[email protected]>
Signed-off-by: Inki Dae <[email protected]>

Author: mszyprow

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;

drivers/gpu/drm/exynos/exynos_drm_gem.c

@@ -17,90 +17,53 @@
 #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
 	 * else cachable mapping.
 	 */
 	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)
 		return ERR_PTR(-EINVAL);
@@ -482,26 +455,8 @@ 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,
@@ -513,14 +468,9 @@ 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)

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