drm/i915/bdw: Split ppgtt initialization up

Like cleanup in an earlier patch, the code becomes much more readable,
and easier to extend if we extract out helper functions for the various
stages of init.

Note that with this patch it becomes really simple, and tempting to begin
using the 'goto out' idiom with explicit free/fini semantics. I've
kept the error path as similar as possible to the cleanup() function to
make sure cleanup is as robust as possible

v2: Remove comment "NB:From here on, ppgtt->base.cleanup() should
function properly"
Update commit message to reflect above

v3: Rebased on top of bugfixes found in the previous patch by Imre
Moved number of pd pages assertion to the proper place (Imre)

v4:
Allocate dma address space for num_pd_pages, not num_pd_entries (Ben)
Don't use gen8_pt_dma_addr after free on error path (Imre)
With new fix from v4 of the previous patch.
Signed-off-by: Ben Widawsky <ben@bwidawsk.net>
Reviewed-by: Imre Deak <imre.deak@intel.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>

drivers/gpu/drm/i915/i915_gem_gtt.c

@@ -365,6 +365,113 @@ static void gen8_ppgtt_cleanup(struct i915_address_space *vm)
 	gen8_ppgtt_free(ppgtt);
 }
 
+static int gen8_ppgtt_allocate_page_tables(struct i915_hw_ppgtt *ppgtt,
+					   const int max_pdp)
+{
+	struct page *pt_pages;
+	const int num_pt_pages = GEN8_PDES_PER_PAGE * max_pdp;
+
+	pt_pages = alloc_pages(GFP_KERNEL, get_order(num_pt_pages << PAGE_SHIFT));
+	if (!pt_pages)
+		return -ENOMEM;
+
+	ppgtt->gen8_pt_pages = pt_pages;
+	ppgtt->num_pt_pages = 1 << get_order(num_pt_pages << PAGE_SHIFT);
+
+	return 0;
+}
+
+static int gen8_ppgtt_allocate_dma(struct i915_hw_ppgtt *ppgtt)
+{
+	int i;
+
+	for (i = 0; i < ppgtt->num_pd_pages; i++) {
+		ppgtt->gen8_pt_dma_addr[i] = kcalloc(GEN8_PDES_PER_PAGE,
+						     sizeof(dma_addr_t),
+						     GFP_KERNEL);
+		if (!ppgtt->gen8_pt_dma_addr[i])
+			return -ENOMEM;
+	}
+
+	return 0;
+}
+
+static int gen8_ppgtt_allocate_page_directories(struct i915_hw_ppgtt *ppgtt,
+						const int max_pdp)
+{
+	ppgtt->pd_pages = alloc_pages(GFP_KERNEL, get_order(max_pdp << PAGE_SHIFT));
+	if (!ppgtt->pd_pages)
+		return -ENOMEM;
+
+	ppgtt->num_pd_pages = 1 << get_order(max_pdp << PAGE_SHIFT);
+	BUG_ON(ppgtt->num_pd_pages > GEN8_LEGACY_PDPS);
+
+	return 0;
+}
+
+static int gen8_ppgtt_alloc(struct i915_hw_ppgtt *ppgtt,
+			    const int max_pdp)
+{
+	int ret;
+
+	ret = gen8_ppgtt_allocate_page_directories(ppgtt, max_pdp);
+	if (ret)
+		return ret;
+
+	ret = gen8_ppgtt_allocate_page_tables(ppgtt, max_pdp);
+	if (ret) {
+		__free_pages(ppgtt->pd_pages, get_order(max_pdp << PAGE_SHIFT));
+		return ret;
+	}
+
+	ppgtt->num_pd_entries = max_pdp * GEN8_PDES_PER_PAGE;
+
+	ret = gen8_ppgtt_allocate_dma(ppgtt);
+	if (ret)
+		gen8_ppgtt_free(ppgtt);
+
+	return ret;
+}
+
+static int gen8_ppgtt_setup_page_directories(struct i915_hw_ppgtt *ppgtt,
+					     const int pd)
+{
+	dma_addr_t pd_addr;
+	int ret;
+
+	pd_addr = pci_map_page(ppgtt->base.dev->pdev,
+			       &ppgtt->pd_pages[pd], 0,
+			       PAGE_SIZE, PCI_DMA_BIDIRECTIONAL);
+
+	ret = pci_dma_mapping_error(ppgtt->base.dev->pdev, pd_addr);
+	if (ret)
+		return ret;
+
+	ppgtt->pd_dma_addr[pd] = pd_addr;
+
+	return 0;
+}
+
+static int gen8_ppgtt_setup_page_tables(struct i915_hw_ppgtt *ppgtt,
+					const int pd,
+					const int pt)
+{
+	dma_addr_t pt_addr;
+	struct page *p;
+	int ret;
+
+	p = &ppgtt->gen8_pt_pages[pd * GEN8_PDES_PER_PAGE + pt];
+	pt_addr = pci_map_page(ppgtt->base.dev->pdev,
+			       p, 0, PAGE_SIZE, PCI_DMA_BIDIRECTIONAL);
+	ret = pci_dma_mapping_error(ppgtt->base.dev->pdev, pt_addr);
+	if (ret)
+		return ret;
+
+	ppgtt->gen8_pt_dma_addr[pd][pt] = pt_addr;
+
+	return 0;
+}
+
 /**
  * GEN8 legacy ppgtt programming is accomplished through a max 4 PDP registers
  * with a net effect resembling a 2-level page table in normal x86 terms. Each
@@ -377,69 +484,30 @@ static void gen8_ppgtt_cleanup(struct i915_address_space *vm)
  */
 static int gen8_ppgtt_init(struct i915_hw_ppgtt *ppgtt, uint64_t size)
 {
-	struct page *pt_pages;
 	const int max_pdp = DIV_ROUND_UP(size, 1 << 30);
-	const int num_pt_pages = GEN8_PDES_PER_PAGE * max_pdp;
-	struct pci_dev *hwdev = ppgtt->base.dev->pdev;
+	const int min_pt_pages = GEN8_PDES_PER_PAGE * max_pdp;
 	int i, j, ret;
 
 	if (size % (1<<30))
 		DRM_INFO("Pages will be wasted unless GTT size (%llu) is divisible by 1GB\n", size);
 
-	/* 1. Do all our allocations for page directories and page tables */
-	ppgtt->pd_pages = alloc_pages(GFP_KERNEL, get_order(max_pdp << PAGE_SHIFT));
-	if (!ppgtt->pd_pages)
-		return -ENOMEM;
-
-	pt_pages = alloc_pages(GFP_KERNEL, get_order(num_pt_pages << PAGE_SHIFT));
-	if (!pt_pages) {
-		__free_pages(ppgtt->pd_pages, get_order(max_pdp << PAGE_SHIFT));
-		return -ENOMEM;
-	}
-
-	ppgtt->gen8_pt_pages = pt_pages;
-	ppgtt->num_pd_pages = 1 << get_order(max_pdp << PAGE_SHIFT);
-	ppgtt->num_pt_pages = 1 << get_order(num_pt_pages << PAGE_SHIFT);
-	ppgtt->num_pd_entries = max_pdp * GEN8_PDES_PER_PAGE;
-	BUG_ON(ppgtt->num_pd_pages > GEN8_LEGACY_PDPS);
-
-	for (i = 0; i < max_pdp; i++) {
-		ppgtt->gen8_pt_dma_addr[i] = kcalloc(GEN8_PDES_PER_PAGE,
-						     sizeof(dma_addr_t),
-						     GFP_KERNEL);
-		if (!ppgtt->gen8_pt_dma_addr[i]) {
-			ret = -ENOMEM;
-			goto bail;
-		}
-	}
+	/* 1. Do all our allocations for page directories and page tables. */
+	ret = gen8_ppgtt_alloc(ppgtt, max_pdp);
+	if (ret)
+		return ret;
 
 	/*
-	 * 2. Create all the DMA mappings for the page directories and page
-	 * tables
+	 * 2. Create DMA mappings for the page directories and page tables.
 	 */
 	for (i = 0; i < max_pdp; i++) {
-		dma_addr_t pd_addr, pt_addr;
-
-		/* Get the page directory mappings */
-		pd_addr = pci_map_page(hwdev, &ppgtt->pd_pages[i], 0,
-				       PAGE_SIZE, PCI_DMA_BIDIRECTIONAL);
-		ret = pci_dma_mapping_error(ppgtt->base.dev->pdev, pd_addr);
+		ret = gen8_ppgtt_setup_page_directories(ppgtt, i);
 		if (ret)
 			goto bail;
 
-		ppgtt->pd_dma_addr[i] = pd_addr;
-
-		/* And the page table mappings per page directory */
 		for (j = 0; j < GEN8_PDES_PER_PAGE; j++) {
-			struct page *p = &pt_pages[i * GEN8_PDES_PER_PAGE + j];
-
-			pt_addr = pci_map_page(hwdev, p, 0, PAGE_SIZE,
-					       PCI_DMA_BIDIRECTIONAL);
-			ret = pci_dma_mapping_error(hwdev, pt_addr);
+			ret = gen8_ppgtt_setup_page_tables(ppgtt, i, j);
 			if (ret)
 				goto bail;
-
-			ppgtt->gen8_pt_dma_addr[i][j] = pt_addr;
 		}
 	}
 
@@ -478,7 +546,7 @@ static int gen8_ppgtt_init(struct i915_hw_ppgtt *ppgtt, uint64_t size)
 			 ppgtt->num_pd_pages, ppgtt->num_pd_pages - max_pdp);
 	DRM_DEBUG_DRIVER("Allocated %d pages for page tables (%lld wasted)\n",
 			 ppgtt->num_pt_pages,
-			 (ppgtt->num_pt_pages - num_pt_pages) +
+			 (ppgtt->num_pt_pages - min_pt_pages) +
 			 size % (1<<30));
 	return 0;