[PATCH 1/7] ttm/radeon/nouveau: Check the DMA address from TTM against known value.

[Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>]

. instead of checking against the DMA_ERROR_CODE value which is
per-platform specific. The zero value is a known invalid value
that the TTM layer sets on the dma_address array if it is not
used (ttm_tt_alloc_page_directory calls drm_calloc_large which
creates a page with GFP_ZERO).

We can't use pci_dma_mapping_error as that is IOMMU
specific (some check for a specific physical address, some
for ranges, some just do a check against zero).

Also update the comments in the header about the true state
of that parameter.

Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
---
 drivers/gpu/drm/nouveau/nouveau_sgdma.c |    3 +--
 drivers/gpu/drm/radeon/radeon_gart.c    |    4 +---
 include/drm/ttm/ttm_page_alloc.h        |    4 ++--
 3 files changed, 4 insertions(+), 7 deletions(-)

diff --git a/drivers/gpu/drm/nouveau/nouveau_sgdma.c b/drivers/gpu/drm/nouveau/nouveau_sgdma.c
index 82fad91..9b570c3 100644
--- a/drivers/gpu/drm/nouveau/nouveau_sgdma.c
+++ b/drivers/gpu/drm/nouveau/nouveau_sgdma.c
@@ -42,8 +42,7 @@ nouveau_sgdma_populate(struct ttm_backend *be, unsigned long num_pages,
 
 	nvbe->nr_pages = 0;
 	while (num_pages--) {
-		/* this code path isn't called and is incorrect anyways */
-		if (0) { /*dma_addrs[nvbe->nr_pages] != DMA_ERROR_CODE)*/
+		if (dma_addrs[nvbe->nr_pages] != 0) {
 			nvbe->pages[nvbe->nr_pages] =
 					dma_addrs[nvbe->nr_pages];
 		 	nvbe->ttm_alloced[nvbe->nr_pages] = true;
diff --git a/drivers/gpu/drm/radeon/radeon_gart.c b/drivers/gpu/drm/radeon/radeon_gart.c
index a533f52..068ba09 100644
--- a/drivers/gpu/drm/radeon/radeon_gart.c
+++ b/drivers/gpu/drm/radeon/radeon_gart.c
@@ -181,9 +181,7 @@ int radeon_gart_bind(struct radeon_device *rdev, unsigned offset,
 	p = t / (PAGE_SIZE / RADEON_GPU_PAGE_SIZE);
 
 	for (i = 0; i < pages; i++, p++) {
-		/* we reverted the patch using dma_addr in TTM for now but this
-		 * code stops building on alpha so just comment it out for now */
-		if (0) { /*dma_addr[i] != DMA_ERROR_CODE) */
+		if (dma_addr[i] != 0) {
 			rdev->gart.ttm_alloced[p] = true;
 			rdev->gart.pages_addr[p] = dma_addr[i];
 		} else {
diff --git a/include/drm/ttm/ttm_page_alloc.h b/include/drm/ttm/ttm_page_alloc.h
index 8062890..0017b17 100644
--- a/include/drm/ttm/ttm_page_alloc.h
+++ b/include/drm/ttm/ttm_page_alloc.h
@@ -36,7 +36,7 @@
  * @flags: ttm flags for page allocation.
  * @cstate: ttm caching state for the page.
  * @count: number of pages to allocate.
- * @dma_address: The DMA (bus) address of pages (if TTM_PAGE_FLAG_DMA32 set).
+ * @dma_address: The DMA (bus) address of pages - (by default zero).
  */
 int ttm_get_pages(struct list_head *pages,
 		  int flags,
@@ -51,7 +51,7 @@ int ttm_get_pages(struct list_head *pages,
  * count.
  * @flags: ttm flags for page allocation.
  * @cstate: ttm caching state.
- * @dma_address: The DMA (bus) address of pages (if TTM_PAGE_FLAG_DMA32 set).
+ * @dma_address: The DMA (bus) address of pages (by default zero).
  */
 void ttm_put_pages(struct list_head *pages,
 		   unsigned page_count,
-- 
1.7.4.1