[PATCH] Revert "drm/nouveau: fix dma syncing warning with debugging on."

[Tobias]

This reverts commit f295c8cfec833c2707ff1512da10d65386dde7af.

Starting with commit f295c8cfec833c2707ff1512da10d65386dde7af
("drm/nouveau: fix dma syncing warning with debugging on.")
the following oops occures:

   BUG: kernel NULL pointer dereference, address: 0000000000000000
   #PF: supervisor read access in kernel mode
   #PF: error_code(0x0000) - not-present page
   PGD 0 P4D 0
   Oops: 0000 [#1] PREEMPT SMP PTI
   CPU: 6 PID: 1013 Comm: Xorg.bin Tainted: G E     5.11.0-desktop-rc0+ #2
   Hardware name: Acer Aspire VN7-593G/Pluto_KLS, BIOS V1.11 08/01/2018
   RIP: 0010:nouveau_bo_sync_for_device+0x40/0xb0 [nouveau]
   Call Trace:
    nouveau_bo_validate+0x5d/0x80 [nouveau]
    nouveau_gem_ioctl_pushbuf+0x662/0x1120 [nouveau]
    ? nouveau_gem_ioctl_new+0xf0/0xf0 [nouveau]
    drm_ioctl_kernel+0xa6/0xf0 [drm]
    drm_ioctl+0x1f4/0x3a0 [drm]
    ? nouveau_gem_ioctl_new+0xf0/0xf0 [nouveau]
    nouveau_drm_ioctl+0x50/0xa0 [nouveau]
    __x64_sys_ioctl+0x7e/0xb0
    do_syscall_64+0x33/0x80
    entry_SYSCALL_64_after_hwframe+0x44/0xae
   ---[ end trace ccfb1e7f4064374f ]---
   RIP: 0010:nouveau_bo_sync_for_device+0x40/0xb0 [nouveau]

Reverting the commit, fixes the issue!

Signed-off-by: Tobias Klausmann <tobias.klausmann at freenet.de>
---
 drivers/gpu/drm/nouveau/nouveau_bo.c | 35 +++++-----------------------
 1 file changed, 6 insertions(+), 29 deletions(-)

diff --git a/drivers/gpu/drm/nouveau/nouveau_bo.c b/drivers/gpu/drm/nouveau/nouveau_bo.c
index 2375711877cf..33dc886d1d6d 100644
--- a/drivers/gpu/drm/nouveau/nouveau_bo.c
+++ b/drivers/gpu/drm/nouveau/nouveau_bo.c
@@ -547,7 +547,7 @@ nouveau_bo_sync_for_device(struct nouveau_bo *nvbo)
 {
 	struct nouveau_drm *drm = nouveau_bdev(nvbo->bo.bdev);
 	struct ttm_tt *ttm_dma = (struct ttm_tt *)nvbo->bo.ttm;
-	int i, j;
+	int i;
 
 	if (!ttm_dma)
 		return;
@@ -556,21 +556,10 @@ nouveau_bo_sync_for_device(struct nouveau_bo *nvbo)
 	if (nvbo->force_coherent)
 		return;
 
-	for (i = 0; i < ttm_dma->num_pages; ++i) {
-		struct page *p = ttm_dma->pages[i];
-		size_t num_pages = 1;
-
-		for (j = i + 1; j < ttm_dma->num_pages; ++j) {
-			if (++p != ttm_dma->pages[j])
-				break;
-
-			++num_pages;
-		}
+	for (i = 0; i < ttm_dma->num_pages; i++)
 		dma_sync_single_for_device(drm->dev->dev,
 					   ttm_dma->dma_address[i],
-					   num_pages * PAGE_SIZE, DMA_TO_DEVICE);
-		i += num_pages;
-	}
+					   PAGE_SIZE, DMA_TO_DEVICE);
 }
 
 void
@@ -578,7 +567,7 @@ nouveau_bo_sync_for_cpu(struct nouveau_bo *nvbo)
 {
 	struct nouveau_drm *drm = nouveau_bdev(nvbo->bo.bdev);
 	struct ttm_tt *ttm_dma = (struct ttm_tt *)nvbo->bo.ttm;
-	int i, j;
+	int i;
 
 	if (!ttm_dma)
 		return;
@@ -587,21 +576,9 @@ nouveau_bo_sync_for_cpu(struct nouveau_bo *nvbo)
 	if (nvbo->force_coherent)
 		return;
 
-	for (i = 0; i < ttm_dma->num_pages; ++i) {
-		struct page *p = ttm_dma->pages[i];
-		size_t num_pages = 1;
-
-		for (j = i + 1; j < ttm_dma->num_pages; ++j) {
-			if (++p != ttm_dma->pages[j])
-				break;
-
-			++num_pages;
-		}
-
+	for (i = 0; i < ttm_dma->num_pages; i++)
 		dma_sync_single_for_cpu(drm->dev->dev, ttm_dma->dma_address[i],
-					num_pages * PAGE_SIZE, DMA_FROM_DEVICE);
-		i += num_pages;
-	}
+					PAGE_SIZE, DMA_FROM_DEVICE);
 }
 
 void nouveau_bo_add_io_reserve_lru(struct ttm_buffer_object *bo)
-- 
2.30.1