drm/radeon/kms: set gart pages to invalid on unbind and point to dummy page

this uses a new entrypoint to invalidate gart entries instead of using 0.
Changed to rather than pointing to 0 address point empty entry to dummy
page. This might help to avoid hard lockup if for some wrong
reasons GPU try to access unmapped GART entry.

I'm not 100% sure this is going to work, we probably need to allocate
a dummy page and point all the GTT entries at it similiar to what AGP does.
but we can test this first I suppose.

Signed-off-by: Jerome Glisse <jglisse@redhat.com>
Signed-off-by: Dave Airlie <airlied@redhat.com>

1 files changed, 30 insertions, 2 deletions

diff --git a/drivers/gpu/drm/radeon/radeon_gart.c b/drivers/gpu/drm/radeon/radeon_gart.c
index e73d56e83fa..1770d3c07fd 100644
--- a/drivers/gpu/drm/radeon/radeon_gart.c
+++ b/drivers/gpu/drm/radeon/radeon_gart.c
@@ -139,6 +139,7 @@ void radeon_gart_unbind(struct radeon_device *rdev, unsigned offset,
 	unsigned t;
 	unsigned p;
 	int i, j;
+	u64 page_base;
 
 	if (!rdev->gart.ready) {
 		WARN(1, "trying to unbind memory to unitialized GART !\n");
@@ -151,9 +152,11 @@ void radeon_gart_unbind(struct radeon_device *rdev, unsigned offset,
 			pci_unmap_page(rdev->pdev, rdev->gart.pages_addr[p],
 				       PAGE_SIZE, PCI_DMA_BIDIRECTIONAL);
 			rdev->gart.pages[p] = NULL;
-			rdev->gart.pages_addr[p] = 0;
+			rdev->gart.pages_addr[p] = rdev->dummy_page.addr;
+			page_base = rdev->gart.pages_addr[p];
 			for (j = 0; j < (PAGE_SIZE / RADEON_GPU_PAGE_SIZE); j++, t++) {
-				radeon_gart_set_page(rdev, t, 0);
+				radeon_gart_set_page(rdev, t, page_base);
+				page_base += RADEON_GPU_PAGE_SIZE;
 			}
 		}
 	}
@@ -199,8 +202,26 @@ int radeon_gart_bind(struct radeon_device *rdev, unsigned offset,
 	return 0;
 }
 
+void radeon_gart_restore(struct radeon_device *rdev)
+{
+	int i, j, t;
+	u64 page_base;
+
+	for (i = 0, t = 0; i < rdev->gart.num_cpu_pages; i++) {
+		page_base = rdev->gart.pages_addr[i];
+		for (j = 0; j < (PAGE_SIZE / RADEON_GPU_PAGE_SIZE); j++, t++) {
+			radeon_gart_set_page(rdev, t, page_base);
+			page_base += RADEON_GPU_PAGE_SIZE;
+		}
+	}
+	mb();
+	radeon_gart_tlb_flush(rdev);
+}
+
 int radeon_gart_init(struct radeon_device *rdev)
 {
+	int r, i;
+
 	if (rdev->gart.pages) {
 		return 0;
 	}
@@ -209,6 +230,9 @@ int radeon_gart_init(struct radeon_device *rdev)
 		DRM_ERROR("Page size is smaller than GPU page size!\n");
 		return -EINVAL;
 	}
+	r = radeon_dummy_page_init(rdev);
+	if (r)
+		return r;
 	/* Compute table size */
 	rdev->gart.num_cpu_pages = rdev->mc.gtt_size / PAGE_SIZE;
 	rdev->gart.num_gpu_pages = rdev->mc.gtt_size / RADEON_GPU_PAGE_SIZE;
@@ -227,6 +251,10 @@ int radeon_gart_init(struct radeon_device *rdev)
 		radeon_gart_fini(rdev);
 		return -ENOMEM;
 	}
+	/* set GART entry to point to the dummy page by default */
+	for (i = 0; i < rdev->gart.num_cpu_pages; i++) {
+		rdev->gart.pages_addr[i] = rdev->dummy_page.addr;
+	}
 	return 0;
 }