drm/radeon/kms: consolidate GART code, fix segfault after GPU lockup V2

After GPU lockup VRAM gart table is unpinned and thus its pointer
becomes unvalid. This patch move the unpin code to a common helper
function and set pointer to NULL so that page update code can check
if it should update GPU page table or not. That way bo still bound
to GART can be unbound (pci_unmap_page for all there page) properly
while there is no need to update the GPU page table.

V2 move the test for null gart out of the loop, small optimization

Signed-off-by: Jerome Glisse <jglisse@redhat.com>
Signed-off-by: Dave Airlie <airlied@redhat.com>
diff --git a/drivers/gpu/drm/radeon/radeon.h b/drivers/gpu/drm/radeon/radeon.h
index e94c6f1..b316b30 100644
--- a/drivers/gpu/drm/radeon/radeon.h
+++ b/drivers/gpu/drm/radeon/radeon.h
@@ -307,30 +307,17 @@
  */
 struct radeon_mc;
 
-struct radeon_gart_table_ram {
-	volatile uint32_t		*ptr;
-};
-
-struct radeon_gart_table_vram {
-	struct radeon_bo		*robj;
-	volatile uint32_t		*ptr;
-};
-
-union radeon_gart_table {
-	struct radeon_gart_table_ram	ram;
-	struct radeon_gart_table_vram	vram;
-};
-
 #define RADEON_GPU_PAGE_SIZE 4096
 #define RADEON_GPU_PAGE_MASK (RADEON_GPU_PAGE_SIZE - 1)
 #define RADEON_GPU_PAGE_SHIFT 12
 
 struct radeon_gart {
 	dma_addr_t			table_addr;
+	struct radeon_bo		*robj;
+	void				*ptr;
 	unsigned			num_gpu_pages;
 	unsigned			num_cpu_pages;
 	unsigned			table_size;
-	union radeon_gart_table		table;
 	struct page			**pages;
 	dma_addr_t			*pages_addr;
 	bool				*ttm_alloced;
@@ -341,6 +328,8 @@
 void radeon_gart_table_ram_free(struct radeon_device *rdev);
 int radeon_gart_table_vram_alloc(struct radeon_device *rdev);
 void radeon_gart_table_vram_free(struct radeon_device *rdev);
+int radeon_gart_table_vram_pin(struct radeon_device *rdev);
+void radeon_gart_table_vram_unpin(struct radeon_device *rdev);
 int radeon_gart_init(struct radeon_device *rdev);
 void radeon_gart_fini(struct radeon_device *rdev);
 void radeon_gart_unbind(struct radeon_device *rdev, unsigned offset,
@@ -348,6 +337,7 @@
 int radeon_gart_bind(struct radeon_device *rdev, unsigned offset,
 		     int pages, struct page **pagelist,
 		     dma_addr_t *dma_addr);
+void radeon_gart_restore(struct radeon_device *rdev);
 
 
 /*
@@ -1445,8 +1435,6 @@
 /* AGP */
 extern int radeon_gpu_reset(struct radeon_device *rdev);
 extern void radeon_agp_disable(struct radeon_device *rdev);
-extern int radeon_gart_table_vram_pin(struct radeon_device *rdev);
-extern void radeon_gart_restore(struct radeon_device *rdev);
 extern int radeon_modeset_init(struct radeon_device *rdev);
 extern void radeon_modeset_fini(struct radeon_device *rdev);
 extern bool radeon_card_posted(struct radeon_device *rdev);