drm/nv50: fix iommu errors caused by device reading from address 0
[safe/jmp/linux-2.6] / drivers / gpu / drm / nouveau / nv50_fb.c
1 #include "drmP.h"
2 #include "drm.h"
3 #include "nouveau_drv.h"
4 #include "nouveau_drm.h"
5
6 int
7 nv50_fb_init(struct drm_device *dev)
8 {
9         struct drm_nouveau_private *dev_priv = dev->dev_private;
10
11         /* Not a clue what this is exactly.  Without pointing it at a
12          * scratch page, VRAM->GART blits with M2MF (as in DDX DFS)
13          * cause IOMMU "read from address 0" errors (rh#561267)
14          */
15         nv_wr32(dev, 0x100c08, dev_priv->gart_info.sg_dummy_bus >> 8);
16
17         /* This is needed to get meaningful information from 100c90
18          * on traps. No idea what these values mean exactly. */
19         switch (dev_priv->chipset) {
20         case 0x50:
21                 nv_wr32(dev, 0x100c90, 0x0707ff);
22                 break;
23         case 0xa5:
24         case 0xa8:
25                 nv_wr32(dev, 0x100c90, 0x0d0fff);
26                 break;
27         default:
28                 nv_wr32(dev, 0x100c90, 0x1d07ff);
29                 break;
30         }
31
32         return 0;
33 }
34
35 void
36 nv50_fb_takedown(struct drm_device *dev)
37 {
38 }