From: Ben Skeggs Date: Mon, 7 Jun 2010 03:59:40 +0000 (+1000) Subject: drm/nv50: fix iommu errors caused by device reading from address 0 X-Git-Tag: cont_sys_log_2~10^2~2 X-Git-Url: http://ftp.safe.ca/?p=safe%2Fjmp%2Flinux-2.6;a=commitdiff_plain;h=4eb3033c72099fab3536ed8ac54a5dc99f0832d7 drm/nv50: fix iommu errors caused by device reading from address 0 Signed-off-by: Ben Skeggs Signed-off-by: Dave Airlie --- diff --git a/drivers/gpu/drm/nouveau/nv50_fb.c b/drivers/gpu/drm/nouveau/nv50_fb.c index a95e694..32611bd 100644 --- a/drivers/gpu/drm/nouveau/nv50_fb.c +++ b/drivers/gpu/drm/nouveau/nv50_fb.c @@ -6,10 +6,16 @@ int nv50_fb_init(struct drm_device *dev) { - /* This is needed to get meaningful information from 100c90 - * on traps. No idea what these values mean exactly. */ struct drm_nouveau_private *dev_priv = dev->dev_private; + /* Not a clue what this is exactly. Without pointing it at a + * scratch page, VRAM->GART blits with M2MF (as in DDX DFS) + * cause IOMMU "read from address 0" errors (rh#561267) + */ + nv_wr32(dev, 0x100c08, dev_priv->gart_info.sg_dummy_bus >> 8); + + /* This is needed to get meaningful information from 100c90 + * on traps. No idea what these values mean exactly. */ switch (dev_priv->chipset) { case 0x50: nv_wr32(dev, 0x100c90, 0x0707ff);