(This is a v2 of patch "drm/nouveau/disp/nv50: Add PFB writes")

This fix a GPU lockup on 9400M (NVAC) when using acceleration, see https://bugs.freedesktop.org/show_bug.cgi?id=27501

v2: - Move code to subdev/fb/nv50.c as suggested by Roy Spliet; - Remove arbitrary writes to 100c18/100c24 as suggested by Roy Spliet; - Replace write to 100c1c of arbitrary value by the address of a scratch page as proposed by Ilia Mirkin; - Remove enabling of bits 16 and 0 as they don't yield in any changes.

Signed-off-by: Pierre Moreau pierre.morrow@free.fr --- drivers/gpu/drm/nouveau/core/subdev/fb/nv50.c | 11 +++++++++++ 1 file changed, 11 insertions(+)

diff --git a/drivers/gpu/drm/nouveau/core/subdev/fb/nv50.c b/drivers/gpu/drm/nouveau/core/subdev/fb/nv50.c index 4150b0d..5c84d13 100644 --- a/drivers/gpu/drm/nouveau/core/subdev/fb/nv50.c +++ b/drivers/gpu/drm/nouveau/core/subdev/fb/nv50.c @@ -289,6 +289,17 @@ nv50_fb_init(struct nouveau_object *object) if (ret) return ret;

+ /* Not a clue what this is exactly. Without enabling bit 1 of + * 100c14, system will lockup while initialising the card + * (#27501) + */ + if (nv_device(priv)->chipset == 0xac) { + if ((nv_rd32(priv, 0x100c14) & 0x00000002) == 0x00000000) { + nv_wr32(priv, 0x100c1c, priv->r100c08 >> 8); + nv_mask(priv, 0x100c14, 0x00000000, 0x00000002); + } + } + /* 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)