[Nouveau] NVAC "No Signal"

[poma]

Fixes "No Signal" via HDMI from NVIDIA Corporation ION VGA (rev b1)

Ref.
"drm/nouveau/disp/g94: implement workaround for dvi issue on fx380"
https://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/commit/?id=2a4bd8a

The last working Fedora kernel 4.8.0-0.rc0.git3.1.fc25

Patched and tested with:
$ modinfo -n nouveau
/lib/modules/4.8.2-300.fc25.x86_64/updates/nouveau.ko

Tested-by: poma <poma at gmail.com>
---
 drivers/gpu/drm/nouveau/nvkm/engine/disp/nv50.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/nouveau/nvkm/engine/disp/nv50.c b/drivers/gpu/drm/nouveau/nvkm/engine/disp/nv50.c
index fbb8c7d..c9e40e7 100644
--- a/drivers/gpu/drm/nouveau/nvkm/engine/disp/nv50.c
+++ b/drivers/gpu/drm/nouveau/nvkm/engine/disp/nv50.c
@@ -434,7 +434,8 @@ nv50_disp_dptmds_war(struct nvkm_device *device)
 	case 0x96:
 	case 0x98:
 	case 0xaa:
-	case 0xac:
+/* NVIDIA MCP79/MCP7A "No Signal" */
+/*	case 0xac:                */
 		return true;
 	default:
 		break;
-- 
2.7.4