I have the same problem in debian 9 with optimus laptop with:

Linux debian-p 4.9.0-3-amd64 #1 SMP Debian 4.9.30-2+deb9u2 (2017-06-26) x86_64 GNU/Linux

00:02.0 VGA compatible controller: Intel Corporation 4th Gen Core Processor Integrated Graphics Controller (rev 06)
	Subsystem: CLEVO/KAPOK Computer 4th Gen Core Processor Integrated Graphics Controller
	Kernel driver in use: i915
	Kernel modules: i915

01:00.0 3D controller: NVIDIA Corporation GM107M [GeForce GTX 860M] (rev a2)
	Subsystem: CLEVO/KAPOK Computer GM107M [GeForce GTX 860M]
	Kernel driver in use: nouveau
	Kernel modules: nouveau


[    4.426265] nouveau 0000:01:00.0: enabling device (0006 -> 0007)
[    4.426363] nouveau 0000:01:00.0: NVIDIA GM107 (117120a2)
[    4.577739] nouveau 0000:01:00.0: bios: version 82.07.27.00.0d
[    4.682139] nouveau 0000:01:00.0: fb: 2048 MiB GDDR5
[    4.682195] nouveau 0000:01:00.0: priv: HUB0: 10ecc0 ffffffff (1f40822c)
[    6.223147] nouveau 0000:01:00.0: DRM: VRAM: 2048 MiB
[    6.223148] nouveau 0000:01:00.0: DRM: GART: 1048576 MiB
[    6.223150] nouveau 0000:01:00.0: DRM: Pointer to TMDS table invalid
[    6.223172] nouveau 0000:01:00.0: DRM: DCB version 4.0
[    6.223173] nouveau 0000:01:00.0: DRM: Pointer to flat panel table invalid
[    6.354290] nouveau 0000:01:00.0: DRM: MM: using COPY for buffer copies
[    6.354295] [drm] Initialized nouveau 1.3.1 20120801 for 0000:01:00.0 on minor 1
[   11.999017] nouveau 0000:01:00.0: DRM: evicting buffers...
[   11.999018] nouveau 0000:01:00.0: DRM: waiting for kernel channels to go idle...
[   11.999032] nouveau 0000:01:00.0: DRM: suspending client object trees...
[   12.001747] nouveau 0000:01:00.0: DRM: suspending kernel object tree...
[   13.482763] nouveau 0000:01:00.0: DRM: resuming kernel object tree...
[   13.616386] nouveau 0000:01:00.0: priv: HUB0: 10ecc0 ffffffff (1940822c)
[   13.636763] nouveau 0000:01:00.0: DRM: resuming client object trees...
[   20.959400] nouveau 0000:01:00.0: DRM: evicting buffers...
[   20.959404] nouveau 0000:01:00.0: DRM: waiting for kernel channels to go idle...
[   20.959425] nouveau 0000:01:00.0: DRM: suspending client object trees...
[   20.962348] nouveau 0000:01:00.0: DRM: suspending kernel object tree...
[   98.386653] nouveau 0000:01:00.0: DRM: resuming kernel object tree...
[   98.524256] nouveau 0000:01:00.0: priv: HUB0: 10ecc0 ffffffff (1940822c)
[   98.544654] nouveau 0000:01:00.0: DRM: resuming client object trees...
[  103.823552] nouveau 0000:01:00.0: DRM: evicting buffers...
[  103.823556] nouveau 0000:01:00.0: DRM: waiting for kernel channels to go idle...
[  103.823578] nouveau 0000:01:00.0: DRM: suspending client object trees...
[  103.826577] nouveau 0000:01:00.0: DRM: suspending kernel object tree...
[  448.704642] nouveau 0000:01:00.0: DRM: resuming kernel object tree...
[  448.838020] nouveau 0000:01:00.0: priv: HUB0: 10ecc0 ffffffff (1940822c)
[  448.858646] nouveau 0000:01:00.0: DRM: resuming client object trees...
[  454.709394] nouveau 0000:01:00.0: DRM: evicting buffers...
[  454.709398] nouveau 0000:01:00.0: DRM: waiting for kernel channels to go idle...
[  454.709420] nouveau 0000:01:00.0: DRM: suspending client object trees...
[  454.712353] nouveau 0000:01:00.0: DRM: suspending kernel object tree...
[  640.453724] nouveau 0000:01:00.0: DRM: resuming kernel object tree...
[  640.586690] nouveau 0000:01:00.0: priv: HUB0: 10ecc0 ffffffff (1940822c)
[  640.607062] nouveau 0000:01:00.0: DRM: resuming client object trees...
[  645.786533] nouveau 0000:01:00.0: DRM: evicting buffers...
[  645.786536] nouveau 0000:01:00.0: DRM: waiting for kernel channels to go idle...
[  645.786559] nouveau 0000:01:00.0: DRM: suspending client object trees...
[  645.789499] nouveau 0000:01:00.0: DRM: suspending kernel object tree...
[ 1005.984365] nouveau 0000:01:00.0: DRM: resuming kernel object tree...
[ 1006.117273] nouveau 0000:01:00.0: priv: HUB0: 10ecc0 ffffffff (1940822c)
[ 1006.137633] nouveau 0000:01:00.0: DRM: resuming client object trees...
[ 1017.760771] nouveau 0000:01:00.0: DRM: evicting buffers...
[ 1017.823180] nouveau 0000:01:00.0: DRM: waiting for kernel channels to go idle...
[ 1017.823200] nouveau 0000:01:00.0: DRM: suspending client object trees...
[ 1017.826018] nouveau 0000:01:00.0: DRM: suspending kernel object tree...

If I can help, tell me how.