ChromeOS version: 67.0.3396.99
ChromeOS device model: ASUS Chromebit CS10 
10575.58.0 (Official Build) stable-channel veyron_mickey
Case#: 16440653

Monitor info.
Dell 34” Curve U3417W
Viewsonic 27" Monitor
LG 49UH6100: 49-inch 4K UHD HDR Smart LED TV

Description:HDMI video output by the Chromebit with KIOSK app stops and the screen becomes a blank screen.


Steps to reproduce: 
1- Turn on the device 
2- The device launches Chrome Sign Builder.
Config file:https://drive.google.com/open?id=1AeLgT6IFoQyyxE_80XoBoDXIGsE1Vu94OUlQ6L4WeCE 
3- After a random time the Chromebit shows a black screen however the device is still working in the back end as it appears to be Pingable and online in the admin console.
-When I unplug the chromebit from the display, the display then says there is no device present.
- Displaying 4 different pages on one screen and video is off for all 4 quadrants.


Current Behavior / Reproduction: HDMI video output by the Chromebit with KIOSK app stops and the screen becomes a blank screen.

Expected Behavior: 
The image should continue to work.

Workaround: downgrade to M66.
Or power-cycle the chromebit

- Timeframe when issue started: 
The first week was when the customer saw this issue the first time.

- Does it affect all devices? 
At least 4 devices could be affected 

Drive link to logs: 
https://drive.google.com/open?id=1PfIlaGoCbxTabRO_bMlCqBT6S2sBUv9T
07/22/2018 
approximately between 7:25am & 7:45am Eastern. 

2018-07-24T13:54:36.970254-04:00 ALERT kernel: [709938.065657] Unhandled prefetch abort: breakpoint debug exception (0x222) at 0x417bc380
2018-07-24T13:54:36.970279-04:00 ALERT kernel: [709938.065680] Unhandled prefetch abort: breakpoint debug exception (0x222) at 0x417bc380
2018-07-24T13:54:37.180273-04:00 ALERT kernel: [709938.282723] Unhandled prefetch abort: breakpoint debug exception (0x222) at 0x417bc480
2018-07-24T13:54:37.180303-04:00 ALERT kernel: [709938.282750] Unhandled prefetch abort: breakpoint debug exception (0x222) at 0x417bc480
2018-07-24T13:55:40.439201-04:00 INFO crash_reporter[4603]: libminijail[4603]: mount /dev/log -> /dev/log type ''
2018-07-24T13:55:40.624521-04:00 WARNING crash_reporter[4603]: [user] Received crash notification for chrome[1013] sig 11, user 1000 (ignoring call by kernel - chrome crash; waiting for chrome to call us directly)
2018-07-24T13:55:41.730823-04:00 ERR kernel: [710002.824659] mali ffa30000.gpu: Issueing GPU soft-reset because jobs failed to be killed (within 1000 ms) as part of context termination (e.g. process exit)
2018-07-24T13:55:41.730935-04:00 ERR kernel: [710002.824784] mali ffa30000.gpu: Preparing to soft-reset GPU: Waiting (upto 3000 ms) for all jobs to complete soft-stop
2018-07-24T13:55:41.730961-04:00 ERR kernel: [710002.825140] mali ffa30000.gpu: Resetting GPU (allowing up to 500 ms)
2018-07-24T13:55:41.730985-04:00 ERR kernel: [710002.825215] mali ffa30000.gpu: Register state:
2018-07-24T13:55:41.731097-04:00 ERR kernel: [710002.825284] mali ffa30000.gpu:   GPU_IRQ_RAWSTAT=0x00000200 GPU_STATUS=0x00000003
2018-07-24T13:55:41.731123-04:00 ERR kernel: [710002.825359] mali ffa30000.gpu:   JOB_IRQ_RAWSTAT=0x00000000 JOB_IRQ_JS_STATE=0x00000000
2018-07-24T13:55:41.731145-04:00 ERR kernel: [710002.825460] mali ffa30000.gpu:   JS0_STATUS=0x00000000      JS0_HEAD_LO=0x00000000
2018-07-24T13:55:41.731164-04:00 ERR kernel: [710002.825679] mali ffa30000.gpu:   JS1_STATUS=0x00000000      JS1_HEAD_LO=0xac5ada80
2018-07-24T13:55:41.731186-04:00 ERR kernel: [710002.825760] mali ffa30000.gpu:   JS2_STATUS=0x00000000      JS2_HEAD_LO=0x00000000
2018-07-24T13:55:41.731206-04:00 ERR kernel: [710002.825855] mali ffa30000.gpu:   MMU_IRQ_RAWSTAT=0x00000000 GPU_FAULTSTATUS=0x00000000
2018-07-24T13:55:41.731226-04:00 ERR kernel: [710002.825933] mali ffa30000.gpu:   GPU_IRQ_MASK=0x00000000    JOB_IRQ_MASK=0x00000000     MMU_IRQ_MASK=0x00000000
2018-07-24T13:55:41.731249-04:00 ERR kernel: [710002.826014] mali ffa30000.gpu:   PWR_OVERRIDE0=0x00000000   PWR_OVERRIDE1=0x00000000
2018-07-24T13:55:41.731268-04:00 ERR kernel: [710002.826103] mali ffa30000.gpu:   SHADER_CONFIG=0x00010000   L2_MMU_CONFIG=0x00000000
2018-07-24T13:55:41.731287-04:00 ERR kernel: [710002.826191] mali ffa30000.gpu:   TILER_CONFIG=0x00000001    JM_CONFIG=0x00000000
2018-07-24T13:55:41.731306-04:00 ERR kernel: [710002.826356] mali ffa30000.gpu: Reset complete
2018-07-24T13:55:41.836655-04:00 ERR cras_server[1284]: pcm_avail returned frames larger than buf_size: RockchipHDMI: :0,0: 131545 > 131072 for 1 times
2018-07-24T13:55:41.870258-04:00 INFO kernel: [710002.965585] rockchip-vop ff930000.vop: Detached from iommu domain

-policy file
https://drive.google.com/open?id=1ld-aT83xJpvphIq6Jh7qBHg40gGYEnaE

Locally tested.
Looks like the KIOSK app stop working but does not become a black screen.
I will update the test device log file once I verify more details.

I found similar error messages from  crbug.com/768467 , but the case has been closed.