https://listnr.corp.google.com/report/85909852148


Rough timeline:
* Yesterday at the end of my bus ride (near 5pm), I was using my  
Chromebook.  Suddenly the screen went off.
* I was about at the end of my bus ride, so I just shut the screen.
* I opened my device this morning and screen was still black.
* Tried a few s2r cycles (via lid closing) and it seemed that s2r was  
working but screen wouldn't come back.
* I did Alt-VolUp-X once.  Waited ~5 seconds.  Nothing.
* I did Alt-VolUp-X again.  It rebooted.

Upon reboot I looked at console-ramoops and /var/log/messages.  First thing  
in /var/log/messages that looks relevant:

2019-01-14T18:54:06.381289-06:00 ERR kernel: [100891.118166] rk_iommu ff903f00.iommu: Page fault at 0x0000000000008000 of type read
2019-01-14T18:54:06.381343-06:00 ERR kernel: [100891.118197] rk_iommu ff903f00.iommu: iova = 0x0000000000008000: dte_index: 0x0 pte_index: 0x8 page_offset: 0x0
2019-01-14T18:54:06.381350-06:00 ERR kernel: [100891.118209] rk_iommu ff903f00.iommu: mmu_dte_addr: 0x00000000ed8a1000 dte@0x00000000ed8a1000: 0xeb0d3001 valid: 1 pte@0x00000000eb0d3020: 0x16302006 valid: 0 page@0x0000000000000000 flags: 0x0
2019-01-14T18:54:09.414024-06:00 ERR kernel: [100894.150789] rk_iommu ff903f00.iommu: Page fault at 0x0000000000008000 of type read
2019-01-14T18:54:09.414092-06:00 ERR kernel: [100894.150825] rk_iommu ff903f00.iommu: iova = 0x0000000000008000: dte_index: 0x0 pte_index: 0x8 page_offset: 0x0
2019-01-14T18:54:09.414107-06:00 ERR kernel: [100894.150844] rk_iommu ff903f00.iommu: mmu_dte_addr: 0x00000000ed8a1000 dte@0x00000000ed8a1000: 0xeb0d3001 valid: 1 pte@0x00000000eb0d3020: 0x16302006 valid: 0 page@0x0000000000000000 flags: 0x0