Ok so I traced this to occuring after you install the nvidia driver. Using the intel card or the nouveau drivers the kernel log was clean. It was only after installing nvidia drivers (I tried various versions, from 367 up to 375) that I saw that in the kernel logs.
Either way, for me it does not seem to be actually affecting anything. My laptop (Precision 5510) is able to drive the external 4k monitor as well as its normal 4k screen. It's also able to push sound to the external 4k monitor (has built in speakers). So sound is working and so is the resolution. This error, while definitely concerning (and it definitely went away when I upgraded to the 4.8.x kernel), doesn't seem to actually affect me negatively.
Additionally, I downgraded back to the original Ubuntu 14.04 based image Dell officially released the Precision 5510 with, to see if they'd custom patched the older kernel or anything, but they hadn't. Same error shows up in the kernel logs on the 14.04 distribution Dell included with the laptop. So they didn't see a need to fix it there either.
Ok so I traced this to occuring after you install the nvidia driver. Using the intel card or the nouveau drivers the kernel log was clean. It was only after installing nvidia drivers (I tried various versions, from 367 up to 375) that I saw that in the kernel logs.
Either way, for me it does not seem to be actually affecting anything. My laptop (Precision 5510) is able to drive the external 4k monitor as well as its normal 4k screen. It's also able to push sound to the external 4k monitor (has built in speakers). So sound is working and so is the resolution. This error, while definitely concerning (and it definitely went away when I upgraded to the 4.8.x kernel), doesn't seem to actually affect me negatively.
Additionally, I downgraded back to the original Ubuntu 14.04 based image Dell officially released the Precision 5510 with, to see if they'd custom patched the older kernel or anything, but they hadn't. Same error shows up in the kernel logs on the 14.04 distribution Dell included with the laptop. So they didn't see a need to fix it there either.