Full PowerTOP bits: https://gist.github.com/projectgus/e79923530392517c4e55064bb07b778d
(On the offchance anyone sees this and decides to buy an XPS 13 on this basis - it's still been a trip back to running Linux 10-15 years ago. I get random hard locks coming out of suspend, screen flickers when the laptop gets hot, glitchy touchpad driver, USB Type C is WIP, etc. Have spent way too much time compiling kernels and trawling forums. I wish I'd done my homework beforehand instead of thinking "well, Dell ships Linux on it from factory. How bad can it be?")
Kernel 4.7 seems to do PC8 OK
Dell XPS 13 9350, 1.4.0 BIOS, Intel WiFi. The only change from kernel defaults is i915.enable_rc6=1.
Idle-ish system with normal processes running, screen on:
C2 (pc2) 18.5%
C3 (pc3) 0.3%
C6 (pc6) 2.5%
C7 (pc7) 0.0%
C8 (pc8) 36.6%
C9 (pc9) 0.0%
C10 (pc10) 0.0%
If I quit Firefox then PC8 goes up to around 50%.
Full PowerTOP bits: https://gist.github.com/projectgus/e79923530392517c4e55064bb07b778d
(On the offchance anyone sees this and decides to buy an XPS 13 on this basis - it's still been a trip back to running Linux 10-15 years ago. I get random hard locks coming out of suspend, screen flickers when the laptop gets hot, glitchy touchpad driver, USB Type C is WIP, etc. Have spent way too much time compiling kernels and trawling forums. I wish I'd done my homework beforehand instead of thinking "well, Dell ships Linux on it from factory. How bad can it be?")