Hi Daniel, On 03.05.2016 00:47, Daniel Kulesz via coreboot wrote: > Hi all, > > On Mon, 2 May 2016 13:16:15 +0200 > Nico Huber <[email protected]> wrote: >> Regarding C3/C4 support, AFAIK, we implemented it fully but it just >> didn't work on the system we originally ported coreboot for (Roda/RK9). >> The system kept resetting whenever it should enter (or maybe exit) C3, >> IIRC. You could give it a try on your X200 though. Whatever the issue >> on the RK9 was, it might be board specific. >> >> If you want to try it, in src/mainboard/lenovo/x200/cstates.c add: >> { >> /* acpi C3 / cpu C3 */ >> 3, 0x02, 300, >> { ACPI_ADDRESS_SPACE_FIXED, 1, 2, { 1 }, 0x20, 0 } >> }, >> for C3 or >> { >> /* acpi C3 / cpu C4 */ >> 3, 0x02, 300, >> { ACPI_ADDRESS_SPACE_FIXED, 1, 2, { 1 }, 0x30, 0 } >> }, >> for C4. You can not have all of them, as ACPI only supports three >> C-states. > > Indeed this was a *VERY GOOD* hint! I added the line with the C4 > states and idle power consumption dropped to about 11.5W running my > regular OS and with Wifi on. So I again disassembled the > keyboard/palmrest, removed the wifi card and did exactly the same > measurements as before. And here are the results: > > Benchmark results: almost like before (not crappy like with vendor > BIOS!), a little worse because it probably takes a few ms for the CPU > to wake up from C4 first. Stress test: >37.2W (as before) > > Idle, max brightness: 10.8W (!!) > Idle, lowest brightness: 7.8W (!!) > > ...and after running "powertop --auto-tune": > Idle, max brightness: 9.9W > Idle, lowest brightness: 6.9W > Screen off:6.4W > Very NICE!
> Sounds stupid, but I'm really impressed now! But... is there a reason > C4 is not enabled by default then? I mean, if it makes trouble, you > can always disable it (at least on Linux) with the command line > parameters as discussed previously. Imho, it should be at least > configurable using the regular config mechanism. > I guess, just nobody tried it before on a ThinkPad. The entries for C1/C2 are most probably copy-pasted from Roda/RK9. Thanks for testing this through! If you don't want to go further (https://coreboot.org/Git) somebody else will likely write a patch ;) Nico -- coreboot mailing list: [email protected] https://www.coreboot.org/mailman/listinfo/coreboot
