Getting PSR (Panel Self-Refresh) on T540p — electrical compatibility with T560 (or any other) display panels?

Message

intelfx · #1 Post by **intelfx** » Tue Jan 10, 2017 1:07 am

Hello,

it is well-known that in Intel platforms the deepest package C state to which transition is possible depends on screen resolution. In Haswell systems (T540p), having a WQHD (2880x1620) display panel effectively limits you to PC3 state and consequently 11W idle power consumption (in Linux). If I reduce my display resolution to 1024x768, power consumption instantly drops to 7-8W, yielding a significant saving. However, if PSR (Panel Self-Refresh) is active, then there are no limits on package C-state and power consumption then depends on actual frequency of changing the on-screen content (which is quite low in my case).

Obviously, panel self-refresh must be supported by both the chipset and the panel. As far as I know, PSR support in T-series panels appeared in T*60. Hence here is the question: is it possible to plug a display panel from T560(p) into a T540p laptop — i. e. are they electrically compatible? Or maybe there are other options of PSR-enabled compatible display panels?

#2 Post by **RealBlackStuff** » Tue Jan 10, 2017 7:21 am

Get the datasheets from a T540 and T560 or similar LCD and compare the LCD-connector pinouts.
If they are the same (and in the same position), you can swap screens.

intelfx · #3 Post by **intelfx** » Tue Jan 10, 2017 4:38 pm

RealBlackStuff wrote:Get the datasheets from a T540 and T560

Uh-huh. I'm having trouble finding part numbers for T560's panels and I have no clue which panels are "similar"; that's why I'm writing here in the first place.

Actually, if anybody who runs Linux on newer 15" ThinkPads here is reading this, then please tell me the output of

Code: Select all

# cat /sys/kernel/debug/dri/0/i915_edp_psr_status

along with your thinkpad model and (if possible) your display panel part number.

#4 Post by **Tasurinchi** » Fri Jan 13, 2017 8:55 am

intelfx wrote:I'm having trouble finding part numbers for T560's panels

Here is the one for the T560 (check page 4), and here the one for the T540/p (check page 8 )

intelfx · #5 Post by **intelfx** » Fri Jan 13, 2017 9:26 pm

Tasurinchi wrote:Here is the one for the T560 (check page 4), and here the one for the T540/p (check page 8 )

Thanks. That's a pity — same part number for WQHD panel... (i. e. no PSR on T560 in fact)

intelfx · #6 Post by **intelfx** » Fri Jan 13, 2017 9:28 pm

So, on to the plan B. Does anyone know of a 15" ThinkPad with WQHD display and PSR active?