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

T430/T440 and T530/540 series specific matters only
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intelfx
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Getting PSR (Panel Self-Refresh) on T540p ­— electrical compatibility with T560 (or any other) display panels?

#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?

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

#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.

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

#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 )
IBM Convertible 5140/L40SX/220/240/240X/2*340CSE/360PE/365XD/380D/380E/380XD/380Z/390/560E/560X/2*570/2*600/600E/750Cs/755C/760CD/760EL/760XD/770E
A20p/A22p/A31/i1600/G40/R50p/R61i/S30/SL510/2*T22/4*T4x/11*T6x/6*T40x/6*T5x0/3*W5x0/W700/3*X2x/4*X3x/3*X4x/5*X6x/3*X6xT/12*X2xx/4*X30x/Z60m/3*Z61x

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

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

#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?

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