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[KERNEL][G935] AMOLED PWM flicker free

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By Wootever, Senior Member on 12th December 2016, 11:40 AM
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19th December 2016, 09:06 PM |#11  
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Some information about the mentioned deterioration that increases on low brightness; it is called mura defects:
Quote:

Mura: The Japanese word for blemish has been widely adopted by the display industry to describe almost all irregular luminosity variation defects in liquid crystal displays.
Mura defects are caused by process flaws usually related to cell assembly, which affect the transmission of light through the display.
The cyclical nature, randomness, and often, low contrast of mura makes accurate detection and classification extremely difficult for LCD manufacturers.

In short: mura defects are small irregularities / deviations caused by the OLED production process.
Although this is a typical behaviour for AMOLED displays, the pwmfree kernel might increase the visibility of those mura defects due to the reduced pixel current on lower brightness.




The PWM effect is also used to mask those mura defects, so they become less visible:
Quote:

Another aspect [of the PWM mechanism] is to provide an organic light emitting display device and a driving method thereof by which a transverse and longitudinal mura defect or irregular luminosity variation defects of a panel due to process flaws, for example, caused by a lack of driving currents of the panel can be prevented.

Samsung patent description of the mura defects:
Quote:

However, although the smart dimming method according to the teachings of the present invention has the optical characteristics of a 300 cd/m2 luminance step, a mure defect may be generated by a deviation of a pixel current due to a low current for pixel driving at a low luminance/low grayscale, and a dispersion of the optical characteristics, such as color difference (MPCD: Minimum Perceptual Color Difference), color temperature, and grayscale linearity, may increase. Due to the problem associated with the increased dispersion of the optical characteristics at a low luminance, a expressible minimum luminance should be limited to 40 cd/m2. If the minimum luminance set to lower than 40 cd/m2, the optical characteristics deteriorates.

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26th December 2016, 12:16 AM |#12  
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Kernel notes V9:
  • Added compatibility for encrypted devices
  • Reduced minimal brightness to 7 candela
Download pwmfree Kernel for G935

Note: If your device is encrypted, Secure startup needs to be disabled!
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26th December 2016, 02:55 AM |#13  
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flash version 9 phone wont boot....

EDIT: nvm everything works...
27th December 2016, 01:34 AM |#14  
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THANKS non root stock tar. file odın flash work ?
28th December 2016, 10:09 PM |#15  
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Both files (Odin TAR and Recovery ZIP) are identical and includes SuperSU root. They are just using a different flashing process.

Edit:
Attached Odin3 flashing tool.
Attached Files
File Type: zip Odin3 v3.12.3.zip - [Click for QR Code] (1.10 MB, 48 views)
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30th December 2016, 12:22 AM |#16  
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hi, is it me or the wirless charging is slower than other kernel? thanks
2nd January 2017, 03:30 PM |#17  
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nice work mate :)
bro please make the kernel compatible with note7 port rom . i'm on hydra rom note7 rom for s7 edge.
kee u the great work
2nd January 2017, 06:57 PM |#18  
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I searched for some information if the modified PWM mechanism might (negatively) impact OLED lifetime.
But interestingly enough it seems that the pwm free approach might even increase it's lifetime:

The adjustment of the nominal current must be realized by the DC amplitude of the driver (see above). Nevertheless, dimming of OLEDs is allowed also by pulse width modulation (PWM).
  • Reduction of the DC amplitude for dimming will increase the OLED lifetime disproportionally (figure 7), but may lead to color shifts at white OLEDs.
  • Reduction of the mean current by pulse width modulation (PWM) will increase the OLED lifetime not that much (only proportionally, figure 7) but keeps the color point of white OLEDs stable.



Summary:
  • 150% OLED lifetime without PWM and more visible mura defects.
  • 100% OLED lifetime with PWM and less visible mura defects.
  • Color shifts are less noticeable due to better AMOLED panel quality and color correction mechanisms.

Source: Dimming of OLEDs - OSRAM
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4th January 2017, 01:09 PM |#19  
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Hi Wootever,

first let me thank you for your great work.

I've purchased S7 Edge today just to try PWMFree kernel (I wasn't able to use SAMOLED phones since Galaxy S3 / Note 3 onwards), but have to report that after flashing it (latest version 11) the phone is stuck on logo (Galaxy S7 Edge powered by Android).

Flashed with Odin, seemed to go through ok:

<ID:0/008> Added!!
<ID:0/008> Odin engine v(ID:3.1203)..
<ID:0/008> File analysis..
<ID:0/008> SetupConnection..
<ID:0/008> Initialzation..
<ID:0/008> Get PIT for mapping..
<ID:0/008> Firmware update start..
<ID:0/008> SingleDownload.
<ID:0/008> boot.img
<ID:0/008> RQT_CLOSE !!
<ID:0/008> RES OK !!
<ID:0/008> Remain Port .... 0
<OSM> All threads completed. (succeed 1 / failed 0)
<ID:0/008> Removed!!

The phone was running latest official version that was installed though OTA (G935FXXU1BPLB).

Any hints appreciated

UPDATE: did factory reset / wipe data from bootloader menu twice and the phone boots
Will try to use the phone now and see how it goes.
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4th January 2017, 03:38 PM |#20  
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Okay, I'm very happy to report that your PWMfree kernel does the magic!

Will have to use the phone for a few more days in order to make a final judgement whether that remaining 60Hz flicker makes any discomfort or not, but I can already confirm that with your kernel I can again use newer Samsung devices - the difference is night and day =)

Is there a way for you to make a test kernel even without 60Hz flicker for comparison?

And how/where can I donate?
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4th January 2017, 04:06 PM |#21  
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Any plan for a Nougat (ZPLN) version? (or maybe it is already compatible?) I would really like to give that kernel a try
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