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[Kernel][Stock1.3][Already included in CM7] Dalingrin's OC kernel [09/01/11]

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dirtmaster88
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Don't post often but just wanted to give a shout out to say many thanks for all your hard work. Got my first nook just the other day and am really amazed at what it's all capable of, especially with your kernel running. It really woke up the beast inside of it :)
 
dalingrin
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Quote:
Originally Posted by MedLine View Post
thanks for new kernel, 061811 OC kernel problem-free nearly 2 weeks, time to move on.

trying to undervolt cm7 on 063011 but think my nook not cooperating. at stock voltage my sr_adjust_vsel (pastebin here) somewhat resembles what searius posted few days ago, with opp1 - 3 already undervolted although not as generously as searius. if i use Nook Tweaks to reduce opp1 - 3 by 100mV each i think my nook just adjusts the voltage right back to nearly where it was, if i'm reading the sr_adjust_vsel numbers correctly (pastebin here), regardless of any concurrent underclocking.

other than that it's probably going to be problem free with 063011 kernel, like it's been for a long time now.
Well, I am not overriding SmartReflex. I believe this process also warrants explanation:

SmartReflex is TI's version of dynamic voltage control. Every Nook has values in read-only registers that seeds the voltage calibration algorithms. These algorithms will choose a voltage per stepping based upon your specific hardware. In essense, the voltage assigned in the kernel is a sort of suggestion. SmartReflex will then take that suggestion along with the values in the read-only registers and decided on a voltage that is stable. In other words, when you assign a voltage for a stepping, SmartReflex will decide on a voltage based upon your input. SmartReflex has a limited window around your suggested voltage to choose from, for example it might be +/- 0.5v from what you choose in Nook Color Tweaks.

SmartReflex has two main purposes:
- By calibrating the voltage based on your hardware, the Nook can change the voltage as your CPU ages. Resistance often increases with age and may require additional voltage to remain stable, say 5 years from now.
- SmartReflex also aims to use the least voltage possible. Your Nook may need less voltage than mine does to remain stable at 800mhz.

So, SmartReflex actually undervolts already, as I've said in the past. However, SmartReflex is often fairly conservative with undervolting, especially on the upper steppings like 3, 4 and 5.

This means undervolting on stepping 1 or 2 may not have much, if any impact, on the final voltage the Nook decides to run. In my experience, stepping 1 and 2 are already well undervolted already and decreasing the voltage only leads to a 0.03v change. This may or may not be true for your Nook though as each can run at different voltages.

I think voltage control has the most value in the 4th and 5th stepping. Perhaps you only want to overclock to 1.1ghz. In this case, I would make stepping 5 1.1ghz and then decrease the voltage on stepping 5. Here, the voltage control can make a significant impact. The same can be true if you want to increase the voltage on stepping 4 or 5.

Also note that I reset the calibrated voltage after you change the voltage in Nook Color Tweaks. If you inspect sr_adjust_vsel you will see that the right hand columns will be 0x0. The calibration will not take place until your Nook changes steppings. Once the Nook goes to the stepping with 0x0 you will see it populate with the calibrated voltage.
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actorman46
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So what are the advantages / disadvantages to playing around with the voltage? How does it effect overclocking? Just want to understand what I'm doing before I play around too much.

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Jotokun
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(Last edited by Jotokun; 1st July 2011 at 06:51 AM.)
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Originally Posted by actorman46 View Post
So what are the advantages / disadvantages to playing around with the voltage? How does it effect overclocking? Just want to understand what I'm doing before I play around too much.

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By increasing voltage, you can potentially achieve higher overclocks, but risk damaging your hardware. By lowering voltage, you can potentially achieve better battery life without sacrificing performance, but risk instability.

I've only been playing around with undervolting for a little bit, but so far it looks like on mine, the limit for stepping 5 at 1.2ghz is 1.25v (default is 1.375). Setting it to anything lower causes the entire tablet to lock up the instant I hit apply. For stability testing I've been letting an N64 emulator run for a few minutes since it stresses the device enough to go to the highest stepping, going down in voltage a bit and repeating.

Edit: Spoke too soon. 1.25v isnt stable at that speed.
Current phone - Nexus 4 16GB (CM10.1 RC2)
Current Tablet - Nexus 10 32GB (CM10.1 Nightly)
Previous devices - Motofail Backflip (CM7.2 Stable), Motofail Atrix 4G (CM10), HP Touchpad (CM9), Asus Transformer TF700 + dock (rooted stock ICS), Nook Color (CM7.1), Samsung Blackjack II (WinMo 6.1)
 
joenathane
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Great work Dalingrin!
 
actorman46
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(Last edited by actorman46; 1st July 2011 at 07:24 AM.)
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Quote:
Originally Posted by Jotokun View Post
By increasing voltage, you can potentially achieve higher overclocks, but risk damaging your hardware. By lowering voltage, you can potentially achieve better battery life without sacrificing performance, but risk instability.

I've only been playing around with undervolting for a little bit, but so far it looks like on mine, the limit for stepping 5 at 1.2ghz is 1.25v (default is 1.375). Setting it to anything lower causes the entire tablet to lock up the instant I hit apply. For stability testing I've been letting an N64 emulator run for a few minutes since it stresses the device enough to go to the highest stepping, going down in voltage a bit and repeating.

Edit: Spoke too soon. 1.25v isnt stable at that speed.
Thanks! Makes perfect sense. I've started playing with undervolting and it helps with my nook's over heating when overclocked. This is a great!

Running stepping 3 4 and 5 at 1.30 and overclocked to 1200. Nook much cooler.

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Jotokun
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I've currently got mine at

1 (300mhz) - 0.8125v
2 (600mhz) - 1.0v
3 (800mhz) - 1.1875v
4 (1100mhz) - 1.25v
5 (1200mhz) - 1.3v

Could probably do a little better than that, I know 5 can run at 1.25 for a bit but then it starts randomly shutting off on mine. Still, its pretty good, hope its stable in actual day-to-day use. Looking forward to seeing what this does to my battery life.
Current phone - Nexus 4 16GB (CM10.1 RC2)
Current Tablet - Nexus 10 32GB (CM10.1 Nightly)
Previous devices - Motofail Backflip (CM7.2 Stable), Motofail Atrix 4G (CM10), HP Touchpad (CM9), Asus Transformer TF700 + dock (rooted stock ICS), Nook Color (CM7.1), Samsung Blackjack II (WinMo 6.1)
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dalingrin
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Quote:
Originally Posted by Jotokun View Post
I've currently got mine at

1 (300mhz) - 0.8125v
2 (600mhz) - 1.0v
3 (800mhz) - 1.1875v
4 (1100mhz) - 1.25v
5 (1200mhz) - 1.3v

Could probably do a little better than that, I know 5 can run at 1.25 for a bit but then it starts randomly shutting off on mine. Still, its pretty good, hope its stable in actual day-to-day use. Looking forward to seeing what this does to my battery life.
I can't go all the way down to 1.25v @ 1.1ghz
 
runhopskipjump
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Quote:
Originally Posted by Jotokun View Post
I've currently got mine at

1 (300mhz) - 0.8125v
2 (600mhz) - 1.0v
3 (800mhz) - 1.1875v
4 (1100mhz) - 1.25v
5 (1200mhz) - 1.3v

Could probably do a little better than that, I know 5 can run at 1.25 for a bit but then it starts randomly shutting off on mine. Still, its pretty good, hope its stable in actual day-to-day use. Looking forward to seeing what this does to my battery life.
Using the same voltages and settings with no major issues so far. I played an avi file in moboplayer, used greader pro, watched a couple YouTube view and typed this message. I will report any issues I come across. I only notice a slight lag with thumb keyboard and while rotating the screen.

Nooking with Encore/Mecha via DasBAMF
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Instructions: How to flash boot.img via fastboot For Mac

 
dalingrin
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My settings for those who care:
300mhz @ 0.925v
600mhz @ 1.05v
800mhz @ 1.2v
1100mhz @ 1.275v
1200mhz @ 1.325v

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