mk808 over clock

[white-enochian]

Tried overclock apps but the frequence doesn't actual change

[userx]

Not possible at this time. Kernel is hard coded/locked down.
Kernel developer said over clocking the RK3066 chips could/will fry the circuit.
Might get 1.4 CPU over clock when Andrew unlocks the kernel but nothing more.

[white-enochian]

thats odd iv read alround about people running at 1.6 on there mk808s and how much faster tjhey perform ect they most believe the overclock apps then and dont actualy check with other apps what the cpu is actualy running at. thats a shame my cpu is normaly only around 800 something mhz

[AndrewDB]

Not a good idea

Hi,
The RK3066 supports a max. clock frequency of 1.6GHz, and so does the RK3066 kernel source code.
Unfortunately, the MK808 is particularly critical regarding heat dissipation (despite the heatsinks on both sides of the PCB) because it lacks a proper voltage controller to scale the core voltage when the frequency changes. In other words, it runs hot because the two Cortex-A9 cores always get the same voltage, which is the design voltage for 1.2GHz.
As far as I know the MK808 is the only RK3066 PC stick to suffer from this design limitation. ALL the other RK3066 PC sticks and tablets have a proper voltage controller implemented.
By unlocking the higher frequencies in the kernel you may be able to run MK808 above 1.2GHz i.e. up to 1.6GHz, but there are two problems:
1) Since the cores are not guaranteed to run at frequencies above 1.2GHz with the fixed voltage in the MK808, you may or may not experience random lockups.
2) Heat dissipation will increase. Since the RK3066 does not have a thermal protection circuit (as far as I know), it will happily burn itself out if you order it to (by running full speed without proper airflow to cool down the heatsinks).

Here is the relevant code in the kernel (as far as I know):
{.frequency = 504 * 1000, .cpu_volt = 1100 * 1000, .logic_volt = 1125 * 1000},//0.975V/1.000V
{.frequency = 816 * 1000, .cpu_volt = 1125 * 1000, .logic_volt = 1150 * 1000},//1.000V/1.025V
{.frequency = 1008 * 1000, .cpu_volt = 1125 * 1000, .logic_volt = 1150 * 1000},//1.025V/1.050V
{.frequency = 1200 * 1000, .cpu_volt = 1175 * 1000, .logic_volt = 1200 * 1000},//1.100V/1.050V
{.frequency = 1272 * 1000, .cpu_volt = 1225 * 1000, .logic_volt = 1200 * 1000},//1.150V/1.100V
{.frequency = 1416 * 1000, .cpu_volt = 1300 * 1000, .logic_volt = 1200 * 1000},//1.225V/1.100V
{.frequency = 1512 * 1000, .cpu_volt = 1350 * 1000, .logic_volt = 1250 * 1000},//1.300V/1.150V
{.frequency = 1608 * 1000, .cpu_volt = 1425 * 1000, .logic_volt = 1300 * 1000},//1.325V/1.175V

Edit: in the kernel there is a rather crude mechanism for switching to lower operating frequencies depending on the chip temperature. So I assume there is a core temperature sensor somewhere on the chip.

[Krinyo]

Hi,
The RK3066 supports a max. clock frequency of 1.6GHz, and so does the RK3066 kernel source code.
...

I think this explain why only max 1416 Mhz reachable with setcpu. I'm overclocking succesfully my MK808 to this clock speed with setting governor to performance. No issues at all, performance is great, heat is acceptable. What I really need is this 1416 Mhz clock speed with ondemand scaling... it is possible with custom kernel?

[AndrewDB]

I think this explain why only max 1416 Mhz reachable with setcpu. I'm overclocking succesfully my MK808 to this clock speed with setting governor to performance. No issues at all, performance is great, heat is acceptable. What I really need is this 1416 Mhz clock speed with ondemand scaling... it is possible with custom kernel?

The ondemand cpufreq governor is available in the kernel (actually all the other governors are available in the kernel and compile correctly), check in /sys whether you can enable it in your specific setup. However, imho for these ARM devices, the most effective governor is the "interactive" governor (immediately goes to highest frequency on high loads and slowly scales down to lower frequencies on lower loads).

BTW please substitute 1.416GHz instead of 1.2GHz in my post above concerning the MK808. 1.416GHz is the default max. frequency for the MK808 (they probably commented out the higher frequencies in the MK808 kernel).

[Spotopolis]

I use No-Frills CPU Control and can get 1.6GHz. Ive ran other apps and they are all reporting 1.6GHz. I havent had any problems with it. I run max 1.6 min 1.0 ondemand noop.

[Krinyo]

I use No-Frills CPU Control and can get 1.6GHz. Ive ran other apps and they are all reporting 1.6GHz. I havent had any problems with it. I run max 1.6 min 1.0 ondemand noop.

It's false reading, the MK808 not able to reach 1,6 Ghz, 1416 Mhz the max, and only with userspace or performance governor. No-Frills not changing anything, SetCPU is the only which able to overclock UG802 and MK808. Try with Linpack, the Mflops performance is show everything.

AndrewDB: ondemand and interactive governor only reach 1008/1200(?) MHz max if selected, regardless what I set in SetCPU as max speed. I think there is some misconfiguration in the kernel settings. All this with Finless latest stable ROMs.

PS: sorry about my bad english...

[AndrewDB]

...
AndrewDB: ondemand and interactive governor only reach 1008/1200(?) MHz max if selected, regardless what I set in SetCPU as max speed. I think there is some misconfiguration in the kernel settings. All this with Finless latest stable ROMs.

I have to spend some time to carefully examine the source code we have for this, but usually you can modify the max and min scaling frequencies for each governor, as root, by writing the appropriate values in /sys/devices/system/cpu/cpu0/cpufreq/<something> (check the correct path).

The Rockchip cpufreq source code itself is not well written imho, and there are very few comments. It's not easy for me to say at this stage where the max. clock frequency is defined.

[Spotopolis]

It's false reading, the MK808 not able to reach 1,6 Ghz, 1416 Mhz the max, and only with userspace or performance governor. No-Frills not changing anything, SetCPU is the only which able to overclock UG802 and MK808. Try with Linpack, the Mflops performance is show everything.

PS: sorry about my bad english...

Why is it that when I am running 1.6GHz Performance compared to 1.008GHz in benchmarking that I get a lot higher scores @1.6GHz if it is a false reading?

[Krinyo]

Why is it that when I am running 1.6GHz Performance compared to 1.008GHz in benchmarking that I get a lot higher scores @1.6GHz if it is a false reading?

Yes, false reading, MK808 maximum CPU freq is 1416 Mhz. Install SetCPU, and try it. You won't get higher performance than 1416 Mhz if you set higher, like 1,6 Ghz.

[Finless]

I have to spend some time to carefully examine the source code we have for this, but usually you can modify the max and min scaling frequencies for each governor, as root, by writing the appropriate values in /sys/devices/system/cpu/cpu0/cpufreq/<something> (check the correct path).

The Rockchip cpufreq source code itself is not well written imho, and there are very few comments. It's not easy for me to say at this stage where the max. clock frequency is defined.

Even if you do that the kernel still needs to enable it. 2Dark4U has now compiled kernels that allow higher clock adjustments, etc. Of course at the risk of brning your unit out!

Bob

[AndrewDB]

Even if you do that the kernel still needs to enable it. 2Dark4U has now compiled kernels that allow higher clock adjustments, etc. Of course at the risk of brning your unit out!

Bob

Yes, I wonder if the small gain in speed is worth the trouble. I find these RK3066 devices fast enough already!

[Krinyo]

Yes, I wonder if the small gain in speed is worth the trouble. I find these RK3066 devices fast enough already!

We will see under Ubuntu.

@ 1 GHz the multicore performance is 55-56 Mflops, while @ 1416 Mhz computing power pumped to 90-92 Mflops. If we do this properly with ondemand scaling then performance is great, and heat not a problem. MK808 cooler with heatsinks than UG802...

[planespotter]

Edit: in the kernel there is a rather crude mechanism for switching to lower operating frequencies depending on the chip temperature. So I assume there is a core temperature sensor somewhere on the chip.

It seems like over-temperature protection starts from 50 degrees!

#define TEMP_LIMIT_FREQ 816000


static const struct cpufreq_frequency_table temp_limits[] = {
{.frequency = 1416 * 1000, .index = 50},
{.frequency = 1200 * 1000, .index = 55},
{.frequency = 1008 * 1000, .index = 60},
{.frequency = 816 * 1000, .index = 75},
};

I use my mk809 II in an outdoor enclosure exposed to high temperatures during the day and I'm having issues with cpu throttling by "excessive" temperature.
I wonder is there any specific reason that the limit starts from 50C ? I think it's normal for the chip to run at 60-70C

Graphs attached speak for themselves.