From: http://padhz.com/bbs/forum.php? MoD = viewthread & tid = 688.
The main talk about rk3066 and AML8726-MX
Frequency and power consumption/performance/solution cost
1. frequency and power consumption
Dvfs of 1.1 rk30 (dynamic voltage frequency adjustment)
Rk3066 features a maximum frequency of 1.6 GHz and a minimum of 252 MHz. Among them to ARM core power supply is wm8326g DC-DC buck2. I observed the results are as follows:
Rk3066 A9 clock (MHz)/voltage (V)
252 1.050
504 1.050
816 1.075
1008 1.075
1200 1.175
1272 1.225
1416 1.300
1512 1.350
1608 1.350
The first column is the clock speed, and the second column is the voltage. It can be seen that the voltage is relatively low when the frequency is low, while the voltage is as high as 1.35 V at the high frequency of G, and the limit is reached. It can be said that the potential of rk3066 has been fully realized.
We can properly compare other dual cores, such as Samsung exynos 4210
Exynos 4210 A9 clock (MHz)/voltage (V)
200 0.975
500 1.000
800 1.100
1000 1.200
1400 1.275
It can be found that the dvfs settings of rk3066 are relatively reasonable and complete.
In addition, we can simply think that the power consumption at full load is directly proportional to the frequency and the square of the voltage.
At present, the mass production of AML8726-MX firmware for 1.2GHz@1.2V, early testing firmware for 1.32GHz@1.2V. AML also has multiple frequency levels, but I cannot detect the voltage changes at the same time. From the perspective of a single chip, the AML can also increase the clock speed by adding voltage later. But the premise is to have relatively complete dvfs.
In general, rk is relatively well-developed in terms of frequency and voltage control. To some extent, this also makes the rk3066 scheme currently have good temperature control performance (of course, the 9.7-inch large machine and large heat sink are also helpful)
1.2 kernel Governor Settings
The governor in the kernel is mainly used to determine the system load and adjust the CPU frequency.
The following are common Governor:
Reference: http://forum.xda-developers.com/showthread.php? T = 1369817
1. OnDemand
When there is a load, the frequency immediately increases to the maximum value set by the user. If you find that the CPU usage is relatively low, the frequency drops step by step until a reasonable value.
If the user runs another program, the frequency will immediately increase to the maximum value, and then return step by step.
The OnDemand adjustment time is when the work queue is switched, so once a task is completed, the system tries to minimize the frequency. At this time, if you initiate another task, the system will immediately jump to the maximum value. As a result, the CPU frequency is easy to jump back and forth between the maximum and minimum values during multi-task operations, which is not conducive to energy saving.
OnDemand is the most common governor in smart devices. Because it is more active and frequently used, the experience is smoother. Although it will consume more power ......
The Samsung devices at hand are basically OnDemand.
2. Performance and powersave
Performance is to set the frequency to the maximum value, which is generally used for splitting.
Powersave, on the contrary, sets the frequency to the minimum value.
3. Conservative
This manager is more focused on maintaining at the lowest frequency. The system can increase the clock speed only when heavy and continuous loads are applied to the CPU. Therefore, the result is not smooth to use. Kaka's ...... Especially when the minimum frequency is low. It saves power.
4. Interactive
Similar to OnDemand, but the response is faster. Adjust the Frequency Based on the CPU load.
Unlike OnDemand, OnDemand performs frequency modulation during work queue switching, while interactive performs frequency modulation by specifying a time interval. Therefore, after a user executes a high-load application, as long as the time period is not over, the CPU will continue to be at the highest frequency. At this time, you can execute another program to get better performance, instead of repeating back and forth between the lowest frequency and the lowest frequency as OnDemand. Therefore, interactive is more suitable for multi-task environments, faster response. Of course, the disadvantage is that it takes longer to stay at a high frequency and consumes less power than OnDemand.
By default, the Samsung machine and Huawei mediapad (Qualcomm solution) at hand are OnDemand.
On the aml mx machine, the firmware of the beta version that was previously refreshed is OnDemand by default, which is quite smooth. However, many of my friends reported that jieshang had a hard time understanding it at the beginning. Later I brushed the 0508 production firmware on the official website and found that it was a big pitfall: the default is conservative, in addition, only performance (the High-Performance Mode in the corresponding settings) and conservative (the normal mode in the corresponding settings) are implemented, while OnDemand is not optional and is not implemented.
Therefore, in the default conseravative manager, the system can easily reduce the frequency to 96 MHz. At this time, the UI will be slide and it will not be smooth. It is smooth to set to performance, but it is always high. Therefore, we still hope to provide a firmware similar to the firmware version that supports the OnDemand manager. (The new firmware on the 0514 official website seems OK)
The omap4 model and rk3066 of the smart machine use interactive manager. In the smart device settings, high_speed is the highest clock speed of the machine: omap4430 is 1 GHz, and the 4460 model is 1.5 GHz. What makes the rk solution a coincidence is that they set high_speed to 816 MHz instead of the maximum clock speed of the machine at 1.6 GHz. In this way, even under load, the machine will be at 816 MHz most of the time, rather than the highest 1.6 GHz. It saves power consumption, controls fever, and delivers a good user experience. Rk has made some effort to improve it.
In addition, other logic and Mali-400 on the rk3066 chip are also configured with dynamic voltage adjustment, which has three levels: 1.125 V/1.200 V/1.250v.
2. Solution cost
2.1 Power Supply
Rk3066 is still working hard on power supply this time. It uses ousheng's wm8326g as the power management chip.
Allwinner A10: axp209 2dc-dc (1.6a + 1.2a) + 5ldc
Rk2918: act8891 3dc-dc (2 * 1.15a + 1.3a) + 4ldos
AML8726-MX: DC-DC buck ?? A + axp202 2dc-dc (1.6a + 1.2a) + 5ldos
Rk3066: wm8326g 4dc-dc (2 * 2.5a + 2 * 1.0a) + 10ldos
Tegra 2: tps658621 3dc-dc (2 * 1.5a + 2.0a) + 11ldc
Omap4: twl6030 7dc-dc (2 * 1.5a + 5 * 0.8a) + 11hba
Exynos 4210: max8997 7dc-dc + 21drop/act8847 4dc (2 * 2.8a + 2 * 1.5a) + 9drop
We can see that in order to feed 400 GHz A9 dual core and Mali-MP4 GPU, the use of wm8326g two 2.5a high current DC-DC Buck, respectively to arm A9 and GPU, to meet the peak power of high load.
I personally feel that such a PMU is still the key cost ...... I wonder if it will be changed to a cheaper Chinese model later.
2.2 others
The integration of rk3066 has improved compared with rk29, but it is a pity that LVDS is not integrated. In the past, the rk29 solution was used with a third-party LVDS chip to implement high-split screen drive. This rk3066 solution was used with rk's own rk610 LVDS chip. At the same time,