全志R系列启动频率的修改方法？

本回答来源全志R系列启动频率的修改方法

方法一：进入系统后从寄存器更改。

１．利用sunxi_dump节点启动后更改为1.2G。（具体寄存器以具体IC为准）
　　　　

echo 0x01c20000 > /sys/class/sunxi_dump/dump;
　　　　cat /sys/class/sunxi_dump/dump;
　　　　echo 0x01c20000 0x90001810 > /sys/class/sunxi_dump/write;
　　　　cat /sys/class/sunxi_dump/write;

方法二：全部配置好后再启动。

１．内核配置选上dvfs驱动

make kernel_menuconfig
        CPU Power Management  --->
                    CPU Frequency scaling  --->
                             [*] CPU Frequency scaling   
  │ │                                      <*>   CPU frequency translation statistics      
  │ │                                      [ ]     CPU frequency translation statistics details  
  │ │                                            Default CPUFreq governor (performance)  --->        
  │ │                                      -*-   'performance' governor                           
  │ │                                      < >   'powersave' governor        
  │ │                                      < >   'userspace' governor for userspace frequency scaling
  │ │                                      < >   'ondemand' cpufreq policy governor      
  │ │                                      < >   'interactive' cpufreq policy governor           
  │ │                                      < >   'conservative' cpufreq governor              
  │ │                                            ARM CPU frequency scaling drivers  --->
                                                        [*] SUNXI CPUFreq driver support

利用调频策略的节点更改
echo usrspace > scaling_governor
echo 频点 > scaling_setspeed

２．sys_config.fex配置.

boot_clock=912
extremity_freq = 1200000000
max_freq = 1200000000
LV1_freq = 1200000000

方法三：系统无法启动时进入uboot临时更改使正常。
按住s启动进入uboot
执行：

sunxi#setcfg dvfs_table
–dvfs_table–
extremity_freq :912000000?1200000000
max_freq :1200000000?
min_freq :60000000?
LV_count :8?
LV1_freq :1200000000?
LV1_volt :1200?
LV2_freq :912000000?
LV2_volt :1100?
LV3_freq :912000000?
LV3_volt :1100?
LV4_freq :912000000?
LV4_volt :1100?sunxi#boot

需要更改的直接在后面输入更改的数字，不需要更改就按enter,最后按下ctrl+c停止设置回到
sunxi#命令行，输入boot重启即可。