* 0 = OPP available.

                         */

                        max_freq = (~val & MAX_FREQ_MASK);

-

+ max_freq=~0x1FAF&MAX_FREQ_MASK

+            printk("max_freq=%x\n",max_freq);

+            max_freq=max_freq|OPP_NITRO_600MHZ_BIT;

                        if (max_freq & OPP_50_300MHZ_BIT)

                                am33xx_es2_1_opp_list[OPP_50_300_INDEX].

                                        default_available = true;

寄存器的值可以参考cpu手册的描述，如下

注意写入的是一个取反值与上Mask，即写入600M，max_freq=~0x1FAF&MAX_FREQ_MASK

文件系统的修改：

查看cpu频率

cat /sys/devices/system/cpu/cpu0/cpufreq/cpuinfo_cur_freq

设置cpu频率

echo 600000 > /sys/devices/system/cpu/cpu0/cpufreq/scaling_setspeed