[FAQ23368] 對最高頻做降頻-MT6853

[DESCRIPTION]

有些客戶需要降低最高頻，那麼修改gFreqTbl[].

[SOLUTION]

修改方法：

以6853平台為例，如果需要把最高頻4266降低到3200.

/vendor/mediatek/proprietary/bootable/bootloader/preloader/platform/mt6853/src/drivers/dramc_pi_main.c
  DRAM_DFS_FREQUENCY_TABLE_T gFreqTbl[DRAM_DFS_SRAM_MAX] =
 {
      {LP4_DDR3200 /*0*/, DIV8_MODE, SRAM_SHU1, DUTY_LAST_K,  VREF_CALI_OFF,  CLOSE_LOOP_MODE},  // highest freq of term group (3733) must k first.
      {LP4_DDR4266 /*1*/, DIV8_MODE, SRAM_SHU0, DUTY_NEED_K,  VREF_CALI_ON,   CLOSE_LOOP_MODE},  // highest freq of term group (3733) must k first.
......

 };      

需要修改最高頻SRAM_SHU0對應的freq_sel, 預設SRAM_SHU0對應的freq_sel為LP4_DDR4266(4266Mhz)。

如果要把最高頻4266降低到3200，需要把LP4_DDR4266改成LP4_DDR3200.

即：LP4_DDR4266 => LP4_3200

DRAM_DFS_FREQUENCY_TABLE_T gFreqTbl[DRAM_DFS_SRAM_MAX] = {
      {LP4_DDR3200 /*0*/, DIV8_MODE, SRAM_SHU1, DUTY_LAST_K,  VREF_CALI_OFF,  CLOSE_LOOP_MODE},  // highest freq of term group (3733) must k first.
      {LP4_DDR3200 /*1*/, DIV8_MODE, SRAM_SHU0, DUTY_NEED_K,  VREF_CALI_ON,   CLOSE_LOOP_MODE},  // highest freq of term group (3733) must k first.
......

}